ORCID Profile
0000-0002-8091-1044
Current Organisation
Université de Sherbrooke
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Publisher: Wiley
Date: 28-04-2005
Publisher: The Royal Society
Date: 27-12-2010
Abstract: The pace-of-life syndrome (POLS) hypothesis specifies that closely related species or populations experiencing different ecological conditions should differ in a suite of metabolic, hormonal and immunity traits that have coevolved with the life-history particularities related to these conditions. Surprisingly, two important dimensions of the POLS concept have been neglected: (i) despite increasing evidence for numerous connections between behavioural, physiological and life-history traits, behaviours have rarely been considered in the POLS yet (ii) the POLS could easily be applied to the study of covariation among traits between in iduals within a population. In this paper, we propose that consistent behavioural differences among in iduals, or personality, covary with life history and physiological differences at the within-population, interpopulation and interspecific levels. We discuss how the POLS provides a heuristic framework in which personality studies can be integrated to address how variation in personality traits is maintained within populations.
Publisher: Wiley
Date: 18-05-2011
Publisher: Wiley
Date: 2008
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: Springer Science and Business Media LLC
Date: 11-11-2011
DOI: 10.1007/S00360-011-0628-5
Abstract: In response to handling or other acute stressors, most mammals, including humans, experience a temporary rise in body temperature (T(b)). Although this stress-induced rise in T(b) has been extensively studied on model organisms under controlled environments, in idual variation in this interesting phenomenon has not been examined in the field. We investigated the stress-induced rise in T(b) in free-ranging eastern chipmunks (Tamias striatus) to determine first if it is repeatable. We predicted that the stress-induced rise in T(b) should be positively correlated to factors affecting heat production and heat dissipation, including ambient temperature (T(a)), body mass (M(b)), and field metabolic rate (FMR). Over two summers, we recorded both T(b) within the first minute of handling time (T(b1)) and after 5 min of handling time (T(b5)) 294 times on 140 in iduals. The mean ∆T(b) (T(b5) - T(b1)) during this short interval was 0.30 ± 0.02°C, confirming that the stress-induced rise in T(b) occurs in chipmunks. Consistent differences among in iduals accounted for 40% of the total variation in ∆T(b) (i.e. the stress-induced rise in T(b) is significantly repeatable). We also found that the stress-induced rise in T(b) was positively correlated to T(a), M(b), and mass-adjusted FMR. These results confirm that in iduals consistently differ in their expression of the stress-induced rise in T(b) and that the extent of its expression is affected by factors related to heat production and dissipation. We highlight some research constraints and opportunities related to the integration of this laboratory paradigm into physiological and evolutionary ecology.
Publisher: Springer Science and Business Media LLC
Date: 31-01-2015
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: Canadian Science Publishing
Date: 03-2012
DOI: 10.1139/Z2012-008
Abstract: Given the ubiquity and evolutionary importance of parasites, their effect on the energy budget of mammals remains surprisingly unclear. The eastern chipmunk ( Tamias striatus (L., 1758)) is a burrowing rodent that is commonly infected by cuterebrid bot fly ( Cuterebra emasculator Fitch, 1856) larvae. We measured resting metabolic rate (RMR) and cold-induced Vo 2 -max (under heliox atmosphere) in 20 free-ranging in iduals, of which 4 in iduals were infected by one or two larva. We found that RMR was significantly higher in chipmunks infected by bot fly larvae (mean ± SE = 0.88 ± 0.05 W) than in uninfected in iduals (0.74 ± 0.02 W). In contrast, Vo 2 -max was significantly lower in chipmunks infected by bot fly larvae (4.96 ± 0.70 W) than in uninfected in iduals (6.37 ± 0.16 W). Consequently, the aerobic scope (ratio of Vo 2 -max to RMR) was negatively correlated with the number of bot fly larvae (infected in iduals = 5.74 ± 1.03 W noninfected in iduals = 8.67 ± 0.26 W). Finally, after accounting for the effects of body mass and bot fly parasitism on RMR and Vo 2 -max, there was no correlation between the two variables among in iduals within our population. In addition to providing the first estimate of Vo 2 -max in T. striatus, these results offer additional evidence that bot fly parasitism has significant impacts on the metabolic ecology of this host species.
Publisher: The Company of Biologists
Date: 2013
DOI: 10.1242/JEB.076794
Abstract: Several empirical studies have shown that variation in daily energy expenditure (DEE) and resting metabolic rate (RMR) is influenced by environmental and in idual factors, but whether these shared influences are responsible for, or independent of, relationships between DEE and RMR remains unknown. The objectives of this study were to i) simultaneously evaluate the effects of environmental and in idual variables on DEE and RMR in free-ranging eastern chipmunks (Tamias striatus) and ii) quantify the correlation between DEE and RMR before and after controlling for common sources of variation. We found that the influence of in idual factors on DEE and RMR are most often shared, whereas the influence of environmental factors tends to be distinct. Both raw and mass-adjusted DEE and RMR were significantly correlated, but this correlation vanished after accounting for the shared effect of reproduction on both traits. However, within reproductive in iduals, DEE and RMR remained positively correlated after accounting for all other significant covariates. The ratio of DEE to RMR was significantly higher during reproduction than at other times of the year and was negatively correlated with ambient temperature. DEE and RMR appear to be inherently correlated during reproduction, but this correlation does not persist during other, less energy-demanding periods of the annual cycle.
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: Elsevier BV
Date: 10-2015
DOI: 10.1016/J.TREE.2015.07.006
Abstract: The recent trend for journals to require open access to primary data included in publications has been embraced by many biologists, but has caused apprehension amongst researchers engaged in long-term ecological and evolutionary studies. A worldwide survey of 73 principal investigators (Pls) with long-term studies revealed positive attitudes towards sharing data with the agreement or involvement of the PI, and 93% of PIs have historically shared data. Only 8% were in favor of uncontrolled, open access to primary data while 63% expressed serious concern. We present here their viewpoint on an issue that can have non-trivial scientific consequences. We discuss potential costs of public data archiving and provide possible solutions to meet the needs of journals and researchers.
Publisher: Wiley
Date: 2007
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: Wiley
Date: 23-06-2011
DOI: 10.1111/J.1420-9101.2011.02344.X
Abstract: According to the 'pace-of-life' syndrome hypothesis, differences in resting metabolic rate (RMR) should be genetically associated with exploratory behaviour. A large number of studies reported significant heritability for both RMR and exploratory behaviour, but the genetic correlation between the two has yet to be documented. We used a quantitative genetic approach to decompose the phenotypic (co)variance of several metabolic and behavioural measures into components of additive genetic, common environment and permanent environment variance in captive deer mice. We found significant additive genetic variance for two mass-independent metabolic measures (RMR and the average metabolic rate throughout the respirometry run) and two behavioural measures (time spent in centre and distance moved in a novel environment). We also detected positive additive genetic correlation between mass-independent RMR and distance moved (r(A) = 0.78 ± 0.23). Our results suggest that RMR and exploratory behaviour are functionally integrated traits in deer mice, providing empirical support for one of the connections within the pace-of-life syndrome hypothesis.
Publisher: Springer Science and Business Media LLC
Date: 13-06-2012
DOI: 10.1007/S00442-012-2385-X
Abstract: The growth/survival trade-off is a fundamental aspect of life-history evolution that is often explained by the direct energetic requirement for growth that cannot be allocated into maintenance. However, there is currently no empirical consensus on whether fast-growing in iduals have higher resting metabolic rates at thermoneutrality (RMRt) than slow growers. Moreover, the link between growth rate and daily energy expenditure (DEE) has never been tested in a wild endotherm. We assessed the energetic and survival costs of growth in juvenile eastern chipmunks (Tamias striatus) during a year of low food abundance by quantifying post-emergent growth rate (n = 88), RMRt (n = 66), DEE (n = 20), and overwinter survival. Both RMRt and DEE were significantly and positively related to growth rate. The effect size was stronger for DEE than RMRt, suggesting that the energy cost of growth in wild animals is more likely to be related to the maintenance of a higher foraging rate (included in DEE) than to tissue accretion (included in RMRt). Fast growers were significantly less likely to survive the following winter compared to slow growers. Juveniles with high or low RMRt were less likely to survive winter than juveniles with intermediate RMRt. In contrast, DEE was unrelated to survival. In addition, botfly parasitism simultaneously decreased growth rate and survival, suggesting that the energetic budget of juveniles was restricted by the simultaneous costs of growth and parasitism. Although the biology of the species (seed-storing hibernator) and the context of our study (constraining environmental conditions) were ideally combined to reveal a direct relationship between current use of energy and future availability, it remains unclear whether the energetic cost of growth was directly responsible for reduced survival.
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Dany Garant.