ORCID Profile
0000-0001-8588-1123
Current Organisation
The University of Edinburgh
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Publisher: No publisher found
Publisher: No publisher found
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 31-07-2008
DOI: 10.1057/JIBS.2008.50
Publisher: No publisher found
Publisher: No publisher found
Publisher: No publisher found
DOI: 10.1002/ECY.2482}
Publisher: Public Library of Science (PLoS)
Date: 10-11-2015
Publisher: No publisher found
Publisher: University of Chicago Press
Date: 04-2012
DOI: 10.1086/664686
Abstract: Trade-offs among life-history traits are central to evolutionary theory. In quantitative genetic terms, trade-offs may be manifested as negative genetic covariances relative to the direction of selection on phenotypic traits. Although the expression and selection of ecologically important phenotypic variation are fundamentally multivariate phenomena, the in situ quantification of genetic covariances is challenging. Even for life-history traits, where well-developed theory exists with which to relate phenotypic variation to fitness variation, little evidence exists from in situ studies that negative genetic covariances are an important aspect of the genetic architecture of life-history traits. In fact, the majority of reported estimates of genetic covariances among life-history traits are positive. Here we apply theory of the genetics and selection of life histories in organisms with complex life cycles to provide a framework for quantifying the contribution of multivariate genetically based relationships among traits to evolutionary constraint. We use a Bayesian framework to link pedigree-based inference of the genetic basis of variation in life-history traits to evolutionary demography theory regarding how life histories are selected. Our results suggest that genetic covariances may be acting to constrain the evolution of female life-history traits in a wild population of red deer Cervus elaphus: genetic covariances are estimated to reduce the rate of adaptation by about 40%, relative to predicted evolutionary change in the absence of genetic covariances. Furthermore, multivariate phenotypic (rather than genetic) relationships among female life-history traits do not reveal this constraint.
Publisher: American Psychological Association (APA)
Date: 10-2020
DOI: 10.1037/APL0000486
Abstract: The idea that in idual creativity derives from the interaction of personal traits and the situation in which the in idual operates, is one of the most prominent themes within the creativity literature. A review of the literature highlights 5 distinct interaction patterns observed in person-in-situation creativity research (trait activation, trait inhibition, trait substitution, trait channeling, and curvilinear interactions). Yet at present there is no integrative theory that can predict and explain all 5 interaction patterns. To develop such integrative theory, we propose the motivational lens model of person-in-situation creativity. The motivational lens model offers an integrative theoretical account of person-in-situation interactions through a parsimonious set of considerations: (a) whether the trait of interest is associated with intrinsic motivation for (activities conducive to) creativity or with extrinsic motivation (i.e., which can be directed toward creativity in response to extrinsic cues), (b) the extent to which the situation variable of interest reflects opportunities for creativity or expectations for creativity, and (c) whether the situation variable is linearly or curvilinearly related to opportunities or expectations. We discuss how the motivational lens model informs future creativity research and potentially person-in-situation research beyond the creativity domain. (PsycInfo Database Record (c) 2020 APA, all rights reserved).
Publisher: Oxford University Press (OUP)
Date: 04-2009
DOI: 10.1534/GENETICS.108.086801
Abstract: This work demonstrates that environmental conditions experienced by in iduals can shape their development and affect the stability of genetic associations. The implication of this observation is that the environmental response may influence the evolution of traits in the wild. Here, we examined how the genetic architecture of a suite of sexually dimorphic traits changed as a function of environmental conditions in an unmanaged population of Soay sheep (Ovis aries) on the island of Hirta, St. Kilda, northwest Scotland. We examined the stability of phenotypic, genetic, and environmental (residual) covariance in males during the first year of life between horn length, body weight, and parasite load in environments of different quality. We then examined the same covariance structures across environments within and between the adult sexes. We found significant genotype-by-environment interactions for lamb male body weight and parasite load, leading to a change in the genetic correlation among environments. Horn length was genetically correlated with body weight in males but not females and the genetic correlation among traits within and between the sexes was dependent upon the environmental conditions experienced during adulthood. Genetic correlations were smaller in more favorable environmental conditions, suggesting that in good environments, loci are expressed that have sex-specific effects. The reduction in genetic correlation between the sexes may allow independent evolutionary trajectories for each sex. This study demonstrates that the genetic architecture of traits is not stable under temporally varying environments and highlights the fact that evolutionary processes may depend largely upon ecological conditions.
Publisher: No publisher found
Publisher: Wiley
Date: 15-09-2019
DOI: 10.1111/JEB.13521
Abstract: Warming global temperatures are affecting a range of aspects of wild populations, but the exact mechanisms driving associations between temperature and phenotypic traits may be difficult to identify. Here, we use a 36-year data set on a wild population of red deer to investigate the causes of associations between temperature and two important components of female reproduction: timing of breeding and offspring size. By separating within- versus between-in idual associations with temperature for each trait, we show that within-in idual phenotypic plasticity (changes within a female's lifetime) was entirely sufficient to generate the observed population-level association with temperature at key times of year. However, despite apparently adequate statistical power, we found no evidence of any variation between females in their responses (i.e. no "IxE" interactions). Our results suggest that female deer show plasticity in reproductive traits in response to temperatures in the year leading up to calving and that this response is consistent across in iduals, implying no potential for either selection or heritability of plasticity. We estimate that the plastic response to rising temperatures explained 24% of the observed advance in mean calving date over the study period. We highlight the need for comparable analyses of other systems to determine the contribution of within-in idual plasticity to population-level responses to climate change.
Publisher: Wiley
Date: 10-04-2012
DOI: 10.1111/J.1558-5646.2012.01632.X
Abstract: Adaptive evolution occurs when fitness covaries with genetic merit for a trait (or traits). The breeder's equation (BE), in both its univariate and multivariate forms, allows us to predict this process by combining estimates of selection on phenotype with estimates of genetic (co)variation. However, predictions are only valid if all factors causal for trait-fitness covariance are measured. Although this requirement will rarely (if ever) be met in practice, it can be avoided by applying Robertson's secondary theorem of selection (STS). The STS predicts evolution by directly estimating the genetic basis of trait-fitness covariation without any explicit model of selection. Here we apply the BE and STS to four morphological traits measured in Soay sheep (Ovis aries) from St. Kilda. Despite apparently positive selection on heritable size traits, sheep are not getting larger. However, although the BE predicts increasing size, the STS does not, which is a discrepancy that suggests unmeasured factors are upwardly biasing our estimates of selection on phenotype. We suggest this is likely to be a general issue, and that wider application of the STS could offer at least a partial resolution to the common discrepancy between naive expectations and observed trait dynamics in natural populations.
Publisher: No publisher found
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Publisher: The Royal Society
Date: 24-07-2019
Abstract: Reductions in animal body size over recent decades are often interpreted as an adaptive evolutionary response to climate warming. However, for reductions in size to reflect adaptive evolution, directional selection on body size within populations must have become negative, or where already negative, to have become more so, as temperatures increased. To test this hypothesis, we performed traditional and phylogenetic meta-analyses of the association between annual estimates of directional selection on body size from wild populations and annual mean temperatures from 39 longitudinal studies. We found no evidence that warmer environments were associated with selection for smaller size. Instead, selection consistently favoured larger in iduals, and was invariant to temperature. These patterns were similar in ectotherms and endotherms. An analysis using year rather than temperature revealed similar patterns, suggesting no evidence that selection has changed over time, and also indicating that the lack of association with annual temperature was not an artefact of choosing an erroneous time window for aggregating the temperature data. Although phenotypic trends in size will be driven by a combination of genetic and environmental factors, our results suggest little evidence for a necessary ingredient—negative directional selection—for declines in body size to be considered an adaptive evolutionary response to changing selection pressures.
Publisher: Wiley
Date: 26-07-2018
DOI: 10.1111/EVO.13554
Abstract: Natural selection operates via fitness components like mating success, fecundity, and longevity, which can be understood as intermediaries in the causal process linking traits to fitness. In particular, sexual selection occurs when traits influence mating or fertilization success, which, in turn, influences fitness. We show how to quantify both these steps in a single path analysis, leading to better estimates of the strength of sexual selection. Our model controls for confounding variables, such as body size or condition, when estimating the relationship between mating and reproductive success. Correspondingly, we define the Bateman gradient and the Jones index using partial rather than simple regressions, which better captures how they are commonly interpreted. The model can be applied both to purely phenotypic data and to quantitative genetic parameters estimated using information on relatedness. The phenotypic approach breaks down selection differentials into a sexually selected and a "remainder" component. The quantitative genetic approach decomposes the estimated evolutionary response to selection analogously. We apply our method to analyze sexual selection in male dusky pipefish, Syngnathus floridae, and in two simulated datasets. We highlight conceptual and statistical limitations of previous path-based approaches, which can lead to substantial misestimation of sexual selection.
Publisher: Public Library of Science (PLoS)
Date: 28-01-2014
Publisher: Wiley
Date: 09-09-2010
DOI: 10.1111/J.1420-9101.2010.02084.X
Abstract: The breeder's equation, which predicts evolutionary change when a phenotypic covariance exists between a heritable trait and fitness, has provided a key conceptual framework for studies of adaptive microevolution in nature. However, its application requires strong assumptions to be made about the causation of fitness variation. In its univariate form, the breeder's equation assumes that the trait of interest is not correlated with other traits having causal effects on fitness. In its multivariate form, the validity of predicted change rests on the assumption that all such correlated traits have been measured and incorporated into the analysis. Here, we (i) highlight why these assumptions are likely to be seriously violated in studies of natural, rather than artificial, selection and (ii) advocate wider use of the Robertson-Price identity as a more robust, and less assumption-laden, alternative to the breeder's equation for applications in evolutionary ecology.
Publisher: University of Chicago Press
Date: 02-2008
DOI: 10.1086/524957
Abstract: Evolutionary theories of senescence predict that rates of decline in performance parameters should be shaped by early-life trade-offs between reproduction and somatic maintenance. Here we investigate factors influencing the rate of reproductive senescence in a long-lived seabird, the common guillemot Uria aalge, using data collected over a 23-year period. In the last 3 years of life, in idual guillemots had significantly reduced breeding success and were less likely to hold a site or attempt to breed. Females senesced at a significantly faster rate than males. At the in idual level, high levels of reproductive output earlier in life were associated with increased senescence later in life. This trade-off between early- and late-life reproduction was evident independent of the fact that as birds age, they breed later in the season. The rate of senescence was additionally dependent on environmental conditions experienced earlier in life, with evidence that harsh conditions lified later declines in breeding success. Overall, in iduals with intermediate levels of early-life productivity lived longer. These results provide support for the antagonistic-pleiotropy and disposable-soma theories of senescence and demonstrate for the first time in a wild bird population that increased rates of senescence in reproductive performance are associated with varying costs of reproduction early in life.
Publisher: No publisher found
Publisher: Wiley
Date: 2008
Publisher: No publisher found
DOI: 10.1111/NPH.15656}
Publisher: Elsevier BV
Date: 04-2018
Publisher: Informa UK Limited
Date: 05-2009
Publisher: The Royal Society
Date: 11-2014
Abstract: Testosterone is an important hormone that has been shown to have sex-specific links to fitness in numerous species. Although testosterone concentrations vary substantially between in iduals in a population, little is known about its heritable genetic basis or between-sex genetic correlations that determine its evolutionary potential. We found circulating neonatal testosterone levels to be both heritable (0.160 ± 0.064 s.e.) and correlated between the sexes (0.942 ± 0.648 s.e.) in wild red deer calves ( Cervus elaphus ). This may have important evolutionary implications if, as in adults, the sexes have ergent optima for circulating testosterone levels.
Publisher: Wiley
Date: 03-2009
DOI: 10.1111/J.1365-2656.2008.01489.X
Abstract: 1. Given energetic constraints, female reproductive strategy is expected to be shaped by a trade-off between offspring size and offspring number, the optimal resolution of which may vary with environmental conditions. 2. We tested the hypothesis that selection will favour the production of larger litters, even at some expense to offspring size, under good conditions (and vice versa in harsh environments) using data from a long-term study of an unmanaged population of Soay sheep on the islands of St Kilda, NW Scotland. 3. Both litter size (which is either 1 or 2) and offspring birth weight are under positive selection through female annual fitness, but the strength of selection varies systematically with environmental conditions. Age effects were also detected, with selection weakening as female age increases. 4. Consistent with theoretical predictions, the selective trade-off between litter and offspring size is shifted in favour of the latter under poor environmental conditions. Thus, direct selection on offspring birth weight increases under harsh environmental conditions, particularly for females producing twins. 5. However, singletons are only favoured when environmental conditions are very poor, and offspring weight is constrained to be low. Thus, the current low incidence of twinning (13.5% of litters produced since 1985) appears to be suboptimal with respect to the empirically estimated selection regime. Thus, litter size, a trait known to be heritable, may be expected to evolve upwards in this population. 6. Our study highlights the necessity of incorporating environmental heterogeneity and age structure into analyses of natural selection, and suggests that the common assumption of optimality used in models of life history may sometimes be problematic.
Publisher: Springer Science and Business Media LLC
Date: 12-2002
Publisher: Springer Science and Business Media LLC
Date: 22-05-2018
Publisher: Wiley
Date: 10-03-2009
DOI: 10.1002/JOB.600
Publisher: Springer Science and Business Media LLC
Date: 07-2001
DOI: 10.1038/35083580
Publisher: No publisher found
Publisher: Oxford University Press (OUP)
Date: 22-08-2016
Publisher: Wiley
Date: 10-2005
Publisher: University of Chicago Press
Date: 09-2009
DOI: 10.1086/603615
Abstract: In polygynous species, adult mortality is generally higher in males than in females, and theory predicts that this should result in the evolution of faster rates of senescence in males. Detailed investigations of sex differences in patterns of aging across the many and varied phenotypic characteristics associated with successful reproduction in wild populations of polygynous vertebrates are currently lacking. Here, we use longitudinal data collected from a wild red deer population to compare aging patterns across a range of life-history, behavioral, and morphological traits in both sexes. While males showed more rapid age-related declines in annual breeding success than did females, there was evidence of variation in aging rates among traits within each sex. Traits associated with male breeding performance showed a rapid decline in old age, whereas the morphology and phenology of antlers, a key male secondary sexual characteristic, showed minimal senescence. Female reproductive traits associated with regulation of estrus and gestation showed delayed senescence relative to traits associated with investment in offspring growth during gestation and lactation. Our results suggest that either natural selection or physiological constraint has caused an uncoupling of senescence rates in different physiological systems and, thus, different reproductive traits in this wild vertebrate population.
Publisher: No publisher found
Publisher: Wiley
Date: 05-06-2011
Publisher: No publisher found
Publisher: No publisher found
DOI: 10.1111/GCB.12926}
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Publisher: No publisher found
Publisher: Public Library of Science (PLoS)
Date: 13-06-2006
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Publisher: The Royal Society
Date: 23-01-2008
Abstract: Studies of populations in the wild can provide unique insights into the forces driving evolutionary dynamics. This themed issue of Proc. R. Soc. B focuses on new developments in long-term analyses of animal populations where pedigree information has been collected. These address fundamental questions in evolutionary biology concerning the genetic basis of phenotypic ersity, patterns of natural and sexual selection, the occurrence of inbreeding and inbreeding depression, and speciation. Contributions include the analysis of evolutionary responses to climate change, exploration of the genetic basis of senescence, the exploitation of advances in molecular genetic technology, and reviews of developments in quantitative genetic methodology. We discuss here common themes, specific problems and pointers for future research.
Publisher: Springer Science and Business Media LLC
Date: 18-05-2010
DOI: 10.1007/S00442-010-1656-7
Abstract: There has been growing interest in the determinants of the annual timing of biological phenomena, or phenology, in wild populations, but research on vertebrate taxa has primarily focused on the phenology of reproduction. We present here analyses of the phenology of the annual growth of a secondary sexual characteristic, antlers in red deer (Cervus elaphus) males. The long-term in idual-based data from a wild population of red deer on the Isle of Rum, Scotland allow us to consider ecological factors influencing variation in the phenology of growth of antlers, and the implications of variation in antler growth phenology with respect to the phenotype of antler grown (antler mass) and annual breeding success. The phenology of antler growth was influenced by local environmental conditions: higher population density delayed both the start date (during spring) and the relative end date (in late summer) of antler growth, and warmer temperatures in the September and April prior to growth advanced start and end dates, respectively. Furthermore, there was variation between in iduals in this phenotypic plasticity of start date, although not in that of end date of growth. The phenology of antler growth impacted on the morphology of antlers grown, with in iduals who started and ended growth earliest having the heaviest antlers. The timing of antler growth phenology was associated with breeding success in the following mating season, independently of the mass of antlers grown: an earlier start of antler growth was associated with siring a higher number of the calves born the following spring. Our results suggest that the phenology of traits that are not directly correlated with offspring survival may also regularly show correlations with fitness.
Publisher: No publisher found
Publisher: Elsevier BV
Date: 07-2014
Publisher: Wiley
Date: 12-04-2012
Publisher: Academy of Management
Date: 04-2021
Publisher: No publisher found
Publisher: Public Library of Science (PLoS)
Date: 02-2011
Publisher: No publisher found
Publisher: No publisher found
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Publisher: No publisher found
Publisher: University of Chicago Press
Date: 11-2004
DOI: 10.1086/424764
Abstract: Heritable phenotypic traits under significant and consistent directional selection often fail to show the expected evolutionary response. A potential explanation for this contradiction is that because environmental conditions change constantly, environmental change can mask an evolutionary response to selection. We combined an "animal model" analysis with 36 years of data from a long-term study of great tits (Parus major) to explore selection on and evolution of a morphological trait: body mass at fledging. We found significant heritability of this trait, but despite consistent positive directional selection on both the phenotypic and the additive genetic component of body mass, the population mean phenotypic value declined rather than increased over time. However, the mean breeding value for body mass at fledging increased over time, presumably in response to selection. We show that the ergence between the response to selection observed at the levels of genotype and phenotype can be explained by a change in environmental conditions over time, that is, related both to increased spring temperature before breeding and elevated population density. Our results support the suggestion that measuring phenotypes may not always give a reliable impression of evolutionary trajectories and that understanding patterns of phenotypic evolution in nature requires an understanding of how the environment has itself changed.
Publisher: Wiley
Date: 2003
DOI: 10.1046/J.1420-9101.2003.00503.X
Abstract: It has been suggested that fluctuating asymmetry (FA) in secondary sexual traits may be a useful indicator of either in idual quality or environmental stress. We tested this concept using a series of analyses of FA in male antler size in a wild red deer (Cervus elaphus) population, using four measures of size repeated across successive years on the same in iduals. We found no consistent evidence of correlations between traits in levels of FA, nor of any associations between known environmental or developmental conditions. None of the four measures of FA showed a significant heritability (average h2 = 0.041), nor was there any evidence of inbreeding depression. For three of the four traits, fluctuating asymmetry did not predict either annual or lifetime breeding success. However there were significant associations between breeding success and FA in antler length. Given the series of null results in our other tests, it seems likely that this was a direct mechanistic effect rather than because measures of FA were indicative of in idual quality or condition.
Publisher: No publisher found
Publisher: No publisher found
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 08-11-2022
Publisher: American Psychological Association (APA)
Date: 2015
DOI: 10.1037/A0038333
Abstract: Social networks can be important sources of information and insights that may spark employee creativity. The cross-fertilization of ideas depends not just on access to information and insights through one's direct network-the people one actually interacts with--but at least as much on access to the indirect network one's direct ties connect one to (i.e., people one does not interact with directly, but with whom one's direct ties interact). We propose that the reach efficiency of this indirect network--its nonredundancy in terms of interconnections--is positively related to in idual creativity. To help specify the boundaries of this positive influence of the indirect network, we also explore how many steps removed the indirect network still adds to creativity. In addition, we propose that the efficiency (nonredundancy) of one's direct network is important here, because more efficient direct networks give one access to indirect networks with greater reach efficiency. Our hypotheses were supported in a multilevel analysis of multisource survey data from 223 sales representatives nested within 11 isions of a Chinese pharmaceutical company. This analysis also showed that the creative benefits of reach efficiency were evident for 3 and 4 degrees of separation but were greatest for indirect ties that depend only on one's direct ties.
Publisher: No publisher found
Publisher: No publisher found
Publisher: Oxford University Press (OUP)
Date: 02-10-2014
DOI: 10.1534/GENETICS.114.164319
Abstract: Evolutionary theory predicts that genetic constraints should be widespread, but empirical support for their existence is surprisingly rare. Commonly applied univariate and bivariate approaches to detecting genetic constraints can underestimate their prevalence, with important aspects potentially tractable only within a multivariate framework. However, multivariate genetic analyses of data from natural populations are challenging because of modest s le sizes, incomplete pedigrees, and missing data. Here we present results from a study of a comprehensive set of life history traits (juvenile survival, age at first breeding, annual fecundity, and longevity) for both males and females in a wild, pedigreed, population of red deer (Cervus elaphus). We use factor analytic modeling of the genetic variance–covariance matrix (G) to reduce the dimensionality of the problem and take a multivariate approach to estimating genetic constraints. We consider a range of metrics designed to assess the effect of G on the deflection of a predicted response to selection away from the direction of fastest adaptation and on the evolvability of the traits. We found limited support for genetic constraint through genetic covariances between traits, both within sex and between sexes. We discuss these results with respect to other recent findings and to the problems of estimating these parameters for natural populations.
Publisher: No publisher found
Publisher: No publisher found
Publisher: Wiley
Date: 18-03-2010
DOI: 10.1111/J.1558-5646.2010.00991.X
Abstract: Phenotypic plasticity is an important mechanism via which populations can respond to changing environmental conditions, but we know very little about how natural populations vary with respect to plasticity. Here we use random-regression animal models to understand the multivariate phenotypic and genetic patterns of plasticity variation in two key life-history traits, laying date and clutch size, using data from long-term studies of great tits in The Netherlands (Hoge Veluwe [HV]) and UK (Wytham Woods [WW]). We show that, while population-level responses of laying date and clutch size to temperature were similar in the two populations, between-in idual variation in plasticity differed markedly. Both populations showed significant variation in phenotypic plasticity (IxE) for laying date, but IxE was significantly higher in HV than in WW. There were no significant genotype-by-environment interactions (GxE) for laying date, yet differences in GxE were marginally nonsignificant between HV and WW. For clutch size, we only found significant IxE and GxE in WW but no significant difference between populations. From a multivariate perspective, plasticity in laying date was not correlated with plasticity in clutch size in either population. Our results suggest that generalizations about the form and cause of any response to changing environmental conditions across populations may be difficult.
Publisher: No publisher found
DOI: 10.1038/NATURE05912}
Publisher: Wiley
Date: 03-10-2019
DOI: 10.1111/GCB.14831
Abstract: Climate warming has been shown to affect the timing of the onset of breeding of many bird species across the world. However, for multi‐brooded species, climate may also affect the timing of the end of the breeding season, and hence also its duration, and these effects may have consequences for fitness. We used 28 years of field data to investigate the links between climate, timing of breeding, and breeding success in a cooperatively breeding passerine, the superb fairy‐wren ( Malurus cyaneus ). This multi‐brooded species from southeastern Australia has a long breeding season and high variation in phenology between in iduals. By applying a “sliding window” approach, we found that higher minimum temperatures in early spring resulted in an earlier start and a longer duration of breeding, whereas less rainfall and more heatwaves (days 29°C) in late summer resulted in an earlier end and a shorter duration of breeding. Using a hurdle model analysis, we found that earlier start dates did not predict whether or not females produced any young in a season. However, for successful females who produced at least one young, earlier start dates were associated with higher numbers of young produced in a season. Earlier end dates were associated with a higher probability of producing at least one young, presumably because unsuccessful females kept trying when others had ceased. Despite larger scale trends in climate, climate variables in the windows relevant to this species’ phenology did not change across years, and there were no temporal trends in phenology during our study period. Our results illustrate a scenario in which higher temperatures advanced both start and end dates of in iduals’ breeding seasons, but did not generate an overall temporal shift in breeding times. They also suggest that the complexity of selection pressures on breeding phenology in multi‐brooded species may have been underestimated.
Publisher: Wiley
Date: 11-2001
Publisher: No publisher found
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Publisher: No publisher found
DOI: 10.1002/EVL3.79}
Publisher: Springer Science and Business Media LLC
Date: 10-11-2004
Abstract: We present two novel methods to infer mating patterns from genetic data. They differ from existing statistical methods of parentage inference in that they apply to populations that deviate from Hardy-Weinberg and linkage equilibrium, and so are suited for the study of assortative mating in hybrid zones. The core data set consists of genotypes at several loci for a number of full-sib clutches of unknown parentage. Our inference is based throughout on estimates of allelic associations within and across loci, such as heterozygote deficit and pairwise linkage disequilibrium. In the first method, the most likely parents of a given clutch are determined from the genotypic distribution of the associated adult population, given an explicit model of nonrandom mating. This leads to estimates of the strength of assortment. The second approach is based solely on the offspring genotypes and relies on the fact that a linear relation exists between associations among the offspring and those in the population of breeding pairs. We apply both methods to a s le from the hybrid zone between the fire-bellied toads Bombina bombina and B. variegata (Anura: Disco glossidae) in Croatia. Consistently, both approaches provide no evidence for a departure from random mating, despite adequate statistical power. Instead, B. variegata-like in iduals among the adults contributed disproportionately to the offspring cohort, consistent with their preference for the type of breeding habitat in which this study was conducted.
Publisher: Wiley
Date: 12-2006
DOI: 10.1111/J.1461-0248.2006.00989.X
Abstract: Tradeoffs between reproduction and somatic maintenance are a frequently cited explanation for reproductive senescence in long-lived vertebrates. Between-in idual variation in quality makes such tradeoffs difficult to detect and evidence for their presence from wild populations remains scarce. Here, we examine the factors affecting rates of senescence in maternal breeding performance in a natural population of red deer (Cervus elaphus), using a mixed model framework to control for between-in idual variance. Senescence began at 9 years of age in two maternal performance traits. In both traits, females that produced more offspring in early life had faster rates of senescence. This tradeoff is evident alongside significant effects of in idual quality on late life breeding performance. These results present rare evidence in support of the disposable soma and antagonistic pleiotropy theories of senescence from a wild vertebrate population and highlight the utility of mixed models for testing theories of ageing.
Publisher: No publisher found
Publisher: Wiley
Date: 07-2004
Publisher: No publisher found
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-01-2023
Abstract: Climate change may influence animal population dynamics through reproduction and mortality. However, attributing changes in mortality to specific climate variables is challenging because the exact time of death is usually unknown in the wild. Here, we investigated climate effects on adult mortality in Australian superb fairy-wrens ( Malurus cyaneus ). Over a 27-year period, mortality outside the breeding season nearly doubled. This nonbreeding season mortality increased with lower minimum (night-time) and higher maximum (day-time) winter temperatures and with higher summer heat wave intensity. Fine-scale analysis showed that higher mortality in a given week was associated with higher maxima 2 weeks prior and lower minima in the current fortnight, indicating costs of temperature drops. Increases in summer heat waves and in winter maximum temperatures collectively explained 62.6% of the increase in mortality over the study period. Our results suggest that warming climate in both summer and winter can adversely affect survival, with potentially substantial population consequences.
Publisher: Annual Reviews
Date: 12-2008
DOI: 10.1146/ANNUREV.ECOLSYS.39.110707.173542
Abstract: Recent years have seen a rapid expansion in the scope of quantitative genetic analyses undertaken in wild populations. We illustrate here the potential for such studies to address fundamental evolutionary questions about the maintenance of genetic ersity and to reveal hidden genetic conflicts or constraints not apparent at the phenotypic level. Trade-offs between different components of fitness, sexually-antagonistic genetic effects, maternal effects, genotype-by-environment interactions, genotype-by-age interactions, and variation between different regions of the genome in localized genetic correlations may all prevent the erosion of genetic variance. We consider ways in which complex interactions between ecological conditions and the expression of genetic variation can be elucidated, and emphasize the benefits of conducting selection analyses within a quantitative genetic framework. We also review potential developments associated with rapid advances in genomic technology, in particular the increased availability of extensive marker information. Our conclusions highlight the complexity of processes contributing to the maintenance of genetic ersity in wild populations, and underline the value of a quantitative genetic approach in parameterizing models of life-history evolution.
Publisher: No publisher found
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 11-12-2017
Publisher: Springer Science and Business Media LLC
Date: 23-05-2022
Publisher: No publisher found
DOI: 10.1086/648604}
Publisher: The Royal Society
Date: 22-08-1999
Publisher: Springer Science and Business Media LLC
Date: 17-05-2006
Abstract: We investigated phylogeography and spatial genetic structure in an introduced island population of red deer (Cervus elaphus) on the Isle of Rum, Scotland, experiencing spatial variation in management regime. Five different mitochondrial DNA (mtDNA) haplotypes were present among female red deer on Rum. These comprised two phylogenetically ergent groups, one of which clustered with red deer from Sardinia and North Africa, while the other four grouped with other Western European red deer. Recent and historical red deer management practices explain this result. The Rum population is descended from recent introductions from at least four different UK mainland populations, and translocation of red deer within the UK and across Europe is well documented. We found significant spatial genetic structure across Rum in both mtDNA haplotypes and microsatellite markers. Mitochondrial spatial structure was over an order of magnitude greater than structure in nuclear markers. This extreme difference is explained by the fact that the Rum population was introduced from different source populations, the highly male-biased dispersal patterns of red deer and the much smaller effective population size of mitochondrial compared to nuclear markers. Spatial structure in mtDNA conformed to a pattern of isolation by distance, while nuclear DNA did not. Apparent structure in the nuclear markers was driven by differences between the North Block and the rest of the island. We suggest that recent differences in the management regimes in different parts of the island have led to differences in effective male migration that would account for this observation.
Publisher: No publisher found
DOI: 10.1002/ECE3.1945}
Publisher: Hindawi Limited
Date: 25-11-2005
DOI: 10.1017/S0016672305007810
Abstract: The degree to which genetic variation in a given trait varies among different populations of the same species and across different environments has seldom been quantified in wild vertebrate species. We investigated the expression of genetic variability and maternal effects in three larval life-history traits of the hibian Rana temporaria . In a factorial laboratory experiment, five widely separated populations (max. 1600 km) were subjected to two different environmental treatments. Animal model analyses revealed that all traits were heritable ( h 2 ≈0·20) in all populations and under most treatment combinations. Although the cross-food treatment genetic correlations were close to unity, heritabilities under a restricted food regime tended to be lower than those under an ad libitum food regime. Likewise, maternal effects ( m 2 ≈0·05) were detected in most traits, and they tended to be most pronounced under restricted food conditions. We detected several cross-temperature genetic and maternal effects correlations that were lower than unity, suggesting that genotype–environment interactions and maternal effect–environment interactions are a significant source of phenotypic variation. The results reinforce the perspective that although the expression of genetic and maternal effects may be relatively homogeneous across different populations of the same species, local variation in environmental conditions can lead to significant variation in phenotypic expression of quantitative traits through genotype–environment and maternal effect–environment interactions.
Publisher: Public Library of Science (PLoS)
Date: 22-02-2017
Publisher: Springer Science and Business Media LLC
Date: 11-05-2013
Publisher: Wiley
Date: 11-07-2022
Abstract: Climate change presents many challenges for plants, a major one of which is the steady increase in the temperatures that plants are exposed to during germination, growth and reproduction. Generating a more complete understanding of the capacity for plants to respond and of the role that phenotypic plasticity plays in facilitating species' responses to warming temperatures is a central objective in global change ecology. Different traits expressed across life stages might be expected to exhibit a variety of responses to temperature due to phenotypic plasticity and genetic variation, even within a species. However, the extent of the variation among trait types and the relative contribution of plasticity and genetics to responses along a thermal gradient are not well understood. Here, we studied an alpine plant, Wahlenbergia ceracea , to determine the shapes of plastic responses in 14 traits across germination, leaf, physiology and reproductive fitness trait types across a broad thermal gradient of temperatures while also comparing responses among family lines. Trait types differed markedly: germination, leaf and reproductive traits showed nonlinear plasticity with best performance at intermediate temperatures, whereas physiology traits were generally less responsive to temperature. Variation in plasticity among families was lowest for the traits most necessary for tolerating environmental extremes (e.g. heat tolerance), suggesting that physiology traits may be canalised and fitness suffers for it. In contrast, variation in means, and plasticity in some cases, among families in germination traits suggests genetic variation and hence the potential for these few traits to respond to selection. Our results illustrate the variety of responses that may occur in response to temperature, and the frequent occurrence of complex nonlinear plastic responses that would not have been apparent with comparison of fewer temperatures. We discuss the physiological, ecological and evolutionary insights our findings provide into the response of wild species to the changing climate. Read the free Plain Language Summary for this article on the Journal blog.
Publisher: No publisher found
Publisher: No publisher found
DOI: 10.1038/NATURE11335}
Publisher: Wiley
Date: 05-1998
DOI: 10.1046/J.1365-294X.1998.00374.X
Abstract: Paternity inference using highly polymorphic codominant markers is becoming common in the study of natural populations. However, multiple males are often found to be genetically compatible with each offspring tested, even when the probability of excluding an unrelated male is high. While various methods exist for evaluating the likelihood of paternity of each nonexcluded male, interpreting these likelihoods has hitherto been difficult, and no method takes account of the incomplete s ling and error-prone genetic data typical of large-scale studies of natural systems. We derive likelihood ratios for paternity inference with codominant markers taking account of typing error, and define a statistic delta for resolving paternity. Using allele frequencies from the study population in question, a simulation program generates criteria for delta that permit assignment of paternity to the most likely male with a known level of statistical confidence. The simulation takes account of the number of candidate males, the proportion of males that are s led and gaps and errors in genetic data. We explore the potentially confounding effect of relatives and show that the method is robust to their presence under commonly encountered conditions. The method is demonstrated using genetic data from the intensively studied red deer (Cervus elaphus) population on the island of Rum, Scotland. The Windows-based computer program, CERVUS, described in this study is available from the authors. CERVUS can be used to calculate allele frequencies, run simulations and perform parentage analysis using data from all types of codominant markers.
Publisher: No publisher found
Publisher: Cambridge University Press (CUP)
Date: 2017
DOI: 10.1017/ORP.2017.1
Abstract: Many hurdles, such as inadequate resources, impede the execution of strategies in organizations. These problems could partly be ascribed to the tendency of in iduals to feel, in the midst of change, their identity could shift dramatically. Their activities now, therefore, may not seem meaningful to their future. In this state, people become more concerned about their immediate needs, withholding the effort needed to affect future change. Leaders who promote stable, consistent values over time might redress this concern. To assess this possibility, 208 senior managers completed a questionnaire that assesses consistency of values over time, a sense of meaning at work, hurdles that impede the execution of strategy, and firm performance. Consistent with the hypotheses, consistent values over time were positively associated with firm performance, and these relationships were mediated by meaning at work and hurdles that impede strategy. A qualitative study showed that managers utilize many approaches to foster this consistency of values. Specifically, they communicate their strategic plan regularly, redress misalignments between values and practice, encourage the participation of all departments equally, and seek the active support of senior management-all intended to show how perturbations in the organization align to an overarching, enduring vision.
Publisher: No publisher found
Publisher: Elsevier BV
Date: 10-2016
DOI: 10.1016/J.RVSC.2016.08.010
Abstract: Most studies of infectious diseases in East African cattle have concentrated on gastro-intestinal parasites and vector-borne diseases. As a result, relatively little is known about viral diseases, except for those that are clinically symptomatic or which affect international trade such as foot and mouth disease, bluetongue and epizootic haemorrhagic disease. Here, we investigate the seroprevalence, distribution and relationship between the viruses involved in respiratory disease, infectious bovine rhinotracheitis virus (IBR), bovine parainfluenza virus Type 3 (PIV3) and bovine viral diarrhoea virus (BVDV) in East African Shorthorn Zebu calves. These viruses contribute to the bovine respiratory disease complex (BRD) which is responsible for major economic losses in cattle from intensive farming systems as a result of pneumonia. We found that calves experience similar risks of infection for IBR, PIV3, and BVDV with a seroprevalence of 20.9%, 20.1% and 19.8% respectively. We confirm that positive associations exist between IBR, PIV3 and BVDV being seropositive for any one of these three viruses means that an in idual is more likely to be seropositive for the other two viruses than expected by chance.
Publisher: Proceedings of the National Academy of Sciences
Date: 18-01-2000
Abstract: Classical population genetics theory predicts that selection should deplete heritable genetic variance for fitness. We show here that, consistent with this prediction, there was a negative correlation between the heritability of a trait and its association with fitness in a wild population of red deer ( Cervus elaphus ) and there was no evidence of significant heritability of total fitness. However, the decline in heritability was caused, at least in part, by increased levels of residual variance in longevity and, hence, in total fitness: in this population, longevity is known to be heavily influenced by environmental factors. Other life history traits that were not associated with longevity, such as average annual breeding success, had higher heritabilities. Coefficients of additive genetic variance differed markedly between traits, but highly skewed measures, such as male breeding success, generally had greater coefficients of variance than morphometric traits. Finally, there were significant maternal effects in a range of traits, particularly for females.
Publisher: No publisher found
Publisher: No publisher found
Publisher: No publisher found
Publisher: No publisher found
Publisher: Wiley
Date: 05-2006
Publisher: The Royal Society
Date: 07-08-2002
Publisher: Wiley
Date: 04-2009
DOI: 10.1111/J.1558-5646.2009.00625.X
Abstract: Discrete behavioral strategies comprise a suite of traits closely integrated in their expression with consistent natural selection for such coexpression leading to developmental and genetic integration of their components. However, behavioral traits are often also selected to respond rapidly to changing environments, which should both favor their context-dependent expression and inhibit evolution of genetic integration with other, less flexible traits. Here we use a multigeneration pedigree and long-term data on lifetime fitness to test whether behaviors comprising distinct dispersal strategies of western bluebirds-a species in which the propensity to disperse is functionally integrated with aggressive behavior-are genetically correlated. We further investigated whether selection favors flexibility in the expression of aggression in relation to current social context. We found a significant genetic correlation between aggression and dispersal that is concordant with consistent selection for coexpression of these behaviors. To a limited extent, in iduals modified their aggression to match their mate however, we found no fitness consequences on such adjustments. These results introduce a novel way of viewing behavioral strategies, where flexibility of behavior, while often aiding an organism's fit in its current environment, may be limited and thereby enable integration with less flexible traits.
Publisher: Springer Science and Business Media LLC
Date: 06-1999
DOI: 10.1038/20917
Abstract: Many mammal populations show significant deviations from an equal sex ratio at birth, but these effects are notoriously inconsistent. This may be because more than one mechanism affects the sex ratio and the action of these mechanisms depends on environmental conditions. Here we show that the adaptive relationship between maternal dominance and offspring sex ratio previously demonstrated in red deer (Cervus elaphus), where dominant females produced more males, disappeared at high population density. The proportion of males born each year declined with increasing population density and with winter rainfall, both of which are environmental variables associated with nutritional stress during pregnancy. These changes in the sex ratio corresponded to reductions in fecundity, suggesting that they were caused by differential fetal loss. In contrast, the earlier association with maternal dominance is presumed to have been generated pre-implantation. The effects of one source of variation superseded the other within about two generations. Comparison with other ungulate studies indicates that positive associations between maternal quality and the proportion of male offspring born have only been documented in populations below carrying capacity.
Publisher: No publisher found
DOI: 10.1111/JEB.13292}
Publisher: Wiley
Date: 14-01-2011
Publisher: No publisher found
Publisher: The Royal Society
Date: 28-01-2019
Abstract: Phenotypic plasticity is frequently assumed to be an adaptive mechanism by which organisms cope with rapid changes in their environment, such as shifts in temperature regimes owing to climate change. However, despite this adaptive assumption, the nature of selection on plasticity within populations is still poorly documented. Here, we performed a systematic review and meta-analysis of estimates of selection on thermal plasticity. Although there is a large literature on thermal plasticity, we found very few studies that estimated coefficients of selection on measures of plasticity. Those that did do not provide strong support for selection on plasticity, with the majority of estimates of directional selection on plasticity being weak and non-significant, and no evidence for selection on plasticity overall. Although further estimates are clearly needed before general conclusions can be drawn, at present there is not clear empirical support for any assumption that plasticity in response to temperature is under selection. We present a multivariate mixed model approach for robust estimation of selection on plasticity and demonstrate how it can be implemented. Finally, we highlight the need to consider the environments, traits and conditions under which plasticity is (or is not) likely to be under selection, if we are to understand phenotypic responses to rapid environmental change. This article is part of the theme issue ‘The role of plasticity in phenotypic adaptation to rapid environmental change’.
Publisher: No publisher found
DOI: 10.1890/07-1099.1}
Publisher: Oxford University Press (OUP)
Date: 10-2018
DOI: 10.1002/EVL3.79
Abstract: What determines variation between in iduals in how they senesce, and are environmental conditions experienced during development relevant to late-life performance? We report a meta-analysis of studies of wild populations to determine how the quality of the environment experienced during development affects rates of survival and reproductive senescence. From studies of 14 bird or mammal species, we calculated effect sizes for the interaction between the effects of environmental quality during development and age in predicting survival (N = 18) or reproduction (N = 30) over time in late life. We found no evidence that developmental environment affected rates of survival senescence (βmean = –1.2 × 10−4 ± 0.022SE). However, a better developmental environment was associated with slower rates of reproductive senescence in late life (βmean = 0.062 ± 0.023SE), indicating a small, but significant, “silver-spoon” effect of early-life conditions that persisted through to late life. Our results illustrate how the effects of environmental conditions during development can persist throughout life, and indicate one possible cause of phenotypic plasticity in senescence.
Publisher: No publisher found
Publisher: No publisher found
Publisher: Elsevier BV
Date: 05-2003
Publisher: The Royal Society
Date: 07-12-2022
Publisher: Wiley
Date: 03-2004
Publisher: No publisher found
DOI: 10.1098/RSOS.160622}
Publisher: No publisher found
Publisher: No publisher found
DOI: 10.1086/497441}
Publisher: No publisher found
Publisher: No publisher found
DOI: 10.1086/424764}
Publisher: No publisher found
Publisher: The Royal Society
Date: 12-2016
DOI: 10.1098/RSOS.160622
Abstract: Research on relative brain size in mammals suggests that increases in brain size may generate benefits to survival and costs to fecundity: comparative studies of mammals have shown that interspecific differences in relative brain size are positively correlated with longevity and negatively with fecundity. However, as yet, no studies of mammals have investigated whether similar relationships exist within species, nor whether in idual differences in brain size within a wild population are heritable. Here we show that, in a wild population of red deer ( Cervus elaphus ), relative endocranial volume was heritable ( h 2 = 63% 95% credible intervals (CI) = 50–76%). In females, it was positively correlated with longevity and lifetime reproductive success, though there was no evidence that it was associated with fecundity. In males, endocranial volume was not related to longevity, lifetime breeding success or fecundity.
Publisher: Oxford University Press (OUP)
Date: 14-09-2023
Publisher: American Psychological Association (APA)
Date: 11-2012
DOI: 10.1037/A0029359
Abstract: We propose a cross-level perspective on the relation between creative self-efficacy and in idual creativity in which team informational resources, comprising both shared "knowledge of who knows what" (KWKW) and functional background ersity, benefit the creativity of in iduals more with higher creative self-efficacy. To test our hypotheses, we conducted a multi-level study with 176 employees working in 34 research and development teams of a multinational company in 4 countries. In support of our hypotheses, the link between creative self-efficacy and in idual creativity was more positive with greater shared KWKW, and this interactive effect was pronounced for teams of high rather than low functional background ersity. We discuss implications for the study of creative self-efficacy in team contexts.
Publisher: Oxford University Press (OUP)
Date: 06-2019
Abstract: Additive genetic variance in relative fitness (σA2(w)) is arguably the most important evolutionary parameter in a population because, by Fisher’s fundamental theorem of natural selection (FTNS Fisher RA. 1930. The genetical theory of natural selection. 1st ed. Oxford: Clarendon Press), it represents the rate of adaptive evolution. However, to date, there are few estimates of σA2(w) in natural populations. Moreover, most of the available estimates rely on Gaussian assumptions inappropriate for fitness data, with unclear consequences. “Generalized linear animal models” (GLAMs) tend to be more appropriate for fitness data, but they estimate parameters on a transformed (“latent”) scale that is not directly interpretable for inferences on the data scale. Here we exploit the latest theoretical developments to clarify how best to estimate quantitative genetic parameters for fitness. Specifically, we use computer simulations to confirm a recently developed analog of the FTNS in the case when expected fitness follows a log-normal distribution. In this situation, the additive genetic variance in absolute fitness on the latent log-scale (σA2(l)) equals (σA2(w)) on the data scale, which is the rate of adaptation within a generation. However, due to inheritance distortion, the change in mean relative fitness between generations exceeds σA2(l) and equals (exp(σA2(l))−1). We illustrate why the heritability of fitness is generally low and is not a good measure of the rate of adaptation. Finally, we explore how well the relevant parameters can be estimated by animal models, comparing Gaussian models with Poisson GLAMs. Our results illustrate 1) the correspondence between quantitative genetics and population dynamics encapsulated in the FTNS and its log-normal-analog and 2) the appropriate interpretation of GLAM parameter estimates.
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 2005
DOI: 10.1038/NATURE03051
Abstract: Evolutionary theory predicts that local population ergence will depend on the balance between the ersifying effect of selection and the homogenizing effect of gene flow. However, spatial variation in the expression of genetic variation will also generate differential evolutionary responses. Furthermore, if dispersal is non-random it may actually reinforce, rather than counteract, evolutionary differentiation. Here we document the evolution of differences in body mass within a population of great tits, Parus major, inhabiting a single continuous woodland, over a 36-year period. We show that genetic variance for nestling body mass is spatially variable, that this generates different potential responses to selection, and that this ersifying effect is reinforced by non-random dispersal. Matching the patterns of variation, selection and evolution with population ecological data, we argue that the small-scale differentiation is driven by density-related differences in habitat quality affecting settlement decisions. Our data show that when gene flow is not homogeneous, evolutionary differentiation can be rapid and can occur over surprisingly small spatial scales. Our findings have important implications for questions of the scale of adaptation and speciation, and challenge the usual treatment of dispersal as a force opposing evolutionary differentiation.
Publisher: Informa UK Limited
Date: 04-06-2014
Publisher: Wiley
Date: 27-10-2023
Abstract: Climate warming may affect multiple aspects of plant life history, including important factors such as germination responses and the key trade‐off between offspring size and number. As a case study to address these concepts, we used an alpine plant (waxy bluebell, Wahlenbergia ceracea C anulaceae) that shows plasticity to warming in seed traits and in which seed dormancy status regulates germination. We chose an alpine species because alpine environments are ecosystems particularly under threat by climate change. We conducted germination assays under cool and warm temperatures using seeds produced by in iduals that were grown under historical (cooler) and future (warmer) temperature scenarios. We assessed the presence of a seed size versus number trade‐off, and then examined the effects of seed number and size on germination percentage, the fractions of dormant and viable seeds, and germination velocity. Further, we examined whether warming during parental growth and during germination affected these relationships. We found evidence for a seed size versus number trade‐off only under historical parental temperatures. Indeed, under future growth temperatures parental plants produced fewer and smaller seeds and there was no evidence of a trade‐off. However, the reductions in both seed traits under warming did not affect germination, despite correlations of seed size and number with germination traits. Warming increased germination, particularly of larger seeds, but overall, it resulted in more than fourfold reductions in parental fitness. Synthesis . Our study shows the importance of growth conditions when evaluating the seed size versus number trade‐off. Stressful conditions, such as warmer temperatures, can restrain the ability of plants to reach optimal investment in reproduction, masking the trade‐off. By analysing responses across the whole life cycle, we show here an overall detrimental effect of warming, highlighting the potential risk of climate change for Wahlenbergia ceracea , and, potentially, for alpine plant communities more widely.
Publisher: No publisher found
Publisher: Wiley
Date: 07-2007
DOI: 10.1111/J.1558-5646.2007.00128.X
Abstract: Describing natural selection on phenotypic traits under varying environmental conditions is essential for a quantitative assessment of the scale at which adaptation might occur and of the impact of environmental variability on evolution. Here we analyzed patterns of multivariate selection via fecundity and viability on three reproductive traits (laying date, clutch size, and egg weight) in a population of great tits (Parus major). We quantified selection under different environmental conditions using (1) local variation in breeding density and (2) distinct areas of the population's habitat. We found that selection gradients were generally stronger for fecundity than for viability selection. We also found correlational selection acting on the combination of laying date and clutch size this is the first documented evidence of such selection acting on these two traits in a passerine bird. Our analyses showed that both local breeding density and habitat significantly influenced selection patterns, hence favoring different patterns of reproductive investment at a small-scale relative to typical dispersal distances in this species. Canonical rotation of the nonlinear selection matrices yielded similar conclusions as traditional nonlinear selection analyses, and also showed that the main axes of selection and fitness surfaces varied over space within the population. Our results emphasize the importance of quantifying different forms of selection, and of including variation in environmental conditions at small scales to gain a better understanding of potential evolutionary dynamics in wild populations. This study suggests that the fitness landscape for this species is relatively rugged at scales relevant to the life histories of in idual birds and their close relatives.
Publisher: No publisher found
Publisher: Elsevier BV
Date: 12-1999
Publisher: Wiley
Date: 17-06-2011
DOI: 10.1111/J.1420-9101.2011.02334.X
Abstract: The life history schedules of wild organisms have long attracted scientific interest, and, in light of ongoing climate change, an understanding of their genetic and environmental underpinnings is increasingly becoming of applied concern. We used a multi-generation pedigree and detailed phenotypic records, spanning 18 years, to estimate the quantitative genetic influences on the timing of hibernation emergence in a wild population of Columbian ground squirrels (Urocitellus columbianus). Emergence date was significantly heritable [h(2) = 0.22 ± 0.05 (in females) and 0.34 ± 0.14 (in males)], and there was a positive genetic correlation (r(G) = 0.76 ± 0.22) between male and female emergence dates. In adult females, the heritabilities of body mass at emergence and oestrous date were h(2) = 0.23 ± 0.09 and h(2) = 0.18 ± 0.12, respectively. The date of hibernation emergence has been hypothesized to have evolved so as to synchronize subsequent reproduction with upcoming peaks in vegetation abundance. In support of this hypothesis, although levels of phenotypic variance in emergence date were higher than oestrous date, there was a highly significant genetic correlation between the two (r(G) = 0.98 ± 0.01). Hibernation is a prominent feature in the annual cycle of many small mammals, but our understanding of its influences lags behind that for phenological traits in many other taxa. Our results provide the first insight into its quantitative genetic influences and thus help contribute to a more general understanding of its evolutionary significance.
Publisher: Wiley
Date: 05-2010
Publisher: Springer Science and Business Media LLC
Date: 21-10-2006
Publisher: No publisher found
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 28-06-2007
DOI: 10.1038/NATURE05912
Abstract: Evolutionary theory predicts the depletion of genetic variation in natural populations as a result of the effects of selection, but genetic variation is nevertheless abundant for many traits that are under directional or stabilizing selection. Evolutionary geneticists commonly try to explain this paradox with mechanisms that lead to a balance between mutation and selection. However, theoretical predictions of equilibrium genetic variance under mutation-selection balance are usually lower than the observed values, and the reason for this is unknown. The potential role of sexually antagonistic selection in maintaining genetic variation has received little attention in this debate, surprisingly given its potential ubiquity in dioecious organisms. At fitness-related loci, a given genotype may be selected in opposite directions in the two sexes. Such sexually antagonistic selection will reduce the otherwise-expected positive genetic correlation between male and female fitness. Both theory and experimental data suggest that males and females of the same species may have ergent genetic optima, but supporting data from wild populations are still scarce. Here we present evidence for sexually antagonistic fitness variation in a natural population, using data from a long-term study of red deer (Cervus elaphus). We show that male red deer with relatively high fitness fathered, on average, daughters with relatively low fitness. This was due to a negative genetic correlation between estimates of fitness in males and females. In particular, we show that selection favours males that carry low breeding values for female fitness. Our results demonstrate that sexually antagonistic selection can lead to a trade-off between the optimal genotypes for males and females this mechanism will have profound effects on the operation of selection and the maintenance of genetic variation in natural populations.
Publisher: Wiley
Date: 08-06-2020
DOI: 10.1111/EVO.14000
Publisher: The Royal Society
Date: 25-07-2006
Abstract: The impact of environmental change on animal populations is strongly influenced by the ability of in iduals to plastically adjust key life-history events. There is therefore considerable interest in establishing the degree of plasticity in traits and how selection acts on plasticity in natural populations. Breeding time is a key life-history trait that affects fitness and recent studies have found that females vary significantly in their breeding time–environment relationships, with selection often favouring in iduals exhibiting stronger plastic responses. In contrast, here, we show that although breeding time in the common guillemot, Uria aalge , is highly plastic at the population level in response to a large-scale environmental cue (the North Atlantic Oscillation, NAO), there is very little between-in idual variation—most in iduals respond to this climate cue very similarly. We demonstrate strong stabilizing selection against in iduals who deviate from the average population-level response to NAO. This species differs significantly from those previously studied in being a colonial breeder, in which reproductive synchrony has a substantial impact on fitness we suggest that counter selection imposed by a need for synchrony could limit in iduals in their response and potential for directional selection to act. This demonstrates the importance of considering the relative costs and benefits of highly plastic responses in assessing the likely response of a population to the environmental change.
Publisher: No publisher found
Publisher: Cold Spring Harbor Laboratory
Date: 12-10-2016
DOI: 10.1101/079996
Abstract: More than 200 years ago, von Humboldt reported decreases in tropical plant species richness with increasing elevation and decreasing temperature. Surprisingly, co-ordinated patterns in plant, bacterial and fungal ersity on tropical mountains are yet to be observed, despite the central role of soil microorganisms in terrestrial biogeochemistry. We studied an Andean transect traversing 3.5 km in elevation to test whether the species ersity and composition of tropical forest plants, soil bacteria and fungi can follow similar biogeographical patterns with shared environmental drivers. We found co-ordinated changes with elevation in all three groups: species richness declined as elevation increased, and the compositional-dissimilarity of communities increased with increased separation in elevation, although changes in plant ersity were larger than in bacteria and fungi. Temperature was the dominant driver of these ersity gradients, with weak influences of edaphic properties, including soil pH. The gradients in microbial ersity were strongly correlated with the activities of enzymes involved in organic matter cycling, and were accompanied by a transition in microbial traits towards slower-growing, oligotrophic taxa at higher elevations. We provide the first evidence of co-ordinated temperature-driven patterns in the ersity and distribution of three major biotic groups in tropical ecosystems: soil bacteria, fungi and plants. These findings suggest that, across landscape scales of relatively constant soil pH, inter-related patterns of plant and microbial communities with shared environmental drivers can occur, with large implications for tropical forest communities under future climate change.
Publisher: No publisher found
Publisher: Wiley
Date: 27-01-2014
DOI: 10.1002/JOB.1916
Publisher: Academy of Management
Date: 04-2009
Publisher: Oxford University Press (OUP)
Date: 2018
DOI: 10.1534/GENETICS.117.300498
Abstract: To understand how organisms may adapt to environmental changes, it is necessary to determine how environmental conditions influence evolution in wild... How do environmental conditions influence selection and genetic variation in wild populations? There is widespread evidence for selection-by-environment interactions (S*E), but we reviewed studies of natural populations estimating the extent of genotype-by-environment interactions (G*E) in response to natural variation in environmental conditions and found that evidence for G*E appears to be rare within single populations in the wild. Studies estimating the simultaneous impact of environmental variation on both selection and genetic variation are especially scarce. Here, we used 24 years of data collected from a wild Soay sheep population to quantify how an important environmental variable, population density, impacts upon (1) selection through annual contribution to fitness and (2) expression of genetic variation, in six morphological and life history traits: body weight, hind leg length, parasite burden, horn length, horn growth, and testicular circumference. Our results supported the existence of S*E: selection was stronger in years of higher population density for all traits apart from horn growth, with directional selection being stronger under more adverse conditions. Quantitative genetic models revealed significant additive genetic variance for body weight, leg length, parasite burden, horn length, and testes size, but not for horn growth or our measure of annual fitness. However, random regression models found variation between in iduals in their responses to the environment in only three traits, and did not support the presence of G*E for any trait. Our analyses of St Kilda Soay sheep data thus concurs with our cross-study review that, while natural environmental variation within a population can profoundly alter the strength of selection on phenotypic traits, there is less evidence for its effect on the expression of genetic variance in the wild.
Publisher: Wiley
Date: 26-10-2018
DOI: 10.1002/ECY.2482
Publisher: No publisher found
Publisher: The Royal Society
Date: 03-06-2009
Abstract: Males and females often have different requirements during early development, leading to sex-specific interactions between developing offspring. In polytocous mammals, competition for limited resources in utero may be asymmetrical between the sexes, and androgens produced by male foetuses could have adverse effects on the development of females, with potentially long-lasting consequences. We show here, in an unmanaged population of Soay sheep, that female lambs with a male co-twin have reduced birth weight relative to those with a female co-twin, while there was no such effect in male twins. In addition, females with a male co-twin had lower lifetime breeding success, which appeared to be mainly driven by differences in first-year survival. These results show that sex-specific sibling interactions can have long-term consequences for survival and reproduction, with potentially important implications for optimal sex allocation.
Publisher: Wiley
Date: 05-12-2018
DOI: 10.1111/IMIG.12415
Publisher: Wiley
Date: 12-05-2020
DOI: 10.1111/JBI.13850
Publisher: No publisher found
Publisher: No publisher found
Publisher: John Wiley & Sons Ltd
Date: 16-04-2008
Publisher: No publisher found
Publisher: SAGE Publications
Date: 29-07-2015
Abstract: In response to calls for multilevel research examining in idual and meso-level processes to understand how exploitation and exploration dynamics play out in teams, we propose that in idual in-role performance (cf. exploitation) and creativity (cf. exploration) are associated with team exploitation and exploration climate respectively, and this influence is moderated by domain specific performance and creative self-efficacy respectively. Studying 317 engineers in 70 teams across three national regions, we theorize and find domain-specific evidence that when in idual self-efficacy is high, team climate has diminishing performance (exploitation climate × performance self-efficacy) and creative (exploration climate × creative self-efficacy) benefits. By simultaneously studying creativity and performance, our study helps understand the differences and communalities in the drivers of those outcomes in identifying both the domain-specific character of these influences and the similarity in how these influences play out.
Publisher: Elsevier BV
Date: 05-2008
DOI: 10.1016/J.CUB.2008.04.059
Abstract: In any population in which resources are limiting, the allocation of resources toward increased reproductive success may generate costs to survival [1-8]. The relationship between a sexually selected trait and fitness will therefore represent a balance between its relative associations with fecundity versus viability [3, 6, 7]. Because the risk of mortality in a population is likely to be heavily determined by ecological conditions, survival costs may vary as a function of the prevailing environment [7]. As a result, for populations experiencing heterogeneous ecological conditions, there may not be a single optimal level of allocation toward reproduction versus survival [9]. Here, we show that early viability and fecundity selection act in opposing directions on a secondary sexual trait and that their relative magnitude depends upon ecological conditions, generating fluctuating selection. In a wild population of Soay sheep (Ovis aries), phenotypic and genetic associations between male horn growth and lifetime reproductive success were positive under good environmental conditions (because of increased breeding success) and negative under poor environmental conditions (because of reduced survival). In an unpredictable environment, high allocation to early horn growth is a gamble that will only pay off if ensuing conditions are favorable. Such fluctuating selection may play an important role in preventing the erosion of genetic variance in secondary sexual traits.
Publisher: Oxford University Press (OUP)
Date: 04-2011
DOI: 10.1534/GENETICS.110.124990
Abstract: Cryptic evolution has been defined as adaptive evolutionary change being masked by concurrent environmental change. Empirical studies of cryptic evolution have usually invoked a changing climate and/or increasing population density as the form of detrimental environmental change experienced by a population undergoing cryptic evolution. However, Fisher (1958) emphasized that evolutionary change in itself is likely to be an important component of “environmental deterioration,” a point restated by Cookeet al. (1990) in the context of intraspecific competition. In this form, environmental deterioration arises because a winning lineage has to compete against more winners in successive generations as the population evolves. This “evolutionary environmental deterioration” has different implications for the selection and evolution of traits influenced by resource competition than general environmental change. We reformulate Cooke's model as a quantitative genetic model to show that it is identical in form to more recent developments proposed by quantitative geneticists. This provides a statistical framework for discriminating between the alternative hypotheses of environmental change and environmental deterioration caused by evolutionary change. We also demonstrate that in systems where no phenotypic change has occurred, there are many reasonable biological processes that will generate patterns in predicted breeding values that are consistent with what has been interpreted as cryptic evolution, and care needs to be taken when interpreting these patterns. These processes include mutation, sib competition, and invisible fractions.
Publisher: Wiley
Date: 10-06-2011
DOI: 10.1111/J.1420-9101.2011.02300.X
Abstract: Parasites detrimentally affect host fitness, leading to expectations of positive selection on host parasite resistance. However, as immunity is costly, host fitness may be maximized at low, but nonzero, parasite infection intensities. These hypotheses are rarely tested on natural variation in free-living populations. We investigated selection on a measure of host parasite resistance in a naturally regulated Soay sheep population using a longitudinal data set and found negative correlations between parasite infection intensity and annual fitness in lambs, male yearlings and adult females. However, having accounted for confounding effects of body weight, the effect was only significant in lambs. Associations between fitness and parasite resistance were environment-dependent, being strong during low-mortality winters, but negligible during harsher high-mortality winters. There was no evidence for stabilizing selection. Our findings reveal processes that may shape variation in parasite resistance in natural populations and illustrate the importance of accounting for correlated traits in selection analysis.
Publisher: No publisher found
Publisher: Wiley
Date: 06-2008
DOI: 10.1890/07-1099.1
Abstract: Two contrasting approaches to the analysis of population dynamics are currently popular: demographic approaches where the associations between demographic rates and statistics summarizing the population dynamics are identified and time series approaches where the associations between population dynamics, population density, and environmental covariates are investigated. In this paper, we develop an approach to combine these methods and apply it to detailed data from Soay sheep (Ovis aries). We examine how density dependence and climate contribute to fluctuations in population size via age- and sex-specific demographic rates, and how fluctuations in demographic structure influence population dynamics. Density dependence contributes most, followed by climatic variation, age structure fluctuations and interactions between density and climate. We then simplify the density-dependent, stochastic, age-structured demographic model and derive a new phenomenological time series which captures the dynamics better than previously selected functions. The simple method we develop has potential to provide substantial insight into the relative contributions of population and in idual-level processes to the dynamics of populations in stochastic environments.
Publisher: The Royal Society
Date: 05-08-2005
Abstract: Influences of climate on life history traits in natural populations are well documented. However, the implications of between-in idual variation in phenotypic plasticity underlying observed trait–environment relationships are rarely considered due to the large, long-term datasets required for such analysis. Studies typically present correlations of annual trait means with climate or assume that in idual phenotypic responses are constant. Here, we examine this additional level of variation and show that, in a red deer population on the Isle of Rum, Scotland, changes in climate generate changes in phenotype only amongst in iduals who have experienced favourable ecological conditions. Examination of relationships between offspring birth weight and spring temperature within the lifetimes of in idual females revealed that the tendency to respond to climate declined as the population density experienced early in life increased. The presence of such systematic variation in in idual plasticity is rarely documented in the wild, and has important implications for our understanding of the environmental dependencies of traits under varying ecological conditions.
Publisher: No publisher found
Publisher: No publisher found
DOI: 10.1038/NATURE03051}
Publisher: The Royal Society
Date: 22-08-2000
Publisher: American Association for the Advancement of Science (AAAS)
Date: 27-05-2022
Abstract: The rate of adaptive evolution, the contribution of selection to genetic changes that increase mean fitness, is determined by the additive genetic variance in in idual relative fitness. To date, there are few robust estimates of this parameter for natural populations, and it is therefore unclear whether adaptive evolution can play a meaningful role in short-term population dynamics. We developed and applied quantitative genetic methods to long-term datasets from 19 wild bird and mammal populations and found that, while estimates vary between populations, additive genetic variance in relative fitness is often substantial and, on average, twice that of previous estimates. We show that these rates of contemporary adaptive evolution can affect population dynamics and hence that natural selection has the potential to partly mitigate effects of current environmental change.
Publisher: SAGE Publications
Date: 25-10-2021
DOI: 10.1177/15480518211044166
Abstract: Most prior research has examined procrastination as a type of self-defeating behavior. The present research, however, focused on the social consequences of procrastination, by investigating how decisional leader procrastination as a leader trait affects others in the workplace. We specifically developed the argument that the way in which employees deal with changes plays a critical moderating role in the relationship between leader procrastination and employee innovation. More precisely, we hypothesized that decisional leader procrastination negatively impacts employee innovation, but only so for employees who are low (compared to high) in resistance to change. This prediction was tested in an experimental study (Study 1) and two double-source survey studies (Studies 2 and 3). In support of our prediction, the results showed that an indecisive leader indeed undermines the innovation of those employees who embrace—rather than resist—changes. Critically, however, our findings also illustrated that when being supervised by a decisive leader, these particular employees are actually most likely to bring forward the process of innovation. Theoretical and practical implications of our results are discussed.
Publisher: No publisher found
DOI: 10.1038/35083580}
Publisher: Springer Science and Business Media LLC
Date: 08-08-2012
DOI: 10.1038/NATURE11335
Abstract: The most commonly reported ecological effects of climate change are shifts in phenologies, in particular of warmer spring temperatures leading to earlier timing of key events. Among animals, however, these reports have been heavily biased towards avian phenologies, whereas we still know comparatively little about other seasonal adaptations, such as mammalian hibernation. Here we show a significant delay (0.47 days per year, over a 20-year period) in the hibernation emergence date of adult females in a wild population of Columbian ground squirrels in Alberta, Canada. This finding was related to the climatic conditions at our study location: owing to within-in idual phenotypic plasticity, females emerged later during years of lower spring temperature and delayed snowmelt. Although there has not been a significant annual trend in spring temperature, the date of snowmelt has become progressively later owing to an increasing prevalence of late-season snowstorms. Importantly, years of later emergence were also associated with decreased in idual fitness. There has consequently been a decline in mean fitness (that is, population growth rate) across the past two decades. Our results show that plastic responses to climate change may be driven by climatic trends other than increasing temperature, and may be associated with declines in in idual fitness and, hence, population viability.
Publisher: The Royal Society
Date: 09-03-2020
Abstract: By the Robertson–Price identity, the change in a quantitative trait owing to selection, is equal to the trait's covariance with relative fitness. In this study, we applied the identity to long-term data on superb fairy-wrens Malurus cyaneus , to estimate phenotypic and genetic change owing to juvenile viability selection. Mortality in the four-week period between fledging and independence was 40%, and heavier nestlings were more likely to survive, but why? There was additive genetic variance for both nestling mass and survival, and a positive phenotypic covariance between the traits, but no evidence of additive genetic covariance. Comparing standardized gradients, the phenotypic selection gradient was positive, β P = 0.108 (0.036, 0.187 95% CI), whereas the genetic gradient was not different from zero, β A = −0.025 (−0.19, 0.107 95% CI). This suggests that factors other than nestling mass were the cause of variation in survival. In particular, there were temporal correlations between mass and survival both within and between years. We suggest that use of the Price equation to describe cross-generational change in the wild may be challenging, but a more modest aim of estimating its first term, the Robertson–Price identity, to assess within-generation change can provide valuable insights into the processes shaping phenotypic ersity in natural populations. This article is part of the theme issue ‘Fifty years of the Price equation’.
Publisher: No publisher found
Publisher: Wiley
Date: 03-12-2012
Publisher: Elsevier BV
Date: 12-2007
Publisher: Oxford University Press (OUP)
Date: 08-12-2017
Publisher: No publisher found
DOI: 10.1111/EVO.13496}
Publisher: Wiley
Date: 27-03-2014
Publisher: Proceedings of the National Academy of Sciences
Date: 15-03-2016
Abstract: Inbreeding depression is the decrease in fitness with increased genome-wide homozygosity that occurs in the offspring of related parents. Estimation of its effect in wild populations has been challenging, and while evidence of inbreeding depression in juvenile traits is widespread, ex les during later life stages remain rare. Here, in a species with extended maternal care, genomic inbreeding coefficients, but not pedigree-based ones, revealed inbreeding depression in annual breeding success in both sexes, and in offspring rearing success in females. This contributed to inbreeding depression in estimates of lifetime fitness in both sexes. Our work illustrates that inbreeding depression in adult traits can be as large as in juvenile traits but requires more powerful methods to be detected.
Publisher: Wiley
Date: 23-12-2003
DOI: 10.1046/J.1420-9101.2003.00655.X
Abstract: Theory predicts that natural selection will erode additive genetic variation in fitness-related traits. However, numerous studies have found considerable heritable variation in traits related to immune function, which should be closely linked to fitness. This could be due to trade-offs maintaining variation in these traits. We used the Egyptian cotton leafworm, Spodoptera littoralis, as a model system to examine the quantitative genetics of insect immune function. We estimated the heritabilities of several different measures of innate immunity and the genetic correlations between these immune traits and a number of life history traits. Our results provide the first evidence for a potential genetic trade-off within the insect immune system, with antibacterial activity (lysozyme-like) exhibiting a significant negative genetic correlation with haemocyte density, which itself is positively genetically correlated with both haemolymph phenoloxidase activity and cuticular melanization. We speculate on a potential trade-off between defence against parasites and predators, mediated by larval colour, and its role in maintaining genetic variation in traits under natural selection.
Publisher: No publisher found
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 2011
Publisher: Elsevier BV
Date: 12-2007
DOI: 10.1016/J.CUB.2007.11.043
Abstract: Aging, or senescence, defined as a decline in physiological function with age, has long been a focus of research interest for evolutionary biologists. How has natural selection failed to remove genetic effects responsible for such reduced fitness among older in iduals? Current evolutionary theory explains this phenomenon by showing that, as a result of the risk of death from environmental causes that in iduals experience, the force of selection inevitably weakens with age. This in turn means that genetic mutations having detrimental effects that are only felt late in life might persist in a population. Although widely accepted, this theory rests on the assumption that there is genetic variation for aging in natural systems, or (equivalently), that genotype-by-age interactions (GxA) occur for fitness. To date, empirical support for this assumption has come almost entirely from laboratory studies on invertebrate systems, most notably Drosophila and C. elegans, whereas tests of genetic variation for aging are largely lacking from natural populations. By using data from two wild mammal populations, we perform quantitative genetic analyses of fitness and provide the first evidence for a genetic basis of senescence to come from a study in the natural environment. We find evidence that genetic differences among in iduals cause variation in their rates of aging and that additive genetic variance for fitness increases with age, as predicted by the evolutionary theory of senescence.
Publisher: No publisher found
Publisher: Annual Reviews
Date: 02-11-2022
DOI: 10.1146/ANNUREV-ECOLSYS-012722-024041
Abstract: Long-term studies of in iduals enable incisive investigations of questions across ecology and evolution. Here, we illustrate this claim by reference to our long-term study of red deer on the Isle of Rum, Scotland. This project has established many of the characteristics of social organization, selection, and population ecology typical of large, polygynous, seasonally breeding mammals, with wider implications for our understanding of sexual selection and the evolution of sex differences, as well as for their population dynamics and population management. As molecular genetic techniques have developed, the project has pivoted to investigate evolutionary genetic questions, also breaking new ground in this field. With ongoing advances in genomics and statistical approaches and the development of increasingly sophisticated ways to assay new phenotypic traits, the questions that long-term studies such as the red deer study can answer become both broader and ever more sophisticated. They also offer powerful means of understanding the effects of ongoing climate change on wild populations.
Publisher: Elsevier BV
Date: 06-2004
Publisher: No publisher found
Publisher: No publisher found
DOI: 10.1038/20917}
Publisher: American Association for the Advancement of Science (AAAS)
Date: 06-03-2015
Abstract: Highly protective effect of co-infections on mortality due to East Coast fever and consequences for disease epidemiology and control.
Publisher: Springer Science and Business Media LLC
Date: 22-02-2015
Publisher: Wiley
Date: 03-2007
Publisher: The Royal Society
Date: 22-01-1997
Publisher: American Psychological Association (APA)
Date: 03-2023
DOI: 10.1037/GDN0000188
Publisher: Wiley
Date: 19-04-2021
Abstract: Employment underpins the successful resettlement and integration of refugees, and human resource (HR) professionals are integral to successful employee–employer relationships. Until recently, research has largely overlooked the role of HR professionals in the recruitment and integration of employees at work. Reviewing the literature on refugee employment through an HR lens, this review offers insights and practical solutions that contribute to the effective recruitment and workplace integration of refugees. We identify strategies such as onboarding programs, job enrichment and internships that offer realistic job previews, and the opportunity for people from a refugee background to validate and demonstrate their credentials. In addition, we describe the benefits of organisations’ engagement in external relationship management to ch ion changes in industrial relations and foster cross‐sector partnerships that aid refugee employment. In the discussion, we describe the practical implications of our review, and highlight directions for future research that addresses different stakeholder needs and priorities.
Publisher: No publisher found
Publisher: University of Chicago Press
Date: 12-2001
DOI: 10.1086/323585
Abstract: One of evolutionary biology's most persistent puzzles is the fact that apparent directional selection on a heritable trait in a natural population often does not produce a selection response. We tested three possible explanations for this problem using data on body size of more than 23,000 in iduals, measured over 18 yr, in a collared flycatcher (Ficedula albicollis) population. Using a restricted maximum likelihood "animal model," we found a narrow-sense heritability for fledgling tarsus length of [Formula: see text] SE and substantial common environment effects ([Formula: see text] SE). For survival to adulthood, the selection differential on tarsus length was [Formula: see text] SE. There was, however, no response to this selection over the study period. One explanation for the lack of response might have been that selection was associated with only the environmental (nonheritable) component of phenotype, but we found significant selection on breeding values (the heritable component). There was also no evidence of fluctuating selection pressures or of antagonistic selection between the sexes in selection pressures. Thus, in contrast to earlier investigations in this same population, none of the potential explanations for the absence of a selection response was supported we discuss alternative hypotheses yet to be investigated.
Publisher: No publisher found
DOI: 10.1086/524957}
Publisher: Wiley
Date: 05-01-2002
DOI: 10.1046/J.1365-2869.1999.00163.X
Abstract: A large litude late negative deflection peaking between 500 and 650 ms is observable in the averaged K-complex wave-form. This peak is thus often labelled the N550. 'N550' appears during stage 2 and is maintained into slow wave sleep but is not apparent during REM. Most studies have employed auditory stimuli to elicit the K-complex. Two experiments were run to examine the effects of stimulus modality on the topographical distribution of the N550. In the first experiment, the K-complexes were elicited in an auditory oddball procedure. In the second experiment, K-complexes were elicited by respiratory occlusions. Twenty-nine channel recordings were used to increase spatial resolution. N550 was substantially larger in the average of trials containing K-complexes than in trials in which a K-complex could not be identified. N550 varied inversely in litude with the probability of accordance of the stimulus. The topographic distribution of the N550 was consistent between experiments. It was bilaterally symmetrical and was maximal over fronto-central regions of the scalp. The results indicate that the N550 reflects the activity of a modality non-specific, sleep dependent generator that responds to both interoceptive and external stimulation.
Publisher: Wiley
Date: 25-01-2019
DOI: 10.1111/NPH.15656
Abstract: Contents Summary 1235 I. Introduction 1235 II. The many shapes of phenotypic plasticity 1236 III. Random regression mixed model framework 1237 IV. Conclusions 1240 Acknowledgements 1240 References 1240 SUMMARY: Plant biology is experiencing a renewed interest in the mechanistic underpinnings and evolution of phenotypic plasticity that calls for a re-evaluation of how we analyse phenotypic responses to a rapidly changing climate. We suggest that dissecting plant plasticity in response to increasing temperature needs an approach that can represent plasticity over multiple environments, and considers both population-level responses and the variation between genotypes in their response. Here, we outline how a random regression mixed model framework can be applied to plastic traits that show linear or nonlinear responses to temperature. Random regressions provide a powerful and efficient means of characterising plasticity and its variation. Although they have been used widely in other fields, they have only recently been implemented in plant evolutionary ecology. We outline their structure and provide an ex le tutorial of their implementation.
Publisher: No publisher found
Publisher: Wiley
Date: 15-06-2007
DOI: 10.1111/J.1420-9101.2007.01377.X
Abstract: Related in iduals often have similar phenotypes, but this similarity may be due to the effects of shared environments as much as to the effects of shared genes. We consider here alternative approaches to separating the relative contributions of these two sources to phenotypic covariances, comparing experimental approaches such as cross-fostering, traditional statistical techniques and more complex statistical models, specifically the 'animal model'. Using both simulation studies and empirical data from wild populations, we demonstrate the ability of the animal model to reduce bias due to shared environment effects such as maternal or brood effects, especially where pedigrees contain multiple generations and immigration rates are low. However, where common environment effects are strong, a combination of both cross-fostering and an animal model provides the best way to avoid bias. We illustrate ways of partitioning phenotypic variance into components of additive genetic, maternal genetic, maternal environment, common environment, permanent environment and temporal effects, but also show how substantial confounding between these different effects may occur. Whilst the flexibility of the mixed model approach is extremely useful for incorporating the spatial, temporal and social heterogeneity typical of natural populations, the advantages will inevitably be restricted by the quality of pedigree information and care needs to be taken in specifying models that are appropriate to the data.
Publisher: No publisher found
Publisher: No publisher found
Publisher: Wiley
Date: 28-04-2005
Publisher: Wiley
Date: 27-10-2004
DOI: 10.1111/J.1420-9101.2004.00824.X
Abstract: Heritable maternal effects have important consequences for the evolutionary dynamics of phenotypic traits under selection, but have only rarely been tested for or quantified in evolutionary studies. Here we estimate maternal effects on early-life traits in a feral population of Soay sheep (Ovis aries) from St Kilda, Scotland. We then partition the maternal effects into genetic and environmental components to obtain the first direct estimates of maternal genetic effects in a free-living population, and furthermore test for covariance between direct and maternal genetic effects. Using an animal model approach, direct heritabilities (h2) were low but maternal genetic effects (m2) represented a relatively large proportion of the total phenotypic variance for each trait (birth weight m2=0.119, birth date m2=0.197, natal litter size m2=0.211). A negative correlation between direct and maternal genetic effects was estimated for each trait, but was only statistically significant for natal litter size (ram= -0.714). Total heritabilities (incorporating variance from heritable maternal effects and the direct-maternal genetic covariance) were significant for birth weight and birth date but not for natal litter size. Inadequately specified models greatly overestimated additive genetic variance and hence direct h2 (by a factor of up to 6.45 in the case of birth date). We conclude that failure to model heritable maternal variance can result in over- or under-estimation of the potential for traits to respond to selection, and advocate an increased effort to explicitly measure maternal genetic effects in evolutionary studies.
Publisher: No publisher found
Publisher: No publisher found
Publisher: No publisher found
Publisher: No publisher found
Publisher: SAGE Publications
Date: 23-05-2020
Abstract: Agency is the human capability to exert influence over one’s actions and environment, such as through forethought, self-regulation and self-reflection. We focus on six prominent agency constructs, including goal orientation, regulatory focus, proactivity, fear of failure, core self-evaluations and psychological capital, and review what we have learned from each construct. By adopting an overarching multidisciplinary perspective, we identify key research agendas for the six prominent constructs: (1) incorporating self-reflection into research on agentic disposition (2) how agency dispositions equip employees for workplaces of the futures, yet also how such behaviours may challenge societal and corporate mechanisms of control and (3) well-being and health-related consequences of agency. In addition, we highlight the importance of understanding the interface between agency scholarship and developments in technology, medicine and sociology. JEL Classification: M10, M14
Publisher: No publisher found
Publisher: Proceedings of the National Academy of Sciences
Date: 08-02-2005
Abstract: An increasing number of studies have documented phenotypic selection on life-history traits in human populations, but less is known of the heritability and genetic constraints that mediate the response to selection on life-history traits in humans. We collected pedigree data for four generations of preindustrial (1745–1900) Finns who lived in premodern fertility and mortality conditions, and by using a restricted maximum-likelihood animal-model framework, we estimated the heritability of and genetic correlations between a suite of life-history traits and two alternative measures of fitness. First, we demonstrate high heritability of key life-history traits (fecundity, interbirth interval, age at last reproduction, and adult longevity) and measures of fitness (in idual λ and lifetime reproductive success) for females but not for males. This sex difference may have arisen because most of the measured traits are under physiological control of the female, such that a male's fitness in monogamous societies may depend mainly on the reproductive quality of his spouse. We found strong positive genetic correlations between female age at first reproduction and longevity, and between interbirth intervals and longevity, suggesting reduced life spans in females who either started to breed relatively early or who then bred frequently. Our results suggest that key female life-history traits in this premodern human population had high heritability and may have responded to natural selection. However genetic constraints between longevity and reproductive life-history traits may have constrained the evolution of life history and facilitated the maintenance of additive genetic variance in key life-history traits.
Publisher: No publisher found
Publisher: American Psychological Association (APA)
Date: 06-2022
DOI: 10.1037/APL0000960
Abstract: The benefits boundary spanners offer organizations by bridging information silos are well documented. However, informational boundary spanning also implies crossing organizational territories, as employees seek advice from others outside their supervisors' control. Applying a territoriality theory lens, we develop new insights about when and why supervisors may view their subordinates' informational boundary-spanning activities unfavorably and attempt to undermine boundary spanners. We argue that undermining results from supervisors perceiving the boundary spanning of their employees as weakening their control over their organizational territory. We further argue that subordinates who seek advice across organizational boundaries without also seeking advice from their supervisor are more likely to be seen by their supervisors as having negative intentions when engaging in boundary spanning, which increases their risk of being undermined. We find support for our arguments in a field study and in a scenario experiment. Our results provide new insights into the potentially negative reactions from supervisors toward employees who engage in boundary spanning. We discuss how these insights contribute to the boundary spanning literature, to territoriality theory, and to the leadership literature. (PsycInfo Database Record (c) 2022 APA, all rights reserved).
Publisher: Wiley
Date: 10-1999
DOI: 10.1111/J.1558-5646.1999.TB05425.X
Abstract: Reproductive isolation between two taxa may be due to endogenous selection, which is generated by incompatibilities between the respective genomes, to exogenous selection, which is generated by differential adaptations to alternative environments, or to both. The continuing debate over the relative importance of either mode of selection has highlighted the need for unambiguous data on the fitness of hybrid genotypes. The hybrid zone between the fire-bellied toad (Bombina bombina) and the yellow-bellied toad (B. variegata) in central Europe involves adaptation to different environments, but evidence of hybrid dysfunction is equivocal. In this study, we followed the development under laboratory conditions of naturally laid eggs collected from a transect across the Bombina hybrid zone in Croatia. Fitness was significantly reduced in hybrid populations: Egg batches from the center of the hybrid zone showed significantly higher embryonic and larval mortality and higher frequencies of morphological abnormalities relative to either parental type. Overall mortality from day of egg collection to three weeks after hatching reached 20% in central hybrid populations, compared to 2% in pure populations. There was no significant difference in fitness between two parental types. Within hybrid populations, there was considerable variation in fitness, with some genotypes showing no evidence of reduced viability. We discuss the implications of these findings for our understanding of barriers to gene flow between species.
Publisher: No publisher found
Publisher: The Royal Society
Date: 08-07-2009
Abstract: Despite widespread empirical evidence for a general deterioration in the majority of traits with advancing age, it is unclear whether the progress of senescence is chronologically determined, or whether factors such as environmental conditions experienced over the lifespan are more important. We explored the relative importance of ‘chronological’ and ‘environmental’ measures of age to changes in parasite resistance across the lifespan of free-living Soay sheep. Our results show that in iduals experience an increase in parasite burden, as indicated by gastrointestinal helminth faecal egg count (FEC) with chronological age. However, chronological age fails to fully explain changes in FEC because a measure of environmental age, cumulative environmental stress, predicts an additional increase in FEC once chronological age has been accounted for. Additionally, we show that in females age-specific changes are dependent upon the environmental conditions experienced across in iduals' life histories: increases in FEC with age were greatest among in iduals that had experienced the highest degree of stress. Our results illustrate that chronological age alone may not always correspond to biological age, particularly in variable environments. In these circumstances, measures of age that capture the cumulative stresses experienced by an in idual may be useful for understanding the process of senescence.
Publisher: Wiley
Date: 10-2006
Publisher: No publisher found
Publisher: Cambridge University Press (CUP)
Date: 04-1996
DOI: 10.1017/S0007485300052391
Abstract: Outbreaks of the winter moth, Operophtera brumata Linnaeus (Lepidoptera: Geometridae), have recently become widespread on heather moorlands in northeast Scotland. These outbreaks represent remarkable phenomena given the poor nutritional quality of the dominant moorland host plant Calluna vulgaris (Linnaeus) Hull (Ericaceae). Winter moth performance on C. vulgaris was compared with that on the other available moorland host plant, Vaccinium myrtillus (Linnaeus) (Ericaceae), and parasitism levels were measured in two moorland outbreak populations. Larval densities in the field were generally higher on Calluna than on Vaccinium . However, larvae showed better survival, more rapid development and greater pupal weights on Vaccinium than on Calluna . Feeding trials indicated that Vaccinium was more digestible than Calluna . No evidence of parasitism was found in a high-altitude moorland winter moth outbreak population from mainland Scotland, but the parasitoid Phoboc e neglecta (Holmgren) (Hymenoptera: Ichneumonidae) was present in 27% of larvae from a lower-altitude moorland outbreak on Orkney. The results indicate that the presence of Vaccinium and the opportunity to escape from parasitism may facilitate O. brumata outbreak formation in high-altitude moorland sites. However, neither factor can provide a full explanation for the present phenomenon.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 26-01-2018
Abstract: The comment by Myers-Smith and Myers focuses on three main points: (i) the lack of a mechanistic explanation for climate-selection relationships, (ii) the appropriateness of the climate data used in our analysis, and (iii) our focus on estimating climate-selection relationships across (rather than within) taxonomic groups. We address these critiques in our response.
Publisher: The Royal Society
Date: 08-2015
Abstract: Mothers vary in their effects on their offspring, but studies of variation in maternal effects rarely ask whether differences between mothers are consistent for sons and daughters. Here, we analysed maternal effects in the mosquitofish Gambusia holbrooki for development time and adult size of sons and daughters, and a primary male sexual character (gonopodium length). We found substantial maternal effects on all traits, most notably for gonopodium length. There were significant correlations within each sex for maternal effects on different traits, indicative of trade-offs between development rate and adult size. By contrast, there was no evidence of any consistency in maternal effects on sons and daughters. This suggests that the evolution of maternal effects will follow independent trajectories dependent on sex-specific selection on offspring. Importantly, failure to recognize the sex-specific nature of maternal effects in this population would have substantially underestimated the extent of their variation between mothers.
Publisher: Wiley
Date: 03-2005
Publisher: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.YGCEN.2015.07.009
Abstract: Although it is known that hormone concentrations vary considerably between in iduals within a population, how they change across time and how they relate to an in idual's reproductive effort remains poorly quantified in wild animals. Using faecal s les collected from wild red deer stags, we examined sources of variation in faecal cortisol and androgen metabolites, and the potential relationship that these might have with an index of reproductive effort. We also biologically validated an assay for measuring androgen metabolites in red deer faeces. We show that variation in hormone concentrations between s les can be accounted for by the age of the in idual and the season when the s le was collected. Faecal cortisol (but not androgen) metabolites also showed significant among-in idual variation across the 10-year s ling time period, which accounted for 20% of the trait's phenotypic variance after correcting for the age and season effects. Finally, we show that an index of male reproductive effort (cumulative harem size) during the mating season (rut) was positively correlated with male cortisol concentrations, both among and within in iduals. We suggest that the highest ranking males have the largest cumulative harem sizes (i.e. invest the greatest reproductive effort), and that this social dominance may have associated behaviours such as increased frequency of agonistic interactions which are associated with corresponding high levels of faecal cortisol metabolites (FCM).
Publisher: No publisher found
Publisher: No publisher found
Publisher: The Royal Society
Date: 25-02-2009
Abstract: For multiple-brooded species, the number of reproductive events per year is a major determinant of an in idual's fitness. Where multiple brooding is facultative, its occurrence is likely to change with environmental conditions, and, as a consequence, the current rates of environmental change could have substantial impacts on breeding patterns. Here we examine temporal population-level trends in the proportion of female great tits ( Parus major ) producing two clutches per year (‘double brooding’) in four long-term study populations in The Netherlands, and show that the proportion of females that double brood has declined in all populations, with the strongest decline taking place in the last 30 years of the study. For one of the populations, for which we have data on caterpillar abundance, we show that the probability that a female produces a second clutch was related to the timing of her first clutch relative to the peak in caterpillar abundance, and that the probability of double brooding declined over the study period. We further show that the number of recruits from the second clutch decreased significantly over the period 1973–2004 in all populations. Our results indicate that adjustment to changing climatic conditions may involve shifts in life-history traits other than simply the timing of breeding.
Publisher: Cambridge University Press (CUP)
Date: 18-09-2006
DOI: 10.1017/S0031182006001144
Abstract: The feral Soay sheep ( Ovis aries L.) population on Hirta, St Kilda, is host to a erse component parasite community, but previous parasitological studies of the population have only focussed on the metazoan species. This paper reports the first epidemiological study of the protozoan species comprising Cryptosporidium parvum , Giardia duodenalis and 11 species of Eimeria in Soay sheep across 3 years of varying host population density. Prevalence and intensity of almost all species of protozoa significantly decreased with host age, with the exception of E. granulosa , which increased in prevalence with host age. The prevalence of C. parvum appeared to vary positively with host population density but that of G. duodenalis did not vary significantly with density. Most species of Eimeria showed a distinct lag in infection level following the host population crash of 2002, taking up to 2 years to decrease. Mixed Eimeria species intensity and ersity were highest in 2002, a year of low host density. Parasite ersity decreased with host age and was higher in males. There were 5 positive pair-wise associations between protozoa species in terms of prevalence. The results of this study highlight the potential for protozoal infection to shape the evolution of parasite resistance in wild host populations harbouring erse parasite species.
Publisher: No publisher found
DOI: 10.1038/NATURE18608}
Publisher: No publisher found
DOI: 10.1111/EVO.13554}
Publisher: No publisher found
Publisher: Wiley
Date: 2007
Publisher: The Royal Society
Date: 23-01-2008
Abstract: The antagonistic pleiotropy (AP) theory of ageing predicts genetically based trade-offs between investment in reproduction in early life and survival and performance in later life. Laboratory-based research has shown that such genetic trade-offs exist, but little is currently known about their prevalence in natural populations. We used random regression ‘animal model’ techniques to test the genetic basis of trade-offs between early-life fecundity (ELF) and maternal performance in late life in a wild population of red deer ( Cervus elaphus ) on the Isle of Rum, Scotland. Significant genetic variation for both ageing rates in a key maternal performance measure (offspring birth weight) and ELF was present in this population. We found some evidence for a negative genetic covariance between the rate of ageing in offspring birth weight and ELF, and also for a negative environmental covariance. Our results suggest rare support for the AP theory of ageing from a wild population.
Publisher: Wiley
Date: 08-06-2015
DOI: 10.1111/GCB.12926
Abstract: Despite extensive research on the topic, it has been difficult to reach general conclusions as to the effects of climate change on morphology in wild animals: in particular, the effects of warming temperatures have been associated with increases, decreases or stasis in body size in different populations. Here, we use a fine-scale analysis of associations between weather and offspring body size in a long-term study of a wild passerine bird, the cooperatively breeding superb fairy-wren, in south-eastern Australia to show that such variation in the direction of associations occurs even within a population. Over the past 26 years, our study population has experienced increased temperatures, increased frequency of heatwaves and reduced rainfall - but the mean body mass of chicks has not changed. Despite the apparent stasis, mass was associated with weather across the previous year, but in multiple counteracting ways. Firstly, (i) chick mass was negatively associated with extremely recent heatwaves, but there also positive associations with (ii) higher maximum temperatures and (iii) higher rainfall, both occurring in a period prior to and during the nesting period, and finally (iv) a longer-term negative association with higher maximum temperatures following the previous breeding season. Our results illustrate how a morphological trait may be affected by both short- and long-term effects of the same weather variable at multiple times of the year and that these effects may act in different directions. We also show that climate within the relevant time windows may not be changing in the same way, such that overall long-term temporal trends in body size may be minimal. Such complexity means that analytical approaches that search for a single 'best' window for one particular weather variable may miss other relevant information, and is also likely to make analyses of phenotypic plasticity and prediction of longer-term population dynamics difficult.
Publisher: University of Chicago Press
Date: 2010
DOI: 10.1086/648604
Abstract: Best linear unbiased prediction (BLUP) is a method for obtaining point estimates of a random effect in a mixed effect model. Over the past decade it has been used extensively in ecology and evolutionary biology to predict in idual breeding values and reaction norms. These predictions have been used to infer natural selection, evolutionary change, spatial-genetic patterns, in idual reaction norms, and frailties. In this article we show analytically and through simulation and ex le why BLUP often gives anticonservative and biased estimates of evolutionary and ecological parameters. Although some concerns with BLUP methodology have been voiced before, the scale and breadth of the problems have probably not been widely appreciated. Bias arises because BLUPs are often used to estimate effects that are not explicitly accounted for in the model used to make the predictions. In these cases, predicted breeding values will often say more about phenotypic patterns than the genetic patterns of interest. An additional problem is that BLUPs are point estimates of quantities that are usually known with little certainty. Failure to account for this uncertainty in subsequent tests can lead to both bias and extreme anticonservatism. We demonstrate that restricted maximum likelihood and Bayesian solutions exist for these problems and show how unbiased and powerful tests can be derived that adequately quantify uncertainty. Of particular utility is a new test for detecting evolutionary change that not only accounts for prediction error in breeding values but also accounts for drift. To illustrate the problem, we apply these tests to long-term data on the Soay sheep (Ovis aries) and the great tit (Parus major) and show that previously reported temporal trends in breeding values are not supported.
Publisher: No publisher found
Publisher: No publisher found
Publisher: Wiley
Date: 03-02-2011
DOI: 10.1111/J.1420-9101.2010.02212.X
Abstract: By determining access to limited resources, social dominance is often an important determinant of fitness. Thus, if heritable, standard theory predicts mean dominance should evolve. However, dominance is usually inferred from the tendency to win contests, and given one winner and one loser in any dyadic contest, the mean proportion won will always equal 0.5. Here, we argue that the apparent conflict between quantitative genetic theory and common sense is resolved by recognition of indirect genetic effects (IGEs). We estimate selection on, and genetic (co)variance structures for, social dominance, in a wild population of red deer Cervus elaphus, on the Scottish island of Rum. While dominance is heritable and positively correlated with lifetime fitness, contest outcomes depend as much on the genes carried by an opponent as on the genotype of a focal in idual. We show how this dependency imposes an absolute evolutionary constraint on the phenotypic mean, thus reconciling theoretical predictions with common sense. More generally, we argue that IGEs likely provide a widespread but poorly recognized source of evolutionary constraint for traits influenced by competition.
Publisher: Wiley
Date: 14-12-2010
Publisher: Wiley
Date: 2010
DOI: 10.1111/J.1365-2656.2009.01639.X
Abstract: 1. Efforts to understand the links between evolutionary and ecological dynamics hinge on our ability to measure and understand how genes influence phenotypes, fitness and population dynamics. Quantitative genetics provides a range of theoretical and empirical tools with which to achieve this when the relatedness between in iduals within a population is known. 2. A number of recent studies have used a type of mixed-effects model, known as the animal model, to estimate the genetic component of phenotypic variation using data collected in the field. Here, we provide a practical guide for ecologists interested in exploring the potential to apply this quantitative genetic method in their research. 3. We begin by outlining, in simple terms, key concepts in quantitative genetics and how an animal model estimates relevant quantitative genetic parameters, such as heritabilities or genetic correlations. 4. We then provide three detailed ex le tutorials, for implementation in a variety of software packages, for some basic applications of the animal model. We discuss several important statistical issues relating to best practice when fitting different kinds of mixed models. 5. We conclude by briefly summarizing more complex applications of the animal model, and by highlighting key pitfalls and dangers for the researcher wanting to begin using quantitative genetic tools to address ecological and evolutionary questions.
Publisher: No publisher found
Publisher: Cambridge University Press (CUP)
Date: 17-03-2010
DOI: 10.1017/S0031182010000193
Abstract: Maternal effects occur when the maternal phenotype influences that of the offspring in addition to the effects of maternal genes, and may have a considerable influence on offspring parasite resistance. These effects, and the effects of early levels of reproduction and parasite resistance, may persist into later life and even influence ageing rates. Here we analyse a 20-year longitudinal data set collected on a free-living population of Soay sheep, to investigate the associations between a suite of maternal phenotypic traits and early-life performance on measures of parasite resistance across life. Our results show that maternal effects are important in determining offspring parasite resistance, since lambs born as twins and those born to the youngest and oldest mothers show higher parasite burdens. We show that the association between parasite resistance and natal litter size persists into adulthood. We also show that age-specific changes in parasite resistance in males are associated with natal litter size, and that age-specific changes in females are influenced by early-life levels of reproduction and parasite infection. These results add to the growing evidence that conditions experienced by in iduals during development can have a profound influence on immediate and late-life performance and may even influence ageing.
Publisher: Cambridge University Press (CUP)
Date: 26-09-2014
DOI: 10.1017/S0031182014001498
Abstract: Parasite burden varies widely between in iduals within a population, and can covary with multiple aspects of in idual phenotype. Here we investigate the sources of variation in faecal strongyle eggs counts, and its association with body weight and a suite of haematological measures, in a cohort of indigenous zebu calves in Western Kenya, using relatedness matrices reconstructed from single nucleotide polymorphism (SNP) genotypes. Strongyle egg count was heritable ( h 2 = 23·9%, s.e. = 11·8%) and we also found heritability of white blood cell counts (WBC) ( h 2 = 27·6%, s.e. = 10·6%). All the traits investigated showed negative phenotypic covariances with strongyle egg count throughout the first year: high worm counts were associated with low values of WBC, red blood cell count, total serum protein and absolute eosinophil count. Furthermore, calf body weight at 1 week old was a significant predictor of strongyle EPG at 16–51 weeks, with smaller calves having a higher strongyle egg count later in life. Our results indicate a genetic basis to strongyle EPG in this population, and also reveal consistently strong negative associations between strongyle infection and other important aspects of the multivariate phenotype.
Publisher: The Royal Society
Date: 29-06-2004
Abstract: Estimating the genetic basis of quantitative traits can be tricky for wild populations in natural environments, as environmental variation frequently obscures the underlying evolutionary patterns. I review the recent application of restricted maximum–likelihood ‘animal models’ to multigenerational data from natural populations, and show how the estimation of variance components and prediction of breeding values using these methods offer a powerful means of tackling the potentially confounding effects of environmental variation, as well as generating a wealth of new areas of investigation.
Publisher: Elsevier BV
Date: 10-2002
Publisher: No publisher found
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 11-01-2006
Abstract: Epidemiological analyses indicate that the age distribution of natural cases of transmissible spongiform encephalopathies (TSEs) reflect age-related risk of infection, however, the underlying mechanisms remain poorly understood. Using a comparative approach, we tested the hypothesis that, there is a significant correlation between risk of infection for scrapie, bovine spongiform encephalopathy (BSE) and variant CJD (vCJD), and the development of lymphoid tissue in the gut. Using anatomical data and estimates of risk of infection in mathematical models (which included results from previously published studies) for sheep, cattle and humans, we calculated the Spearman's rank correlation coefficient, r s , between available measures of Peyer's patch (PP) development and the estimated risk of infection for an in idual of the corresponding age. There was a significant correlation between the measures of PP development and the estimated risk of TSE infection the two age-related distributions peaked in the same age groups. This result was obtained for each of the three host species: for sheep, surface area of ileal PP tissue vs risk of infection, r s = 0.913 ( n = 19, P 0.001), and lymphoid follicle density vs risk of infection, r s = 0.933 ( n = 19, P 0.001) for cattle, weight of PP tissue vs risk of infection, r s = 0.693 ( n = 94, P 0.001) and for humans, number of PPs vs risk of infection, r s = 0.384 ( n = 46, P = 0.008). In addition, when changes in exposure associated with BSE-contaminated meat were accounted for, the two age-related patterns for humans remained concordant: r s = 0.360 ( n = 46, P = 0.014). Our findings suggest that, for sheep, cattle and humans alike there is an association between PP development (or a correlate of PP development) and susceptibility to natural TSE infection. This association may explain changes in susceptibility with host age, and differences in the age-susceptibility relationship between host species.
Publisher: Springer Science and Business Media LLC
Date: 10-09-2016
Publisher: Springer Science and Business Media LLC
Date: 29-06-2016
DOI: 10.1038/NATURE18608
Abstract: Differences in phenological responses to climate change among species can desynchronise ecological interactions and thereby threaten ecosystem function. To assess these threats, we must quantify the relative impact of climate change on species at different trophic levels. Here, we apply a Climate Sensitivity Profile approach to 10,003 terrestrial and aquatic phenological data sets, spatially matched to temperature and precipitation data, to quantify variation in climate sensitivity. The direction, magnitude and timing of climate sensitivity varied markedly among organisms within taxonomic and trophic groups. Despite this variability, we detected systematic variation in the direction and magnitude of phenological climate sensitivity. Secondary consumers showed consistently lower climate sensitivity than other groups. We used mid-century climate change projections to estimate that the timing of phenological events could change more for primary consumers than for species in other trophic levels (6.2 versus 2.5-2.9 days earlier on average), with substantial taxonomic variation (1.1-14.8 days earlier on average).
Publisher: Academy of Management
Date: 06-2011
Publisher: Informa UK Limited
Date: 21-01-2017
Publisher: No publisher found
DOI: 10.1086/323585}
Publisher: American Psychological Association (APA)
Date: 11-2015
DOI: 10.1037/A0038888
Abstract: Performance-prove goal orientation affects performance because it drives people to try to outperform others. A proper understanding of the performance-motivating potential of performance-prove goal orientation requires, however, that we consider the question of whom people desire to outperform. In a multilevel analysis of this issue, we propose that the shared team identification of a team plays an important moderating role here, directing the performance-motivating influence of performance-prove goal orientation to either the team level or the in idual level of performance. A multilevel study of salespeople nested in teams supports this proposition, showing that performance-prove goal orientation motivates team performance more with higher shared team identification, whereas performance-prove goal orientation motivates in idual performance more with lower shared team identification. Establishing the robustness of these findings, a second study replicates them with in idual and team performance in an educational context.
Publisher: No publisher found
Publisher: Wiley
Date: 31-08-2011
DOI: 10.1002/JOB.779
Publisher: No publisher found
Publisher: Wiley
Date: 07-2018
DOI: 10.1111/EVO.13496
Publisher: Wiley
Date: 02-11-2010
DOI: 10.1111/J.1558-5646.2010.01161.X
Abstract: In a seasonal environment, there are multiple aspects of timing, or phenology, that contribute to an in idual's fitness. Several studies have shown a genetic basis to variation between in iduals in breeding time, but we know little about the heritability of other phenological traits in wild populations. Furthermore, the presence of genetic correlations between phenological variables could act to constrain or promote any response to selection, but less is known of the multivariate genetic relationships underlying phenological traits in the wild. Here, we use data from a wild population of red deer on the Isle of Rum, Scotland, to investigate covariances between eight phenological traits. Variation was characterized at the level of the phenotype, genotype, and year, and traits measured in different sexes enabled us to test for cross-sex genetic correlations. Phenotypic correlations were broadly strong and positive, as were correlations between traits expressed in the same year. We found evidence of significant additive genetic variation in five of the eight phenological traits studied. However there was little evidence of genetic correlations between traits, implying that much of the observed phenotypic correlation was environmentally induced. Our results suggest that different phenological traits may be free to move along independent evolutionary trajectories.
Publisher: Springer Science and Business Media LLC
Date: 04-03-2021
Publisher: No publisher found
DOI: 10.1086/603615}
Publisher: No publisher found
Publisher: SAGE Publications
Date: 09-07-2016
Abstract: This literature review focused on the experience, care, and service requirements of people with younger onset dementia. Systematic searches of 10 relevant bibliographic databases and a rigorous examination of the literature from nonacademic sources were undertaken. Searches identified 304 articles assessed for relevance and level of evidence, of which 74% were academic literature. The review identified the need for (1) more timely and accurate diagnosis and increased support immediately following diagnosis (2) more in idually tailored services addressing life cycle issues (3) examination of the service needs of those living alone (4) more systematic evaluation of services and programs (5) further examination of service utilization, costs of illness, and cost effectiveness and (6) current Australian clinical surveys to estimate prevalence, incidence, and survival rates. Although previous research has identified important service issues, there is a need for further studies with stronger research designs and consideration of the control of potentially confounding factors.
Publisher: No publisher found
Publisher: Wiley
Date: 07-06-2018
DOI: 10.1111/JEB.13292
Abstract: Parental effects on offspring performance have been attributed to many factors such as parental age, size and condition. However, we know little about how these different parental characteristics interact to determine parental effects, or the extent to which their effect on offspring depends on either the sex of the parent or that of the offspring. Here we experimentally tested for effects of variation in parents' early diet and inbreeding levels, as well as effects of parental age, and for potential interactive effects of these three factors on key aspects of offspring development in the mosquitofish (Gambusia holbrooki). Older mothers produced offspring that were significantly smaller at birth. This negative effect of maternal age on offspring size was still evident at maturation as older mothers had smaller daughters, but not smaller sons. The daughters of older mothers did, however, reach maturity sooner. Paternal age did not affect offspring body size, but it had a complex effect on their sons' relative genital size. When initially raised on a food-restricted diet, older fathers sired sons with relatively smaller genitalia, but when fathers were initially raised on a control diet their sons had relatively larger genitalia. The inbreeding status of mothers and fathers had no significant effects on any of the measured offspring traits. Our results indicate that the manifestation of parental effects can be complex. It can vary with both parent and offspring sex can change over an offspring's life and is sometimes evident as an interaction between different parental traits. Understanding this complexity will be important to predict the role of parental effects in adaptation.
Publisher: University of Chicago Press
Date: 12-2005
DOI: 10.1086/497441
Abstract: Body size is an important determinant of fitness in many organisms. While size will typically change over the lifetime of an in idual, heritable components of phenotypic variance may also show ontogenetic variation. We estimated genetic (additive and maternal) and environmental covariance structures for a size trait (June weight) measured over the first 5 years of life in a natural population of bighorn sheep Ovis canadensis. We also assessed the utility of random regression models for estimating these structures. Additive genetic variance was found for June weight, with heritability increasing over ontogeny because of declining environmental variance. This pattern, mirrored at the phenotypic level, likely reflects viability selection acting on early size traits. Maternal genetic effects were significant at ages 0 and 1, having important evolutionary implications for early weight, but declined with age being negligible by age 2. Strong positive genetic correlations between age-specific traits suggest that selection on June weight at any age will likely induce positively correlated responses across ontogeny. Random regression modeling yielded similar results to traditional methods. However, by facilitating more efficient data use where phenotypic s ling is incomplete, random regression should allow better estimation of genetic (co)variances for size and growth traits in natural populations.
Publisher: Wiley
Date: 25-01-2016
DOI: 10.1002/ECE3.1945
Publisher: Microbiology Society
Date: 04-2005
Abstract: Five different sheep flocks with natural outbreaks of scrapie were examined to determine associations between in idual performance (lifetime breeding success, litter size and survival) and scrapie infection or PrP genotype. Despite different breed composition and forces of infection, consistent patterns were found among the flocks. Regardless of the flock, scrapie-infected sheep produced on average 34 % fewer offspring than non-scrapie-infected sheep. The effect of scrapie on lifetime breeding success appears to be a function of lifespan as opposed to fecundity. Analysis of litter size revealed no overall or genotype differences among the five sheep flocks. Survival, however, depends on the in idual's scrapie status (infected or not) and its PrP genotype. Susceptible genotypes appear to perform less well in lifetime breeding success and life expectancy even if they are never affected with clinical scrapie. One possible explanation for these results is the effect of pre-clinical scrapie. Additional evidence supporting this hypothesis is discussed.
Publisher: No publisher found
Publisher: Springer Science and Business Media LLC
Date: 2001
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-03-2017
Abstract: Climate change will fundamentally alter many aspects of the natural world. To understand how species may adapt to this change, we must understand which aspects of the changing climate exert the most powerful selective forces. Siepielski et al. looked at studies of selection across species and regions and found that, across biomes, the strongest sources of selection were precipitation and transpiration changes. Importantly, local and regional climate change explained patterns of selection much more than did global change. Science , this issue p. 959
Publisher: Wiley
Date: 06-2007
Publisher: Oxford University Press (OUP)
Date: 05-04-2021
Abstract: In cooperatively breeding species, the presence of male helpers in a group often reduces the breeding female’s fidelity to her social partner, possibly because there is more than one potential sire in the group. Using a long-term study of cooperatively breeding superb fairy-wrens (Malurus cyaneus) and records of paternity in 1936 broods, we show that the effect of helpers on rates of extrapair paternity varied according to the helpers’ relatedness to the breeding female. The presence of unrelated male helpers in a group increased average rates of extrapair paternity, from 57% for groups with no unrelated helpers, to 74% with one unrelated helper, to 86% with 2+ unrelated helpers. However, this increase was due in equal part to helpers within the group and males in other groups achieving increased paternity. In contrast, helpers who were sons of the breeding female did not gain paternity, nor did they affect the level of extra-group paternity (which occurred at rates of 60%, 58%, 61% in the presence of 0, 1, 2+ helper sons, respectively). There was no evidence of effects of helpers’ relatedness to the female on nest productivity or nestling performance. Because the presence of helpers per se did not elevate extrapair reproduction rates, our results undermine the “constrained female hypothesis” explanation for an increase in extrapair paternity with helper number in cooperative breeders. However, they indicate that dominant males are disadvantaged by breeding in “cooperative” groups. The reasons why the presence of unrelated helpers, but not of helper-sons, results in higher rates of extra-group reproduction are not clear.
Publisher: No publisher found
DOI: 10.1086/664686}
Publisher: The Royal Society
Date: 09-2016
Abstract: Costs of reproduction are expected to be ubiquitous in wild animal populations and understanding the drivers of variation in these costs is an important aspect of life-history evolution theory. We use a 43 year dataset from a wild population of red deer to examine the relative importance of two factors that influence the costs of reproduction to mothers, and to test whether these costs vary with changing ecological conditions. Like previous studies, our analyses indicate fitness costs of lactation: mothers whose calves survived the summer subsequently showed lower survival and fecundity than those whose calves died soon after birth, accounting for 5% and 14% of the variation in mothers' survival and fecundity, respectively. The production of a male calf depressed maternal survival and fecundity more than production of a female, but accounted for less than 1% of the variation in either fitness component. There was no evidence for any change in the effect of calf survival or sex with increasing population density.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Loeske E.B. Kruuk.