ORCID Profile
0000-0002-5786-6951
Current Organisation
University of New South Wales
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Evolutionary Biology | Life Histories (Incl. Population Ecology) | Life Histories | Ecology And Evolution Not Elsewhere Classified | Genetics | Quantitative Genetics | Biological Adaptation | Animal Structure and Function | Ecology | Invertebrate Biology | Genetic Development (Incl. Sex Determination) | Marine And Estuarine Ecology (Incl. Marine Ichthyology) | Sociobiology And Behavioural Ecology |
ANZSRC Socio-Economic Objective (SEO)
Expanding Knowledge in the Biological Sciences | Biological sciences | Inherited diseases (incl. gene therapy) | Integrated (ecosystem) assessment and management | Integrated (ecosystem) assessment and management | Control of pests and exotic species | Environmental health | Health related to ageing | Global climate change adaptation measures
Related Links
Publications
The nutritional geometry of parental effects: maternal and paternal macronutrient consumption and offspring phenotype in a neriid fly
Publisher: Wiley
Date: 22-02-2016
Dietary restriction fails to extend life in stressful environments
Publisher: Wiley
Date: 23-06-2023
Abstract: Moderate dietary restriction often prolongs life in laboratory animals, and this response has been interpreted as an adaptive strategy that promotes survival during famine. However, dietary restriction can also increase frailty, and it therefore remains unclear whether restricted diets prolong life under stressful conditions like those experienced by wild animals. We manipulated adult dietary protein of Drosophila melanogaster across a gradient of ambient temperature, and examined effects on survival. To test for trade‐offs, we also quantified reproduction, and performance of F1, F2 and F3 descendants. We found that protein restriction increased longevity of one or both sexes at benign ambient temperatures (25°C and 27°C), but failed to extend longevity of flies maintained in cold (21°C and 23°C) or hot (29°C) conditions. Instead, in females, protein restriction resulted in strongly elevated mortality at cold temperatures. Protein restriction also generally reduced reproductive performance, and did not consistently enhance performance of F1, F2 or F3 descendants. Taken together, our results challenge the long‐held idea that extended longevity of diet‐restricted laboratory animals represents an adaptive survival strategy in natural populations. Our findings suggest instead that this response is an artefact of benign laboratory conditions, and that DR‐induced life extension might not be achieved in the more stressful conditions experienced in the wild. Read the free Plain Language Summary for this article on the Journal blog.
Rethinking heredity, again
Publisher: Elsevier BV
Date: 06-2012
DOI: 10.1016/J.TREE.2012.02.003
Abstract: The refutation of 'soft' inheritance and establishment of Mendelian genetics as the exclusive model of heredity is widely portrayed as an iconic success story of scientific progress. Yet, we are witnessing a re-emergence of debate on the role of soft inheritance in heredity and evolution. I argue that this reversal reflects not only the weight of new evidence but also an important conceptual change. I show that the concept of soft inheritance rejected by 20th-century genetics differs fundamentally from the current concept of 'nongenetic inheritance'. Moreover, whereas it has long been assumed that heredity is mediated by a single, universal mechanism, a pluralistic model of heredity is now emerging, based on a recognition of multiple, parallel mechanisms of inheritance.
Sexual selection and conflict as engines of ecological diversification
Publisher: University of Chicago Press
Date: 03-2011
DOI: 10.1086/662665
Abstract: Ecological ersification presents an enduring puzzle: how do novel ecological strategies evolve in organisms that are already adapted to their ecological niche? Most attempts to answer this question posit a primary role for genetic drift, which could carry populations through or around fitness "valleys" representing maladaptive intermediate phenotypes between alternative niches. Sexual selection and conflict are thought to play an ancillary role by initiating reproductive isolation and thereby facilitating ergence in ecological traits through genetic drift or local adaptation. Here, I synthesize theory and evidence suggesting that sexual selection and conflict could play a more central role in the evolution and ersification of ecological strategies through the co-optation of sexual traits for viability-related functions. This hypothesis rests on three main premises, all of which are supported by theory and consistent with the available evidence. First, sexual selection and conflict often act at cross-purposes to viability selection, thereby displacing populations from the local viability optimum. Second, sexual traits can serve as preadaptations for novel viability-related functions. Third, ancestrally sex-limited sexual traits can be transferred between sexes. Consequently, by allowing populations to explore a broad phenotypic space around the current viability optimum, sexual selection and conflict could act as powerful drivers of ecological adaptation and ersification.
Sex-biased transcriptome divergence along a latitudinal gradient
Publisher: Wiley
Date: 08-02-2017
DOI: 10.1111/MEC.14015
Abstract: Sex-dependent gene expression is likely an important genomic mechanism that allows sex-specific adaptation to environmental changes. Among Drosophila species, sex-biased genes display remarkably consistent evolutionary patterns male-biased genes evolve faster than unbiased genes in both coding sequence and expression level, suggesting sex differences in selection through time. However, comparatively little is known of the evolutionary process shaping sex-biased expression within species. Latitudinal clines offer an opportunity to examine how changes in key ecological parameters also influence sex-specific selection and the evolution of sex-biased gene expression. We assayed male and female gene expression in Drosophila serrata along a latitudinal gradient in eastern Australia spanning most of its endemic distribution. Analysis of 11 631 genes across eight populations revealed strong sex differences in the frequency, mode and strength of ergence. Divergence was far stronger in males than females and while latitudinal clines were evident in both sexes, male ergence was often population specific, suggesting responses to localized selection pressures that do not covary predictably with latitude. While ergence was enriched for male-biased genes, there was no overrepresentation of X-linked genes in males. By contrast, X-linked ergence was elevated in females, especially for female-biased genes. Many genes that erged in D. serrata have homologs also showing latitudinal ergence in Drosophila simulans and Drosophila melanogaster on other continents, likely indicating parallel adaptation in these distantly related species. Our results suggest that sex differences in selection play an important role in shaping the evolution of gene expression over macro- and micro-ecological spatial scales.
Revisiting telegony: Offspring inherit an acquired characteristic of their mother's previous mate
Publisher: Wiley
Date: 30-09-2014
DOI: 10.1111/ELE.12373
Effects of larval diet quality on the growth and development of immature stages of Telostylinus angusticollis (Diptera : Neriidae)
Publisher: CSIRO Publishing
Date: 2018
DOI: 10.1071/ZO19021
Abstract: Nutrient abundance during development has profound effects on adult morphology, life history and behaviour in many insects, but effects of nutrition on juvenile development are less well known. We investigated how larval diet quality affects patterns of growth, development and survival of larvae and pupae in the neriid fly Telostylinus angusticollis (Enderlein). We reared flies on two larval diets varying in nutrient concentration (‘rich’ versus ‘poor’) that have been shown previously to affect a wide range of adult traits in this species. We found that nutrient concentration affected larval growth trajectories, with in iduals reared on the rich diet exhibiting greatly accelerated growth and reaching a larger body size. By contrast, we found no evidence that diet affected timing of development at the pupal stage, suggesting that developmental constraints may prevent variation in pupal development rate. Although overall mortality during the immature stages was not affected by larval diet, we found some evidence that in iduals reared on a poor diet might experience higher larval mortality, whereas in iduals reared on a rich diet might experience higher mortality during emergence from the puparium. Our results enhance understanding of the effects of nutrition on growth, development, and life history.
Sexual conflict, life span, and aging
Publisher: Cold Spring Harbor Laboratory
Date: 23-06-2014
Condition dependence of developmental stability in the sexually dimorphic fly Telostylinus angusticollis (Diptera: Neriidae)
Publisher: Wiley
Date: 13-03-2009
DOI: 10.1111/J.1420-9101.2009.01686.X
Abstract: Developmental stability is widely regarded as a condition-dependent trait, but its relation to genotype and environment, and extent of developmental integration, remain contentious. In Telostylinus angusticollis, the dorsocentral bristles exhibit striking variation in developmental stability, manifested as fluctuating asymmetry (FA) in bristle position ('positional FA') and failure to develop some bristles ('bristle loss'), in natural and laboratory populations. To determine whether this variation reflects condition, I tested for effects of genotype and environment (larval diet quality), and examined covariation with condition-dependent traits. Positional FA was not affected by genotype or environment. However, positional FA covaried negatively with secondary sexual trait expression in males, and with sexual dimorphism in body shape, but covaried positively with body size in females. Bristle loss reflected both genotype and larval diet. Flies reared on poor-quality diet exhibited a similar rate of bristle loss as wild flies. Both positional FA and bristle loss were greater in males. These results suggest that the relation between developmental stability and condition is complex and sex dependent.
Seminal Fluid and Mate Choice: New Predictions
Publisher: Elsevier BV
Date: 04-2016
DOI: 10.1016/J.TREE.2016.02.004
Abstract: Recent evidence shows that seminal fluid can affect females and offspring independently of fertilisation in species lacking conventional 'nuptial gifts'. We argue that a hypothesis from paternal investment systems - that selection can favour changing female preferences that maximise both sperm-borne and seminal fluid-borne benefits - could therefore apply much more broadly.
Adult dietary protein has age- and context-dependent effects on male post-copulatory performance
Publisher: Wiley
Date: 12-05-2017
DOI: 10.1111/JEB.13087
Abstract: The highly conserved effect of dietary protein restriction on lifespan and ageing is observed in both sexes and across a vast range of taxa. This extension of lifespan is frequently accompanied by a reduction in female fecundity, and it has been hypothesized that in iduals may reallocate resources away from reproduction and into somatic maintenance. However, effects of dietary protein restriction on male reproduction are less consistent, suggesting that these effects may depend on other environmental parameters. Using the neriid fly, Telostylinus angusticollis, we examined age-specific effects of adult dietary protein restriction on male post-copulatory reproductive performance (fecundity and offspring viability). To explore the context dependence of these effects, we simultaneously manipulated male larval diet and adult mating history. We found that protein-restricted males sired less viable offspring at young ages, but offspring viability increased with paternal age and eventually exceeded that of fully fed males. The number of eggs laid by females was not affected by male dietary protein, whereas egg hatching success was subject to a complex interaction of male adult diet, age, larval diet and mating history. These findings suggest that effects of protein restriction on male reproduction are highly context dependent and cannot be explained by a simple reallocation of resources from reproduction to somatic maintenance. Rather, these effects appear to involve changes in the scheduling of male reproductive investment with age.
Comparing ageing and the effects of diet supplementation in wild vs. captive antler flies, Protopiophila litigata
Publisher: Wiley
Date: 26-08-2019
Abstract: Few studies have simultaneously compared ageing within genetically similar populations in both laboratory and natural environments. Such comparisons are important for interpreting laboratory studies, because factors such as diet could affect ageing in environment-dependent ways. Using a natural population of antler flies (Protopiophila litigata), we conducted separate factorial experiments in 2012 and 2013 that compared age-specific male survival and mating success in laboratory cages versus a natural field environment while supplementing their diets with protein or sugar. We found consistent and substantial increases in both survival and mating rates in the laboratory compared to the field, but remarkably, despite these large differences actuarial ageing was only higher in the laboratory than in the field in 2012 and similar in the two environments in 2013. In both years, there was no difference between environments in reproductive ageing. We found that males fed protein had a higher mortality rate than males fed sugar (strong and low support in 2012 and 2013, respectively). In contrast, diet did not strongly impact average mating rates, actuarial ageing or reproductive ageing in either experiment. Our results provide the first evidence that the negative effect of protein on life span reported in many laboratory studies can also occur in wild populations, although perhaps less consistently. They also highlight how laboratory environments can influence life-history traits and suggest caution when extrapolating from the laboratory to the field.
Reproductive allocation and reproductive ecology of seven species of Diptera
Publisher: Wiley
Date: 11-1999
Intralocus Sexual Conflict Can Drive the Evolution of Genomic Imprinting
Publisher: Oxford University Press (OUP)
Date: 08-2004
DOI: 10.1534/GENETICS.103.026211
Abstract: Genomic imprinting is a phenomenon whereby the expression of an allele differs depending upon its parent of origin. There is an increasing number of ex les of this form of epigenetic inheritance across a wide range of taxa, and imprinting errors have also been implicated in several human diseases. Various hypotheses have been put forward to explain the evolution of genomic imprinting, but there is not yet a widely accepted general hypothesis for the variety of imprinting patterns observed. Here a new evolutionary hypothesis, based on intralocus sexual conflict, is proposed. This hypothesis provides a potential explanation for much of the currently available empirical data, and it also makes new predictions about patterns of genomic imprinting that are expected to evolve but that have not, as of yet, been looked for in nature. This theory also provides a potential mechanism for the resolution of intralocus sexual conflict in sexually selected traits and a novel pathway for the evolution of sexual dimorphism.
The fitness effects of delayed switching to sex in a facultatively asexual insect
Publisher: Wiley
Date: 06-02-2018
DOI: 10.1002/ECE3.3895
A Unified Approach to the Evolutionary Consequences of Genetic and Nongenetic Inheritance
Publisher: University of Chicago Press
Date: 08-2011
DOI: 10.1086/660911
Abstract: Inheritance-the influence of ancestors on the phenotypes of their descendants-translates natural selection into evolutionary change. For the past century, inheritance has been conceptualized almost exclusively as the transmission of DNA sequence variation from parents to offspring in accordance with Mendelian rules, but advances in cell and developmental biology have now revealed a rich array of inheritance mechanisms. This empirical evidence calls for a unified conception of inheritance that combines genetic and nongenetic mechanisms and encompasses the known range of transgenerational effects, including the transmission of genetic and epigenetic variation, the transmission of plastic phenotypes (acquired traits), and the effects of parental environment and genotype on offspring phenotype. We propose a unified theoretical framework based on the Price equation that can be used to model evolution under an expanded inheritance concept that combines the effects of genetic and nongenetic inheritance. To illustrate the utility and generality of this framework, we show how it can be applied to a variety of scenarios, including nontransmissible environmental noise, maternal effects, indirect genetic effects, transgenerational epigenetic inheritance, RNA-mediated inheritance, and cultural inheritance.
Rapid and costly ageing in wild male flies
Publisher: Springer Science and Business Media LLC
Date: 11-2002
DOI: 10.1038/420377A
Evolution in Four Dimensions, by Eva Jablonka and Marion Lamb. MIT Press, Cambridge, Mass. USA
Publisher: University of Chicago Press
Date: 03-2017
DOI: 10.1086/690868
Sex-specific fitness effects of nutrient intake on reproduction and lifespan
Publisher: Elsevier BV
Date: 07-2008
DOI: 10.1016/J.CUB.2008.06.059
Abstract: Diet affects both lifespan and reproduction [1-9], leading to the prediction that the contrasting reproductive strategies of the sexes should result in sex-specific effects of nutrition on fitness and longevity [6, 10] and favor different patterns of nutrient intake in males and females. However, males and females share most of their genome and intralocus sexual conflict may prevent sex-specific diet optimization. We show that both male and female longevity were maximized on a high-carbohydrate low-protein diet in field crickets Teleogryllus commodus, but male and female lifetime reproductive performances were maximized in markedly different parts of the nutrient intake landscape. Given a choice, crickets exhibited sex-specific dietary preference in the direction that increases reproductive performance, but this sexual dimorphism in preference was incomplete, with both sexes displaced from the optimum diet for lifetime reproduction. Sexes are, therefore, constrained in their ability to reach their sex-specific dietary optima by the shared biology of diet choice. Our data suggest that sex-specific selection has thus far failed fully to resolve intralocus sexual conflict over diet optimization. Such conflict may be an important factor linking nutrition and reproduction to lifespan and aging.
SEX DIFFERENCES, SEXUAL SELECTION, AND AGEING: AN EXPERIMENTAL EVOLUTION APPROACH
Publisher: Wiley
Date: 10-2009
DOI: 10.1111/J.1558-5646.2009.00750.X
Abstract: Life-history (LH) theory predicts that selection will optimize the trade-off between reproduction and somatic maintenance. Reproductive ageing and finite life span are direct consequences of such optimization. Sexual selection and conflict profoundly affect the reproductive strategies of the sexes and thus can play an important role in the evolution of life span and ageing. In theory, sexual selection can favor the evolution of either faster or slower ageing, but the evidence is equivocal. We used a novel selection experiment to investigate the potential of sexual selection to influence the adaptive evolution of age-specific LH traits. We selected replicate populations of the seed beetle Callosobruchus maculatus for age at reproduction ("Young" and "Old") either with or without sexual selection. We found that LH selection resulted in the evolution of age-specific reproduction and mortality but these changes were largely unaffected by sexual selection. Sexual selection depressed net reproductive performance and failed to promote adaptation. Nonetheless, the evolution of several traits differed between males and females. These data challenge the importance of current sexual selection in promoting rapid adaptation to environmental change but support the hypothesis that sex differences in LH-a historical signature of sexual selection-are key in shaping trait responses to novel selection.
Reproductive ageing and sexual selection on male body size in a wild population of antler flies (Protopiophila litigata)
Publisher: Wiley
Date: 25-08-2005
DOI: 10.1111/J.1420-9101.2005.00957.X
Abstract: Little is known about the importance of trade-offs between ageing and other life history traits, or the effects of ageing on sexual selection, particularly in wild populations suffering high extrinsic mortality rates. Life history theory suggests that trade-offs between reproduction and somatic maintenance may constrain in iduals with higher initial reproductive rates to deteriorate more rapidly, resulting in reduced sexual selection strength. However, this trade-off may be masked by increased condition dependence of reproductive effort in older in iduals. We tested for this trade-off in males in a wild population of antler flies (Protopiophila litigata). High mating rate was associated with reduced longevity, as a result of increased short-term mortality risk or accelerated ageing in traits affecting viability. In contrast, large body size was associated with accelerated ageing in traits affecting mating success, resulting in reduced sexual selection for large body size. Thus, ageing can affect sexual selection and evolution in wild populations.
Convergent evolution of sexual shape dimorphism in diptera
Publisher: Wiley
Date: 2006
DOI: 10.1002/JMOR.10426
Abstract: Several patterns of sexual shape dimorphism, such as male body elongation, eye stalks, or extensions of the exoskeleton, have evolved repeatedly in the true flies (Diptera). Although these dimorphisms may have evolved in response to sexual selection on male body shape, conserved genetic factors may have contributed to this convergent evolution, resulting in stronger phenotypic convergence than might be expected from functional requirements alone. I compared phenotypic variation in body shape in two distantly related species exhibiting sexually dimorphic body elongation: Prochyliza xanthostoma (Piophilidae) and Telostylinus angusticollis (Neriidae). Although sexual selection appears to act differently on male body shape in these species, they exhibited strikingly similar patterns of sexual dimorphism. Likewise, patterns of within-sex shape variation were similar in the two species, particularly in males: relative elongation of the male head capsule, antenna, and legs was associated with reduced head capsule width and wing length, but was nearly independent of variation in thorax length. However, the two species presented contrasting patterns of static allometry: male sexual traits exhibited elevated allometric slopes in T. angusticollis, but not in P. xanthostoma. These results suggest that a shared pattern of covariation among traits may have channeled the evolution of sexually dimorphic body elongation in these species. Nonetheless, static allometries may have been shaped by species-specific selection pressures or genetic architectures.
Why do male antler flies (protopiophila litigata) fight? the role of male combat in the structure of mating aggregations on moose antlers
Publisher: Informa UK Limited
Date: 07-1999
Epigenetic paternal effects as costly, condition-dependent traits
Publisher: Springer Science and Business Media LLC
Date: 14-06-2018
Sexually but not parthenogenetically produced females benefit from mating in a stick insect
Publisher: Wiley
Date: 08-06-2022
Abstract: In facultatively parthenogenetic populations, the prevalence of sexual reproduction depends on whether females mate and therefore produce sons and daughters or avoid mating and produce daughters only. The relative advantage of mating in such species may depend on a female's own reproductive origin (i.e. development from a fertilised or unfertilised egg) if parthenogenesis reduces heterozygosity similar to sexual inbreeding, or if it inhibits mating, sperm storage or fertilisation. But effects of reproductive origin on development and performance are poorly understood. Using the facultatively parthenogenetic stick insect, Extatosoma tiaratum , we quantified morphology, mating probability, and reproductive success in mated versus unmated females of sexual versus automictic (parthenogenetic) origin. We found strong evidence that increased homozygosity negatively impacted some traits in parthenogenetically produced females: compared to sexually produced females, parthenogenetically produced females were smaller and more prone to deformities in vestigial wings, but not more prone to fluctuating asymmetry in their legs. Parthenogenetically produced females received fewer mating attempts and avoided mating more often than sexually produced females. Yet, contrary to the expectation that sex should rescue parthenogenetic lineages from the detrimental effects of increased homozygosity, parthenogenetically produced females gained no net reproductive benefit from mating, suggesting that physiological constraints limit fitness returns of sexual reproduction for these females. Our findings indicate that advantages of mating in this species depend on female reproductive origin. These results could help to explain spatial distributions of sex in facultatively parthenogenetic animals and evolutionary transitions to obligate asexuality. Read the free Plain Language Summary for this article on the Journal blog.
Sperm depletion in relation to developmental nutrition and genotype in Drosophila melanogaster
Publisher: Wiley
Date: 19-10-2021
DOI: 10.1111/EVO.14373
Nongenetic inheritance and the evolution of costly female preference
Publisher: Wiley
Date: 19-11-2012
DOI: 10.1111/JEB.12028
Abstract: In species where males provide neither direct benefits nor paternal care, it is typically assumed that female preferences are maintained by indirect selection reflecting genetic benefits to offspring of preferred males. However, it remains unclear whether populations harbour sufficient genetic variation in fitness to support costly female preferences - a problem called the 'lek paradox'. Here, we ask whether indirect selection on female preferences can be maintained by nongenetic inheritance. We construct a general model that can be used to represent either genetic or nongenetic inheritance, depending on the choice of parameter values. Interestingly, we find that costly preference is most likely to evolve and persist when fitness depends on an environmentally induced factor that can be transmitted over a single generation only, such as an environment-dependent paternal effect. Costly preference can also be supported when fitness depends on a highly mutable factor that can persist over multiple generations, such as an epigenetic mark, but the necessary conditions are more restrictive. Our findings show that nongenetic inheritance provides a plausible hypothesis for the maintenance of costly female preferences in species where males provide no direct benefits to females. Nongenetic paternal inheritance of fitness can occur in species lacking conventional forms of paternal care. Indeed, transmission of paternal condition via sperm-borne nongenetic factors may be more likely to evolve than conventional forms of paternal investment because sperm-borne effects are protected from cuckoldry. Our results furnish a novel ex le of an interaction between genetic and nongenetic inheritance that can lead to otherwise unexpected evolutionary outcomes.
Maternal and paternal condition effects on offspring phenotype in Telostylinus angusticollis (Diptera: Neriidae)
Publisher: Wiley
Date: 11-2007
DOI: 10.1111/J.1420-9101.2007.01419.X
Abstract: It is widely recognized that maternal phenotype can have important effects on offspring, but paternal phenotype is generally assumed to have no influence in animals lacking paternal care. Nonetheless, selection may favour the transfer of environmentally acquired condition to offspring from both parents. Using a split-brood, cross-generational laboratory design, we manipulated a key environmental determinant of condition - larval diet quality - of parents and their offspring in the fly Telostylinus angusticollis, in which there is no evidence of paternal provisioning. Parental diet did not affect offspring survival, but high-condition mothers produced larger eggs, and their offspring developed more rapidly when on a poor larval diet. Maternal condition had no effect on adult body size of offspring. By contrast, large, high-condition fathers produced larger offspring, and follow-up assays showed that this paternal effect can be sufficient to increase mating success of male offspring and fecundity of female offspring. Our findings suggest that both mothers and fathers transfer their condition to offspring, but with effects on different offspring traits. Moreover, our results suggest that paternal effects can be important even in species lacking conventional forms of paternal care. In such species, the transfer of paternal condition to offspring could contribute to indirect selection on female mate preferences.
The evolution of genomic imprinting: theories, predictions and empirical tests
Publisher: Springer Science and Business Media LLC
Date: 23-04-2014
DOI: 10.1038/HDY.2014.29
Sexual Conflict, Facultative Asexuality, and the True Paradox of Sex
Publisher: Elsevier BV
Date: 09-2017
DOI: 10.1016/J.TREE.2017.06.002
Abstract: Theory suggests that occasional or conditional sex involving facultative switching between sexual and asexual reproduction is the optimal reproductive strategy. Therefore, the true 'paradox of sex' is the prevalence of obligate sex. This points to the existence of powerful, general impediments to the invasion of obligately sexual populations by facultative mutants, and recent studies raise the intriguing possibility that a key impediment could be sexual conflict. Using Bateman gradients we show that facultative asexuality can lify sexual conflict over mating, generating strong selection for both female resistance and male coercion. We hypothesize that invasions are most likely to succeed when mutants have negative Bateman gradients, can avoid mating, and achieve high fecundity through asexual reproduction - a combination unlikely to occur in natural populations.
Experimental evidence of condition-dependent sexual dimorphism in the weakly dimorphic antler fly Protopiophila litigata (Diptera: Piophilidae)
Publisher: Oxford University Press (OUP)
Date: 11-05-2015
DOI: 10.1111/BIJ.12549
What are parental condition-transfer effects and how can they be detected?
Publisher: Wiley
Date: 06-11-2018
Developmental diet irreversibly shapes male post-copulatory traits in the neriid fly Telostylinus angusticollis
Publisher: Wiley
Date: 27-10-2018
DOI: 10.1111/JEB.13384
Abstract: Nutrient availability has been shown to influence investment in many fitness-related traits, including male reproductive success. Many studies have demonstrated that a reduction in nutrient availability alters male post-copulatory trait expression, with some studies demonstrating an effect of developmental nutrients and others, an effect of adult nutrients. However, few studies have manipulated both developmental and adult nutrients in the same experiment. Therefore, it is not clear what life-stage has the greatest effect on post-copulatory trait expression, and if the effects of developmental and adult nutrients can interact. Here, we investigate effects of developmental and adult nutrition on male testes and accessory gland size, sperm movement within the female reproductive tract and sperm length in the neriid fly, Telostylinus angusticollis. We found that males fed a nutrient-poor developmental diet produced sperm with a reduced tail beat frequency and had smaller testes and accessory glands compared to males fed a nutrient-rich developmental diet. In contrast, we found no effects of adult nutrition on any traits measured, although sperm length was correlated with body size and male age but unaffected by nutrition at any stage. Therefore, investment in adult post-copulatory traits is determined early on by developmental nutrients in male neriid flies, and this effect is not altered by adult nutrient availability.
Why do the well-fed appear to die young?: A new evolutionary hypothesis for the effect of dietary restriction on lifespan
Publisher: Wiley
Date: 07-03-2014
Abstract: Dietary restriction (DR) famously extends lifespan and reduces fecundity across a erse range of species. A prominent hypothesis suggests that these life-history responses evolved as a survival-enhancing strategy whereby resources are redirected from reproduction to somatic maintenance, enabling organisms to weather periods of resource scarcity. We argue that this hypothesis is inconsistent with recent evidence and at odds with the ecology of natural populations. We consider a wealth of molecular, medical, and evolutionary research, and conclude that the lifespan extension effect of DR is likely to be a laboratory artifact: in contrast with captivity, most animals living in natural environments may fail to achieve lifespan extension under DR. What, then, is the evolutionary significance of the suite of responses that extend lifespan in the laboratory? We suggest that these responses represent a highly conserved nutrient recycling mechanism that enables organisms to maximize immediate reproductive output under conditions of resource scarcity.
What is a paternal effect?
Publisher: Elsevier BV
Date: 10-2014
DOI: 10.1016/J.TREE.2014.07.009
Abstract: Maternal effects are now universally recognised as a form of nongenetic parental influence on offspring but, until recently, paternal effects were regarded as an anomaly. Although it is now clear that paternal effects are both widespread and important, their proximate basis and evolutionary consequences have received little attention and remain poorly understood. In particular, because many paternal effects are mediated by maternal responses such as differential allocation, the boundary between paternal and maternal effects is sometimes blurred. We distinguish here three basic types of paternal effect and clarify the role of maternal responses in these effects. We also outline key questions that can serve as a road map for research on the proximate basis and evolutionary implications of paternal effects.
Sex differences in survival costs of homosexual and heterosexual interactions: evidence from a fly and a beetle
Publisher: Elsevier BV
Date: 06-2009
Ontogenetic timing as a condition-dependent life history trait: High-condition males develop quickly, peak early, and age fast
Publisher: Wiley
Date: 28-01-2017
DOI: 10.1111/EVO.13172
Abstract: Within-population variation in ageing remains poorly understood. In males, condition-dependent investment in secondary sexual traits may incur costs that limit ability to invest in somatic maintenance. Moreover, males often express morphological and behavioral secondary sexual traits simultaneously, but the relative effects on ageing of investment in these traits remain unclear. We investigated the condition dependence of male life history in the neriid fly Telostylinus angusticollis. Using a fully factorial design, we manipulated male early-life condition by varying nutrient content of the larval diet and, subsequently, manipulated opportunity for adult males to interact with rival males. We found that high-condition males developed more quickly and reached their reproductive peak earlier in life, but also experienced faster reproductive ageing and died sooner than low-condition males. By contrast, interactions with rival males reduced male lifespan but did not affect male reproductive ageing. High-condition in early life is therefore associated with rapid ageing in T. angusticollis males, even in the absence of damaging male-male interactions. Our results show that abundant resources during the juvenile phase are used to expedite growth and development and enhance early-life reproductive performance at the expense of late-life performance and survival, demonstrating a clear link between male condition and ageing.
Layered sexual selection: A comparative analysis of sexual behaviour within an assemblage of piophilid flies
Publisher: Canadian Science Publishing
Date: 03-2003
DOI: 10.1139/Z03-031
Abstract: Although many theoretical and empirical studies have addressed the dynamics of sexual selection, little is known about the evolution of multiple sexual-selection mechanisms within the same system. I performed a qualitative comparative study of sexual behaviours in seven sympatric species of piophilid flies to identify and compare the apparent mechanisms of sexual selection operating in each system. In each of the seven species I observed several distinct types of malemale and malefemale interactions, potentially representing multiple mechanisms of sexual selection. Malemale interactions included scramble competition and, in some species, bouts of intense combat. Malefemale interactions exhibited two distinct patterns: (1) some form of premounting courtship followed by a simple copulatory sequence or (2) no premounting courtship but palpation behaviours during the copulatory sequence. Either pattern was combined with malefemale struggle in some species. In two species, male mating success also appeared to depend on the ability to overcome a "revealing obstacle", a female adaptation that exposed variation in male performance without direct assessment or struggle. In each species these mechanisms operated in a rough sequence and thus could be viewed as "layers" of sexual selection, with each layer potentially reducing the subset of in iduals that have opportunities to compete in the next layer. A brief review of the literature suggests that layered sexual selection is the typical pattern in many animal groups and thus may have important evolutionary consequences.
Genetic and phenotypic consequences of local transitions between sexual and parthenogenetic reproduction in the wild
Publisher: Cold Spring Harbor Laboratory
Date: 03-11-2022
DOI: 10.1101/2022.11.02.514965
Abstract: Transitions from sexual to asexual reproduction have occurred in numerous lineages across the tree of life, but it remains unclear why asexual populations rarely persist. In facultatively parthenogenetic animals, all-female populations can arise when males are absent or become extinct, and such populations can give rise to obligately asexual species. Facultative parthenogens could therefore shed light on the initial stages of transitions to asexuality, and the factors that determine the success or failure of asexual populations. Here, we describe a novel spatial mosaic of mixed-sex and all-female populations of the facultatively parthenogenetic Australian phasmid Megacrania batesii , and use this system to investigate the consequences of reproductive mode variation in the wild. Analysis of single nucleotide polymorphisms (SNPs) indicated multiple, independent transitions between reproductive modes. As expected, all-female populations had drastically reduced heterozygosity and genetic ersity relative to mixed-sex populations. However, we found few consistent differences in fitness-related traits between population types. All-female populations exhibited more frequent and severe (non-functional) wing deformities, but did not show higher rates of appendage loss. All-female populations also harbored more parasites, but only in certain habitats. Reproductive mode explained little variation in female body size, fecundity, or egg hatch-rate. Our results confirm that transitions to parthenogenetic reproduction can lead to dramatic reductions in genetic ersity and heterozygosity. However, our findings also suggest that asexual M. batesii populations consist of high-fitness genotypes that might be able to thrive for many generations, perhaps until they encounter a drastic environmental change to which they are unable to adapt.
Phenotypes optimized for early-life reproduction exhibit faster somatic deterioration with age, revealing a latent cost of high condition
Publisher: Wiley
Date: 07-09-2016
DOI: 10.1111/JEB.12968
Abstract: High condition enables in iduals to express a phenotype with greater reproductive potential. However, life-history theory predicts that reproduction will trade off with somatic maintenance and viability, and several studies have reported faster age-related decline in performance in high-condition in iduals, suggesting that high condition in early life is associated with accelerated somatic deterioration. This trade-off may be especially pronounced in males, which often express condition-dependent secondary sexual traits that can impose viability costs during development and through damage-inflicting adult sexual behaviours. To test this prediction, we reared larvae of the neriid fly Telostylinus angusticollis on diets of varying nutrient content and quantified somatic deterioration in solitary males, males housed in all-male or mixed-sex groups and immobilized males subjected to mechanical stress. We found that males reared on a nutrient-rich larval diet (high-condition males) suffered a higher rate of somatic deterioration with age, particularly when housed in groups. Perhaps as a result of accelerated somatic deterioration, high-condition males did not outlive low-condition males. In addition, high-condition males housed in all-male groups experienced a greater reduction in escape response with age than males housed in mixed-sex groups, suggesting that male-male combat promotes somatic deterioration. However, even when immobilized, high-condition males were still found to be more susceptible to somatic damage than low-condition males. Our findings suggest that a high-condition male phenotype is more prone to somatic damage, both as a result of associated behaviours such as combat, and because of the inherent fragility of the high-condition body.
Genital and body allometry in two species of noctuid moths (Lepidoptera: Noctuidae)
Publisher: Oxford University Press (OUP)
Date: 11-05-2015
DOI: 10.1111/BIJ.12550
Exoskeleton ageing and its relation to longevity and fecundity in female Australian leaf insects (
Publisher: CSIRO Publishing
Date: 13-05-2022
DOI: 10.1071/ZO21052
Abstract: Senescence is a decline in reproduction and survival rate with advancing age resulting from deterioration of somatic tissues and systems throughout the body. Age-related somatic changes (somatic ageing) have been studied extensively in vertebrates but are less well known in other animals, including insects. Since adult insects have very limited ability to repair their exoskeleton, somatic ageing could involve deterioration and discolouration of the cuticle. We investigated age-related changes in wing pigmentation and abdominal cuticle necrosis in females of the Australian leaf insect Phyllium monteithi. Adult females varied markedly in the extent and pattern of pigmentation on their bodies, and we found that pigment spots on the forewings increased in size with age in most in iduals. As females aged, most in iduals also exhibited increasing levels of abdominal cuticle necrosis, resulting in the loss of abdominal cuticle along the margin of the abdomen. Neither the extent of pigmentation nor cuticle loss were clearly associated with reduced fecundity or longevity in the protected laboratory environment, but it remains unknown whether these age-related changes have functional implications in the wild. Our results show that the P. monteithi exoskeleton undergoes complex changes with age, with potential implications for functional traits and fitness.
Does female resistance to mating select for live‐fast‐die‐young strategies in males? A comparative analysis in the genus Drosophila
Publisher: Wiley
Date: 02-10-2022
DOI: 10.1111/JEB.13937
Abstract: Female promiscuity is a pervasive selective force on male reproductive traits, and the strength of sexual selection is predicted to influence the trade‐off between lifespan and reproduction. In species where sexual selection is intense, males are predicted to invest in sexual strategies that shorten their lifespan, potentially resulting in female‐biased sexual dimorphism in longevity. However, comparative analyses have provided contrasting results, potentially due to the use of broad mating system categories or sexual size dimorphism as a proxy for sexual selection. Here, we used female remating rate (i.e. female promiscuity) as a more direct measure of sexual selection strength and conducted a phylogenetic comparative analysis of the relationship between female remating rate and sexual dimorphism in lifespan in 29 species of Drosophila . We did not find strong evidence that female remating rate was correlated with sexual dimorphism in lifespan. However, we found that male and female lifespans are positively correlated among species and that phylogeny and residual variance (i.e. variation in non‐phylogenetic factors) are important in determining female remating rate, male and female lifespans separately, and the correlation between male and female lifespan. We suggest that variation in the nature of sexual competition and variation between studies could account for some of the unexplained variation among species in the relation between female remating rate and sexual dimorphism in lifespan.
The evolution of insect mating systems, thirty years after
Publisher: Wiley
Date: 27-04-2015
DOI: 10.1111/EVO.12647
Sexual conflict mediated by ecological sex differences can generate diverse patterns of transgenerational plasticity
Publisher: Cold Spring Harbor Laboratory
Date: 20-11-2019
DOI: 10.1101/846287
Abstract: Transgenerational plasticity (TGP) occurs when the environment experienced by parents induces changes in traits of offspring and/or subsequent generations. Such effects can be adaptive or non-adaptive and are increasingly recognised as key determinants of health, cognition, development and performance across a wide range of taxa, including humans. While the conditions that favour maternal TGP are well understood, rapidly accumulating evidence indicates that TGP can be maternal or paternal, and offspring responses can be sex-specific. However, the evolutionary mechanisms that drive this ersity are unknown. We used an in idual-based model to investigate the evolution of TGP when the sexes experience different ecologies. We find that adaptive TGP rarely evolves when alleles at loci that determine offspring responses to environmental information originating from the mother and father are subject to sexually antagonistic selection. By contrast, duplication and sex-limitation of such loci can allow for the evolution of a variety of sex-specific responses, including non-adaptive sex-specific TGP when sexual selection is strong. Sexual conflict could therefore help to explain why adaptive TGP evolves in some species but not others, why sons and daughters respond to parental signals in different ways, and why complex patterns of sex-specific TGP may often be non-adaptive.
Sexual competition and the evolution of condition-dependent ageing
Publisher: Oxford University Press (OUP)
Date: 02-2018
DOI: 10.1002/EVL3.36
Abstract: Increased in idual resources (condition) can be correlated with either increased or decreased longevity. While variation in resource acquisition and allocation can account for some of this variation, the general conditions that select for either pattern remain unclear. Previous models suggest that nonlinearity of payoffs from investment in reproduction (e.g., male secondary sexual traits) can select for high-condition in iduals that sacrifice longevity to increase reproductive opportunity. However, it remains unclear what mating systems or patterns of sexual competition might select for such life-history strategies. We used a model of condition-dependent investment to explore how expected payoffs from increased expression of secondary sexual traits affect optimal investment in lifespan. We find that nonlinearity of these payoffs results in a negative relationship between condition and lifespan under two general conditions: first, when there are accelerating marginal benefits from increasing investment second, when in iduals that invest minimally in secondary sexual trait expression can still achieve matings. In the second scenario, the negative relationship occurs due to selection on low-condition in iduals to extend lifespan at the cost of secondary sexual trait expression. Our findings clarify the potential role of sexual selection in shaping patterns of condition-dependent ageing, and highlight the importance of considering the strategies of both low- and high-condition in iduals when investigating patterns of condition-dependent ageing.
Paternal Effects on Offspring Fitness Reflect Father's Social Environment
Publisher: Springer Science and Business Media LLC
Date: 30-11-2013
Sexual Conflict
Publisher: Wiley
Date: 15-09-2016
Eliminating autocorrelation reduces biological relevance of home range estimates
Publisher: Wiley
Date: 03-1999
Differential effects of genetic vs. environmental quality in Drosophila melanogaster suggest multiple forms of condition dependence
Publisher: Wiley
Date: 02-02-2015
DOI: 10.1111/ELE.12412
Abstract: Condition is a central concept in evolutionary ecology, but the roles of genetic and environmental quality in condition-dependent trait expression remain poorly understood. Theory suggests that condition integrates genetic, epigenetic and somatic factors, and therefore predicts alignment between the phenotypic effects of genetic and environmental quality. To test this key prediction, we manipulated both genetic (mutational) and environmental (dietary) quality in Drosophila melanogaster and examined responses in morphological and chemical (cuticular hydrocarbon, CHC) traits in both sexes. While the phenotypic effects of diet were consistent among genotypes, effects of mutation load varied in magnitude and direction. Average effects of diet and mutation were aligned for most morphological traits, but non-aligned for the male sexcombs and CHCs in both sexes. Our results suggest the existence of distinct forms of condition dependence, one integrating both genetic and environmental effects and the other purely environmental. We propose a model to account for these observations.
Quantitative genetics of wild populations of arthropods
Publisher: Oxford University PressOxford
Date: 10-04-2014
DOI: 10.1093/ACPROF:OSO/9780199674237.001.0001
Abstract: This book gathers the expertise of thirty evolutionary biologists from around the globe to highlight how applying the field of quantitative genetics (the analysis of the genetic basis of complex traits) to wild populations has provided major advancements in evolutionary ecology. It offers insights into the relevant methods and major discoveries in a wide array of evolutionary fields, such as life-history theory, behavioural ecology, and sexual selection, as well as the most promising emerging topics including the application to non-model taxa such as plants and arthropods, molecular quantitative genetics, and non-additive genetic variance.
Mating Males: An Evolutionary Perspective on Mammalian Reproduction. By Timothy Glover. Cambridge and New York: Cambridge University Press
Publisher: University of Chicago Press
Date: 12-2013
DOI: 10.1086/673801
Parental breeding age effects on descendants’ longevity interact over 2 generations in matrilines and patrilines
Publisher: Public Library of Science (PLoS)
Date: 25-11-2019
The implications of nongenetic inheritance for evolution in changing environments
Publisher: Wiley
Date: 08-11-2011
DOI: 10.1111/J.1752-4571.2011.00213.X
Abstract: Nongenetic inheritance is a potentially important but poorly understood factor in population responses to rapid environmental change. Accumulating evidence indicates that nongenetic inheritance influences a erse array of traits in all organisms and can allow for the transmission of environmentally induced phenotypic changes (‘acquired traits’), as well as spontaneously arising and highly mutable variants. We review models of adaptation to changing environments under the assumption of a broadened model of inheritance that incorporates nongenetic mechanisms of transmission, and survey relevant empirical ex les. Theory suggests that nongenetic inheritance can increase the rate of both phenotypic and genetic change and, in some cases, alter the direction of change. Empirical evidence shows that a ersity of phenotypes – spanning a continuum from adaptive to pathological – can be transmitted nongenetically. The presence of nongenetic inheritance therefore complicates our understanding of evolutionary responses to environmental change. We outline a research program encompassing experimental studies that test for transgenerational effects of a range of environmental factors, followed by theoretical and empirical studies on the population‐level consequences of such effects.
Development time mediates the effect of larval diet on ageing and mating success of male antler flies in the wild
Publisher: The Royal Society
Date: 04-11-2020
Abstract: High-quality developmental environments often improve in idual performance into adulthood, but allocating toward early life traits, such as growth, development rate and reproduction, may lead to trade-offs with late-life performance. It is, therefore, uncertain how a rich developmental environment will affect the ageing process (senescence), particularly in wild insects. To investigate the effects of early life environmental quality on insect life-history traits, including senescence, we reared larval antler flies ( Protopiophila litigata ) on four diets of varying nutrient concentration, then recorded survival and mating success of adult males released in the wild. Declining diet quality was associated with slower development, but had no effect on other life-history traits once development time was accounted for. Fast-developing males were larger and lived longer, but experienced more rapid senescence in survival and lower average mating rate compared to slow developers. Ultimately, larval diet, development time and body size did not predict lifetime mating success. Thus, a rich environment led to a mixture of apparent benefits and costs, mediated by development time. Our results indicate that ‘silver spoon' effects can be complex and that development time mediates the response of adult life-history traits to early life environmental quality.
The genomic distribution of sex-biased genes in Drosophila serrata: X chromosome demasculinization, feminization, and hyperexpression in both sexes
Publisher: Oxford University Press (OUP)
Date: 10-2013
DOI: 10.1093/GBE/EVT145
Sexual behaviour: Conflict, cooperation and coevolution
Publisher: Cambridge University Press
Date: 18-11-2010
Sex effects on life span and senescence in the wild when dates of birth and death are unknown
Publisher: Wiley
Date: 06-2009
DOI: 10.1890/08-0048.1
Abstract: Males and females allocate and schedule reproductive effort in very different ways. Because the timing and amount of reproductive effort influence survival and thus the optimization of life histories, mortality and senescence are predicted to be sex specific. However, age‐specific mortality rates of wild animals are often difficult to quantify in natural populations. Studies that report mortality rates from natural populations are, therefore, almost entirely confined to long‐lived, easy‐to‐track species such as large mammals and birds. Here, we employ a novel approach using capture–mark–recapture data from a wild population of black field crickets ( Teleogryllus commodus ) to test for sex differences in demographic aging. In this species, the age of captured adults cannot be readily determined, and animals cannot be reliably captured or observed every night, resulting in demographic data on in iduals whose dates of birth and death are unknown. We implement a recently developed life‐table analysis for wild‐caught in iduals of unknown age, in combination with a well‐established capture–mark–recapture methodology that models probabilistic dates of death. This unified analytical framework makes it possible to test for aging in wild, hard‐to‐track animals. Using these methods to fit Gompertz models of age‐specific mortality, we show that male crickets have higher mortality rates throughout life than female crickets. Furthermore, males and females both exhibit increasing mortality rates with age, indicating senescence, but the rate of senescence is not sex specific. Thus, observed sex differences in longevity are probably due to differences in baseline mortality rather than aging. Our findings illustrate the complexity of the relationships between sex, background mortality, and senescence rate in wild populations, showing that the elevated mortality rate of males need not be coupled with an elevated rate of aging.
Dietary protein and lifespan across the metamorphic boundary: Protein-restricted larvae develop into short-lived adults
Publisher: Springer Science and Business Media LLC
Date: 29-06-2015
DOI: 10.1038/SREP11783
Abstract: Restriction of nutrients in the adult diet extends lifespan across a erse range of species, but less is known about the long-term effects of developmental dietary restriction. In particular, it is not known whether adult lifespan is influenced by developmental caloric restriction or macronutrient balance. We used the nutritional geometry approach to independently manipulate protein and carbohydrate contents of the larval diet in the neriid fly, Telostylinus angusticollis, and measured adult lifespan. We found that adult male and female lifespan was shortest when larvae were fed a protein restricted diet. Thus, protein restriction in the larval diet has the opposite effect of protein restriction in the adult diet (which prolongs life in this species and across a wide range of taxa). Adult lifespan was unaffected by larval dietary carbohydrate. These patterns persisted after controlling for larval diet effects on adult body size. We propose that larval and adult protein sources are used for distinct metabolic tasks: during development, dietary protein is used to build a durable soma that enhances adult lifespan, although excessive protein consumption partially reverses this effect.
Sex-specific fitness consequences of nutrient intake and the evolvability of diet preferences
Publisher: University of Chicago Press
Date: 07-2013
DOI: 10.1086/670649
Abstract: The acquisition of nutrients is fundamental for the maintenance of bodily functions, growth, and reproduction in animals. As a result, fitness can be maximized only when animals are able to direct their attention to foods that reflect their current nutritional needs. Despite significant literature documenting the fitness consequences of nutrient composition and preference, less is known about the underlying genetic architecture of the dietary preferences themselves, specifically, the degree to which they can respond to selection. We addressed this by integrating evolutionary quantitative genetics and nutritional geometry to examine the shape of the sex-specific fitness surfaces and the availability of genetic variance for macronutrient preferences in the fruit fly Drosophila melanogaster. Combining these analyses, we found that the microevolutionary potential of carbohydrate and protein preference was above average in this population, because the expected direction of selection was relatively well aligned with the major axis of the genetic variance-covariance matrix, G. We also found that potential exists for sexually antagonistic genetic constraint in this system macronutrient blends maximizing fitness differed between the sexes, and cross-sex genetic correlations for their consumption were positive. However, both sexes were displaced from their feeding optima, generating similar directional selection on males and females, with the combined effect being that minimal sex-specific genetic constraints currently affect dietary preferences in this population.
The lifespan-reproduction trade-off under dietary restriction is sex-specific and context-dependent
Publisher: Elsevier BV
Date: 06-2013
DOI: 10.1016/J.EXGER.2013.03.007
Abstract: Adult dietary restriction (DR) extends lifespan, but the mechanisms that underlie this effect are not well understood. Many DR studies have demonstrated that lifespan extension tends to be accompanied by a reduction in female fecundity - a correlation widely interpreted as evidence that DR triggers an adaptive re - allocation of resources from reproduction to somatic maintenance. Yet, recent evidence suggests that survival and fecundity need not always trade off under DR, calling the re-allocation hypothesis into question. Because the effects of DR on both survival and reproduction have rarely been tested in both sexes, or under a range of ecologically-relevant environments, the generality of this trade-off remains unclear. We examined the effects of DR on survival and reproduction in both sexes and across a range of environments (larval diet quality and adult sex ratio) in the neriid fly Telostylinus angusticollis. We found that the lifespan-reproduction trade-off is both context- and sex-dependent. Although DR extended lifespan in both sexes by 65% and rendered females completely infertile, costs of DR on male fecundity were subtle and evident only in particular environmental combinations. Our findings suggest that a re-allocation of resources may not underlie the lifespan extension response to DR. Instead, full feeding may be associated with increased costs in comparison to DR, such that lifespan extension may be achieved without an increased resource investment to the soma.
Asymmetric reproductive isolation and interference in neriid flies: the roles of genital morphology and behaviour
Publisher: Elsevier BV
Date: 12-2012
The evolution of condition-dependent sexual dimorphism
Publisher: University of Chicago Press
Date: 2007
DOI: 10.1086/510214
Abstract: Theory suggests that the net benefit of allocating resources to a sexual trait depends both on the strength of sexual selection on that trait and on in idual condition. This predicts a tight coevolution between sexual dimorphism and condition dependence and suggests that these patterns of within-sex and between-sex variation may share a common genetic and developmental basis. Although condition-dependent expression of sexual traits is widely documented, the extent of covariation between condition dependence and sexual dimorphism remains poorly known. I investigated the effects of condition (larval diet quality) on multivariate sexual dimorphism in the fly Telostylinus angusticollis (Neriidae). Condition determined the direction of sexual size dimorphism and modulated sexual shape dimorphism by affecting allometric slopes and/or intercepts of sexually homologous traits in both sexes. Although the greatest responses to condition manipulation were observed in male sexual traits, both sexual and nonsexual traits exhibited substantial variation in the nature and magnitude of condition effects. Nonetheless, condition dependence and sexual dimorphism were remarkably congruent: variation in the strength of condition effects on male traits explained more than 90% of the variation in the magnitude of sexual dimorphism, whether quantified in terms of trait size or allometric slope. The genetic mechanisms that give rise to multivariate sexual dimorphism in body shape thus function in a strongly condition-dependent manner in this species, suggesting a common genetic basis for body shape variation within and between sexes.
A comparison of two methods for estimating measurement repeatability in morphometric studies
Publisher: Cold Spring Harbor Laboratory
Date: 09-05-2020
DOI: 10.1101/2020.05.07.083428
Abstract: Measurement repeatability is often reported in morphometric studies as an index of the contribution of measurement error to trait measurements. However, the common method of remeasuring a mounted specimen fails to capture some components of measurement error, and could therefore yield inflated repeatability estimates. Remounting specimens between successive measurements is likely to provide more realistic estimates of repeatability, particularly for small structures that are difficult to measure. Using measurements of 22 somatic and genitalic traits of the neriid fly Telostylinus angusticollis , we compared repeatability estimates obtained via remeasuring (where a mounted specimen is measured twice) versus remounting (where a specimen is remounted between measurements). We also asked whether the difference in repeatability estimates obtained via the two methods depends on trait size. Repeatability estimates obtained via remounting were lower than estimates obtained via remeasuring for each of the 22 traits, and the difference between estimates obtained via the two methods was generally greater for small structures (genitalic traits) than for large structures (legs, wings). Remounting specimens between successive measurements can provide more accurate estimates of measurement repeatability than remeasuring from a single mount, especially for small structures that are difficult to measure.
The paradox of obligate sex: the roles of sexual conflict and mate scarcity in transitions to facultative and obligate asexuality
Publisher: Cold Spring Harbor Laboratory
Date: 05-06-2017
DOI: 10.1101/146076
Abstract: Recent theory suggests that male coercion could contribute to the maintenance of obligate sex. However, it is unclear how sexually antagonistic coevolution might interact with mate scarcity to influence the probability of invasions of obligately sexual populations by mutants capable of parthenogenetic reproduction. Furthermore, if invasion does occur, it is unclear which factors promote or prevent the complete loss of sex. Using in idual-based models, we show that male coercion cannot prevent the invasion of a mutant allele that gives virgin females the ability to reproduce parthenogenetically because mutants always benefit by producing at least some offspring asexually prior to mating. Indeed, the likelihood of invasion generally increases as sexual conflict intensifies, and the effects of sexual conflict and mate scarcity can interact in complex ways to promote invasion. Nonetheless, we find that coercion prevents the complete loss of sex unless linkage disequilibrium can build up between the mutant allele and alleles for effective female resistance. Our findings clarify how costs and limitations of female resistance can promote the maintenance of sexual reproduction, turning sex into an evolutionary trap. At the same time, our results highlight the need to explain why facultative reproductive strategies so rarely evolve in nature.
Effects of genetic vs. environmental quality on condition‐dependent morphological and life history traits in a neriid fly
Publisher: Wiley
Date: 05-05-2022
DOI: 10.1111/JEB.14014
Abstract: Condition is assumed to reflect both genes and environment, enabling condition‐dependent signals to reveal genetic quality. However, because the phenotypic effects of variation in genetic quality could be masked by environmental heterogeneity, the contribution of genetic quality to phenotypic variation in fitness‐related traits and condition‐dependent signals remains unclear. We compared effects of ecologically relevant manipulations of environmental quality (nutrient dilution in the larval diet) and genetic quality (one generation of inbreeding) on male and female morphology, life history and reproductive performance in the neriid fly Telostylinus angusticollis . We found that larval diet quality had strong, positive effects on male and female body size, male secondary sexual traits, and aspects of male and female reproductive performance. By contrast, inbreeding had weak effects on most traits, and no trait showed clear and consistent effects of both environmental and genetic quality. Indeed, inbreeding effects on body size and male competitive performance were of opposite sign in rich vs. poor larval diet treatment groups. Our results suggest that environmental quality strongly affects condition, but the effects of genetic quality are subtle and environment‐dependent in this species. These findings raise questions about the genetic architecture of condition and the potential for condition‐dependent traits to function as signals of genetic quality.
Dietary restriction fails to extend life in stressful environments
Publisher: Cold Spring Harbor Laboratory
Date: 21-10-2022
DOI: 10.1101/2022.10.17.512576
Abstract: Moderate dietary restriction often prolongs life in laboratory animals, and this response has been interpreted as an adaptive strategy that promotes survival during famine. However, dietary restriction can also increase frailty, and it therefore remains unclear whether restricted diets prolong life under stressful conditions like those experienced by wild animals. We manipulated adult dietary protein of Drosophila melanogaster across a gradient of ambient temperature. We found that protein restriction increased longevity of both sexes at benign ambient temperatures (25-27°C), but failed to extend or even reduced longevity of flies maintained in cold (21-23°C) or hot (29°C) conditions. Protein restriction also generally reduced reproductive performance, and did not consistently enhance performance of F1, F2 or F3 descendants. Our results challenge the long-held idea that extended longevity of diet-restricted laboratory animals represents an adaptive survival strategy in natural populations, and suggest instead that this response is an artefact of benign laboratory conditions.
Sexual Dimorphism in Life History: Age, Survival, and Reproduction in Male and Female Field CricketsTeleogryllus commodusunder Seminatural Conditions
Publisher: University of Chicago Press
Date: 06-2009
DOI: 10.1086/598486
Abstract: Males and females differ in their reproductive strategies. Accordingly, sexually dimorphic optima in the allocation of resources to reproduction should select for sex-specific life histories, including sex-specific resolution of the key trade-off between reproduction and longevity. While males are expected to increase reproductive effort with increasing age under sexual selection theory, female reproductive effort should rather decrease after maturity, due to waning selection pressure at older ages. Sex differences in reproductive trade-offs and in the external mortality hazards experienced during the population's evolutionary history are both likely to shape sex differences in reproductive and actuarial (age-specific mortality) aging. Despite the importance of small-bodied, short-lived animals as laboratory models for life-history and aging studies, very little is known about sex differences in life-history patterns under natural conditions. Here, we tested for sex-specific patterns of reproductive and actuarial aging in field crickets under near-natural conditions. Both males and females showed actuarial senescence, with females exhibiting more rapid aging than males but with a later onset. Female and male reproductive effort showed a senescent decrease, with the peaks at different ages. Our findings provide the first demonstration of sexual dimorphism in age-dependent patterns of both survival and reproduction in an insect under near-natural conditions.
A comparison of two methods for estimating measurement repeatability in morphometric studies
Publisher: Wiley
Date: 2021
DOI: 10.1002/ECE3.7032
Sexual selection and allometry: A critical reappraisal of the evidence and ideas
Publisher: Wiley
Date: 04-2007
DOI: 10.1111/J.1558-5646.2007.00081.X
Abstract: One of the most pervasive ideas in the sexual selection literature is the belief that sexually selected traits almost universally exhibit positive static allometries (i.e., within a s le of conspecific adults, larger in iduals have disproportionally larger traits). In this review, I show that this idea is contradicted by empirical evidence and theory. Although positive allometry is a typical attribute of some sexual traits in certain groups, the preponderance of positively allometric sexual traits in the empirical literature apparently results from a s ling bias reflecting a fascination with unusually exaggerated (bizarre) traits. I review empirical ex les from a broad range of taxa illustrating the ersity of allometric patterns exhibited by signal, weapon, clasping and genital traits, as well as nonsexual traits. This evidence suggests that positive allometry may be the exception rather than the rule in sexual traits, that directional sexual selection does not necessarily lead to the evolution of positive allometry and, conversely, that positive allometry is not necessarily a consequence of sexual selection, and that many sexual traits exhibit sex differences in allometric intercept rather than slope. Such ersity in the allometries of secondary sexual traits is to be expected, given that optimal allometry should reflect resource allocation trade-offs, and patterns of sexual and viability selection on both trait size and body size. An unbiased empirical assessment of the relation between sexual selection and allometry is an essential step towards an understanding of this ersity.
Sex differences in nutrient-dependent reproductive ageing
Publisher: Wiley
Date: 26-05-2009
DOI: 10.1111/J.1474-9726.2009.00479.X
Abstract: Evolutionary theories of aging predict that fitness-related traits, including reproductive performance, will senesce because the strength of selection declines with age. Sexual selection theory predicts, however, that male reproductive performance (especially sexual advertisement) will increase with age. In both bodies of theory, diet should mediate age-dependent changes in reproductive performance. In this study, we show that the sexes exhibit dramatic, qualitative differences in age-dependent reproductive performance trajectories and patterns of reproductive ageing in the cricket Teleogryllus commodus. In females, fecundity peaked early in adulthood and then declined. In contrast, male sexual advertisement increased across the natural lifespan and only declined well beyond the maximum field lifespan. These sex differences were robust to deviations from sex-specific dietary requirements. Our results demonstrate that sexual selection can be at least as important as sex-dependent mortality in shaping the signal of reproductive ageing.
The ecology of sexual conflict: Background mortality can modulate the effects of male manipulation on female fitness
Publisher: Wiley
Date: 09-10-2014
DOI: 10.1111/EVO.12272
Abstract: Sexual and parental conflicts can arise because males benefit by inducing elevated reproductive effort in their mates. For females, the costs of such manipulation are often manifested later in life, and may therefore covary with female life expectancy. Here, I outline a simple female life-history model where female life expectancy reflects extrinsic mortality rate, and elevated reproductive effort causes accelerated senescence. Using this model, I show that variation in extrinsic mortality rate can modulate the magnitude and sign of fitness effects that male manipulation has on females. This result has several interesting implications. First, it suggests that the fitness effects of sexual interactions can depend on ecological factors, such as predation, that influence life expectancy. Second, if mortality risk is condition-dependent but reproductive effort is not fully optimized in relation to in idual condition, then sexual conflict intensity may increase with in idual condition, selecting for condition-dependent reproductive strategies. Third, if males vary in manipulativeness, then the fitness effects of mating with a given male phenotype may depend on both female condition and extrinsic mortality rate. Fourth, life span extension in the laboratory can lead to overestimation of sexual and parental conflicts. Life expectancy may therefore be a key factor in sexual coevolution.
Condition dependence of male and female genital structures in the seed beetle Callosobruchus maculatus (Coleoptera: Bruchidae)
Publisher: Wiley
Date: 15-06-2015
DOI: 10.1111/JEB.12659
Abstract: Theory predicts that costly secondary sexual traits will evolve heightened condition dependence, and many studies have reported strong condition dependence of signal and weapon traits in a variety of species. However, although genital structures often play key roles in intersexual interactions and appear to be subject to sexual or sexually antagonistic selection, few studies have examined the condition dependence of genital structures, especially in both sexes simultaneously. We investigated the responses of male and female genital structures to manipulation of larval diet quality (new versus once-used mung beans) in the bruchid seed beetle Callosobruchus maculatus. We quantified effects on mean relative size and static allometry of the male aedeagus, aedeagal spines, flap and paramere and the female reproductive tract and bursal spines. None of the male traits showed a significant effect of diet quality. In females, we found that longer bursal spines (relative to body size) were expressed on low-quality diet. Although the function of bursal spines is poorly understood, we suggest that greater bursal spine length in low-condition females may represent a sexually antagonistic adaptation. Overall, we found no evidence that genital traits in C. maculatus are expressed to a greater extent when nutrients are more abundant. This suggests that, even though some genital traits appear to function as secondary sexual traits, genital traits do not exhibit heightened condition dependence in this species. We discuss possible reasons for this finding.
SEX-SPECIFIC PATTERNS OF MORPHOLOGICAL DIVERSIFICATION: EVOLUTION OF REACTION NORMS AND STATIC ALLOMETRIES IN NERIID FLIES
Publisher: Wiley
Date: 16-10-2013
DOI: 10.1111/EVO.12276
Abstract: The consequences of sex-specific selection for patterns of ersification remain poorly known. Because male secondary sexual traits are typically costly to express, and both costs and benefits are likely to depend on ambient environment and in idual condition, such traits may be expected to ersify via changes in reaction norms as well as the scaling of trait size with body size (static allometry). We investigated morphological ersification within two species of Australian neriid flies (Telostylinus angusticollis, Telostylinus lineolatus) by rearing larvae from several populations on larval diets varying sixfold in nutrient concentration. Mean body size varied among populations of T. angusticollis, but body size reaction norms did not vary within either species. However, we detected ersification of reaction norms for body shape in males and females within both species. Moreover, unlike females, males also ersified in static allometry slope and reaction norms for static allometry slope of sexual and nonsexual traits. Our findings reveal qualitative sex differences in patterns of morphological ersification, whereby shape-size relationships ersify extensively in males, but remain conserved in females despite extensive evolution of trait means. Our results highlight the importance of incorporating plasticity and allometry in studies of adaptation and ersification.
THE ROLES OF LIFE-HISTORY SELECTION AND SEXUAL SELECTION IN THE ADAPTIVE EVOLUTION OF MATING BEHAVIOR IN A BEETLE
Publisher: Wiley
Date: 12-2009
DOI: 10.1111/J.1558-5646.2009.00904.X
Abstract: Although there is continuing debate about whether sexual selection promotes or impedes adaptation to novel environments, the role of mating behavior in such adaptation remains largely unexplored. We investigated the evolution of mating behavior (latency to mating, mating probability and duration) in replicate populations of seed beetles Callosobruchus maculatus subjected to selection on life-history ("Young" vs. "Old" reproduction) under contrasting regimes of sexual selection ("Monogamy" vs. "Polygamy"). Life-history selection is predicted to favor delayed mating in "Old" females, but sexual conflict under polygamy can potentially retard adaptive life-history evolution. We found that life-history selection yielded the predicted changes in mating behavior, but sexual selection regime had no net effect. In within-line crosses, populations selected for late reproduction showed equally reduced early-life mating probability regardless of mating system. In between-line crosses, however, the effect of life-history selection on early-life mating probability was stronger in polygamous lines than in monogamous ones. Thus, although mating system influenced male-female coevolution, removal of sexual selection did not affect the adaptive evolution of mating behavior. Importantly, our study shows that the interaction between sexual selection and life-history selection can result in either increased or decreased reproductive ergence depending on the ecological context.
Reappraising sexual coevolution and the sex roles
Publisher: Public Library of Science (PLoS)
Date: 08-12-2009
Dietary protein mediates a trade‐off between larval survival and the development of male secondary sexual traits
Publisher: Wiley
Date: 12-06-2013
Nongenetic inheritance for behavioral ecologists
Publisher: Oxford University Press (OUP)
Date: 14-08-2013
Senescence in wild insects: Key questions and challenges
Publisher: Wiley
Date: 21-07-2020
A New Nearctic Species of Protopiophila Duda (Diptera: Piophilidae), with Notes on its Behaviour and Comparison with P. Latipes (Meigen)
Publisher: Cambridge University Press (CUP)
Date: 12-1995
DOI: 10.4039/ENT127859-6
Abstract: Protopiophila litigata sp.nov. is described from Ontario and Nova Scotia. McAlpine’s (1977) key to the species of Protopiophila is modified to facilitate identification of the new species. Behaviours of P . litigata and P . latipes were studied in Algonquin Park, Ontario. Whereas P . latipes reproduces on corpses in advanced stages of decay, P . litigata mates and oviposits on discarded cervid antlers, ignoring other carrion. Unlike P . latipes , males of P . litigata engage in ’mate guarding’. These traits probably represent autapomorphies of P . litigata .
Environmental Effects on the Expression of Life Span and Aging: An Extreme Contrast between Wild and Captive Cohorts ofTelostylinus angusticollis(Diptera: Neriidae)
Publisher: University of Chicago Press
Date: 09-2008
DOI: 10.1086/589519
Abstract: Most research on life span and aging has been based on captive populations of short-lived animals however, we know very little about the expression of these traits in wild populations of such organisms. Because life span and aging are major components of fitness, the extent to which the results of many evolutionary studies in the laboratory can be generalized to natural settings depends on the degree to which the expression of life span and aging differ in natural environments versus laboratory environments and whether such environmental effects interact with phenotypic variation. We investigated life span and aging in Telostylinus angusticollis in the wild while simultaneously estimating these parameters under a range of conditions in a laboratory stock that was recently established from the same wild population. We found that males live less than one-fifth as long and age at least twice as rapidly in the wild as do their captive counterparts. In contrast, we found no evidence of aging in wild females. These striking sex-specific differences between captive and wild flies support the emerging view that environment exerts a profound influence on the expression of life span and aging. These findings have important implications for evolutionary gerontology and, more generally, for the interpretation of fitness estimates in captive populations.
Sex and Power: sexual dimorphism in trait variability and its eco-evolutionary and statistical implications
Publisher: Cold Spring Harbor Laboratory
Date: 26-05-2020
DOI: 10.1101/2020.05.23.106146
Abstract: Biomedical and clinical sciences are experiencing a renewed interest in the fact that males and females differ in many anatomic, physiological, and behavioral traits. Sex differences in trait variability, however, are yet to receive similar recognition. In medical science, mammalian females are assumed to have higher trait variability due to estrous cycles (the ‘estrus-mediated variability hypothesis’) historically in biomedical research, females have been excluded for this reason. Contrastingly, evolutionary theory and associated data support the ‘greater male variability hypothesis’. Here, we test these competing hypotheses in 218 traits measured in ,900 mice, using meta-analysis methods. Neither hypothesis could universally explain patterns in trait variability. Sex-bias in variability was trait-dependent. While greater male variability was found in morphological traits, females were much more variable in immunological traits. Sex-specific variability has eco-evolutionary ramifications including sex-dependent responses to climate change, as well as statistical implications including power analysis considering sex difference in variance.
Sexual dimorphism in trait variability and its eco-evolutionary and statistical implications
Publisher: eLife Sciences Publications, Ltd
Date: 17-11-2020
DOI: 10.7554/ELIFE.63170
Abstract: Biomedical and clinical sciences are experiencing a renewed interest in the fact that males and females differ in many anatomic, physiological, and behavioural traits. Sex differences in trait variability, however, are yet to receive similar recognition. In medical science, mammalian females are assumed to have higher trait variability due to estrous cycles (the ‘estrus-mediated variability hypothesis’) historically in biomedical research, females have been excluded for this reason. Contrastingly, evolutionary theory and associated data support the ‘greater male variability hypothesis’. Here, we test these competing hypotheses in 218 traits measured in ,900 mice, using meta-analysis methods. Neither hypothesis could universally explain patterns in trait variability. Sex bias in variability was trait-dependent. While greater male variability was found in morphological traits, females were much more variable in immunological traits. Sex-specific variability has eco-evolutionary ramifications, including sex-dependent responses to climate change, as well as statistical implications including power analysis considering sex difference in variance.
Genetic constraints on microevolutionary divergence of sex-biased gene expression
Publisher: The Royal Society
Date: 27-08-2018
Abstract: The evolution of sex-specific phenotypes is an important dimension of ersification and local adaptation. The sex-dependent regulation of gene expression is considered a key genomic mechanism facilitating sex-dependent adaptation. In many species, genes with male-biased expression evolve faster in DNA sequence and expression level than genes with female-biased or sexually monomorphic expression. While positive selection may be responsible for rapid DNA sequence evolution, why expression of male-biased genes also evolves rapidly remains unclear. Beyond sex differences in selection, some aspects of the genetic architecture of gene expression could contribute to the rapid evolution of male-biased gene expression. First, male-biased genes might simply have greater standing genetic variance than female-biased genes. Second, male-biased genes could be less constrained by pleiotropy, either within or between sexes. Here, we evaluate these alternative explanations on an intraspecific scale using a series of quantitative genetic experiments conducted on natural variation in male and female gene expression in the fly Drosophila serrata . Male-biased genes had significantly higher genetic variance than female-biased genes and were generally more narrowly expressed across tissues, suggesting lower within-in idual pleiotropy. However, consistent with stronger constraints due to between-sex pleiotropy, their between-sex genetic correlations, r MF , were higher than for female-biased genes and more strongly negatively associated with sex bias. Using an extensive clinal dataset, we tested whether sex differences in gene expression ergence among populations have been shaped by pleiotropy . Here too, male-biased gene ergence was more strongly associated with between-sex pleiotropy than was female-biased gene ergence. Systematic differences in genetic variance and pleiotropy may be important factors influencing sex-specific adaptation arising through changes in gene expression. This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences’.
The relative importance of genetic and nongenetic inheritance in relation to trait plasticity in C allosobruchus maculatus
Publisher: Wiley
Date: 16-11-2012
DOI: 10.1111/JEB.12014
Abstract: A trait's response to natural selection will reflect the nature of the inheritance mechanisms that mediate the transmission of variation across generations. The relative importance of genetic and nongenetic mechanisms of inheritance is predicted to be related to the degree of trait plasticity, with nongenetic inheritance playing a greater role in the cross-generational transmission of more plastic traits. However, this prediction has never been tested. We investigated the influence of genetic effects and nongenetic parental effects in two morphological traits differing in degree of plasticity by manipulating larval diet quality within a cross-generational split-brood experiment using the seed beetle Callososbuchus maculatus. In line with predictions, we found that the more plastic trait (elytron length) is strongly influenced by both maternal and paternal effects whereas genetic variance is undetectable. In contrast, the less plastic trait (first abdominal sternite length) is not influenced by parental effects but exhibits abundant genetic variance. Our findings support the hypothesis that environment-dependent parental effects may play a particularly important role in highly plastic traits and thereby affect the evolutionary response of such traits.
Author response: Sexual dimorphism in trait variability and its eco-evolutionary and statistical implications
Publisher: eLife Sciences Publications, Ltd
Date: 29-10-2020
The evolution of male mate choice in insects: A synthesis of ideas and evidence
Publisher: Wiley
Date: 08-2001
DOI: 10.1017/S1464793101005693
Abstract: Mate choice by males has been recognized at least since Darwin's time, but its phylogenetic distribution and effect on the evolution of female phenotypes remain poorly known. Moreover, the relative importance of factors thought to underlie the evolution of male mate choice (especially parental investment and mate quality variance) is still unresolved. Here I synthesize the empirical evidence and theory pertaining to the evolution of male mate choice and sex role reversal in insects, and examine the potential for male mating preferences to generate sexual selection on female phenotypes. Although male mate choice has received relatively little empirical study, the available evidence suggests that it is widespread among insects (and other animals). In addition to 'precopulatory' male mate choice, some insects exhibit 'cryptic' male mate choice, varying the amount of resources allocated to mating on the basis of female mate quality. As predicted by theory, the most commonly observed male mating preferences are those that tend to maximize a male's expected fertilization success from each mating. Such preferences tend to favour female phenotypes associated with high fecundity or reduced sperm competition intensity. Among insect species there is wide variation in mechanisms used by males to assess female mate quality, some of which (e.g. probing, antennating or repeatedly mounting the female) may be difficult to distinguish from copulatory courtship. According to theory, selection for male choosiness is an increasing function of mate quality variance and those reproductive costs that reduce, with each mating, the number of subsequent matings that a male can perform ('mating investment') Conversely, choosiness is constrained by the costs of mate search and assessment, in combination with the accuracy of assessment of potential mates and of the distribution of mate qualities. Stronger selection for male choosiness may also be expected in systems where female fitness increases with each copulation than in systems where female fitness peaks at a small number of matings. This theoretical framework is consistent with most of the empirical evidence. Furthermore, a variety of observed male mating preferences have the potential to exert sexual selection on female phenotypes. However, because male insects typically choose females based on phenotypic indicators of fecundity such as body size, and these are usually amenable to direct visual or tactile assessment, male mate choice often tends to reinforce stronger vectors of fecundity or viability selection, and seldom results in the evolution of female display traits. Research on orthopterans has shown that complete sex role reversal (i.e. males choosy, females competitive) can occur when male parental investment limits female fecundity and reduces the potential rate of reproduction of males sufficiently to produce a female-biased operational sex ratio. By contrast, many systems exhibiting partial sex role reversal (i.e. males choosy and competitive) are not associated with elevated levels of male parental investment, reduced male reproductive rates, or reduced male bias in the operational sex ratio. Instead, large female mate quality variance resulting from factors such as strong last-male sperm precedence or large variance in female fecundity may select for both male choosiness and competitiveness in such systems. Thus, partial and complete sex role reversal do not merely represent different points along a continuum of increasing male parental investment, but may evolve via different evolutionary pathways.
Nongenetic Inheritance and Its Evolutionary Implications
Publisher: Annual Reviews
Date: 12-2009
DOI: 10.1146/ANNUREV.ECOLSYS.39.110707.173441
Abstract: Modern evolutionary biology is founded on the Mendelian-genetic model of inheritance, but it is now clear that this model is incomplete. Empirical evidence shows that environment (encompassing all external influences on the genome) can impose transgenerational effects and generate heritable variation for a broad array of traits in animals, plants, and other organisms. Such effects can be mediated by the transmission of epigenetic, cytoplasmic, somatic, nutritional, environmental, and behavioral variation. Building on the work of many authors, we outline a general framework for conceptualizing nongenetic inheritance and its evolutionary implications. This framework shows that, by decoupling phenotypic change from the genotype, nongenetic inheritance can circumvent the limitations of genetic inheritance and thereby influence population dynamics and alter the fitness landscape. The weight of theory and empirical evidence indicates that nongenetic inheritance is a potent factor in evolution that can engender outcomes unanticipated under the Mendelian-genetic model.
The geography of sex: sexual conflict, environmental gradients and local loss of sex in facultatively parthenogenetic animals
Publisher: The Royal Society
Date: 27-08-2018
Abstract: Obligately asexual organisms tend to occur at higher altitudes or latitudes and occupy larger ranges than their obligately sexual relatives—a phenomenon called geographical parthenogenesis. Some facultatively parthenogenetic organisms that reproduce both sexually and asexually also exhibit spatial variation in reproductive mode. Theory suggests that sexual conflict and mate limitation can determine the relative frequency of sex in facultative parthenogens, but the effect of these dynamics on spatial distributions is unknown. Here, we use in idual-based models to investigate whether these dynamics can generate local differences in the reproductive mode in a facultatively parthenogenetic metapopulation occupying an environmental gradient. We find that selection for resistance and high fecundity creates positive epistasis in virgin females between a mutant allele for parthenogenesis and alleles for resistance, resulting in female-biased sex ratios and higher resistance and coercion towards the productive ‘core’ of the metapopulation. However, steeper environmental gradients, which lead to lower density and less mating at the ‘edge’, generate female bias without promoting coercion or resistance. Our analysis shows that local adaptation of facultatively parthenogenetic populations subject to sexual conflict and productivity gradients can generate striking spatial variation suggesting new patterns for empirical investigation. These findings could also help to explain the rarity of facultative parthenogenesis in animals. This article is part of the theme issue ‘Linking local adaptation with the evolution of sex differences'.
Condition dependence of phenotypic integration and the evolvability of genitalic traits in a neriid fly
Publisher: The Royal Society
Date: 05-2020
Abstract: The spectacular ersity of insect male genitalia, and their relative insensitivity to the environment, have long puzzled evolutionary biologists and taxonomists. We asked whether the unusual evolvability of male genitalia could be associated with low morphological integration of genitalic traits, by comparison with male somatic traits and female traits. We also asked whether this pattern was robust to variation in resource availability during development, which affects adult condition. To address these questions, we manipulated larval diet quality in a split-brood design and compared levels of integration of male and female genitalic and somatic traits in the neriid fly, Telostylinus angusticollis . We found that male genitalic traits were substantially less integrated than male somatic traits, and less integrated than female genitalic traits. Female genitalic traits were also less integrated than female somatic traits, but the difference was less pronounced than in males. However, integration of male genitalic traits was negatively condition-dependent, with high-condition males exhibiting lower trait integration than low-condition males. Finally, genitalic traits exhibited lower larval diet × family interactions than somatic traits. These results could help explain the unusually high evolvability of male genitalic traits in insects.
Intralocus sexual conflict
Publisher: Elsevier BV
Date: 05-2009
DOI: 10.1016/J.TREE.2008.12.005
Abstract: Intralocus sexual conflict occurs when selection on a shared trait in one sex displaces the other sex from its phenotypic optimum. It arises because many shared traits have a common genetic basis but undergo contrasting selection in the sexes. A recent surge of interest in this evolutionary tug of war has yielded evidence of such conflicts in laboratory and natural populations. Here we highlight outstanding questions about the causes and consequences of intralocus sexual conflict at the genomic level, and its long-term implications for sexual coevolution. Whereas recent thinking has focussed on the role of intralocus sexual conflict as a brake on sexual coevolution, we urge a broader appraisal that also takes account of its potential to drive adaptive evolution and speciation.
The role of sexual conflict in the evolution of facultative parthenogenesis: A study on the spiny leaf stick insect
Publisher: Elsevier BV
Date: 03-2015
The dissimilar costs of love and war: Age-specific mortality as a function of the operational sex ratio
Publisher: Wiley
Date: 07-03-2011
DOI: 10.1111/J.1420-9101.2011.02250.X
Abstract: Lifespan and ageing are strongly affected by many environmental factors, but the effects of social environment on these life-history traits are not well understood. We examined effects of social interaction on age-specific mortality rate in the sexually dimorphic neriid fly Telostylinus angusticollis. We found that although interaction with other in iduals reduced longevity of both sexes, the costs associated with variation in operational sex ratio were sex specific: males' early-life mortality rate increased, and lifespan decreased, with increasing male bias in the sex ratio, whereas surprisingly, the presence of males had no effect on early-life mortality or lifespan of females. Intriguingly, early-life (immediate) mortality costs did not covary with late-life (latent) costs. Rather, both sexes aged most rapidly in a social environment dominated by the opposite sex. Our findings suggest that distinct reproductive activities, such as mating and fighting, impose different age-specific patterns of mortality, and that such costs are strongly sex specific.
OFFSPRING SIZE VARIATION WITHIN BROODS AS A BET‐HEDGING STRATEGY IN UNPREDICTABLE ENVIRONMENTS
Publisher: Wiley
Date: 09-2008
DOI: 10.1890/07-0267.1
Abstract: Offspring size is strikingly variable within species. Although theory can account for variation in offspring size among mothers, an adaptive explanation for variation within in idual broods has proved elusive. Theoretical considerations of this problem assume that producing offspring that are too small results in reduced offspring viability, but producing offspring that are too large (for that environment) results only in a lost opportunity for increased fecundity. However, logic and recent evidence suggest that offspring above a certain size will also have lower fitness, such that mothers face fitness penalties on either side of an optimum. Although theory assuming intermediate optima has been developed for other ersification traits, the implications of this idea for selection on intra-brood variance in offspring size have not been explored theoretically. Here we model the fitness of mothers producing offspring of uniform vs. variable size in unpredictably variable environments and compare these two strategies under a variety of conditions. Our model predicts that producing variably sized offspring results in higher mean maternal fitness and less variation in fitness among generations when there is a maximum and minimum viable offspring size, and when many mothers under- or overestimate this optimum. This effect is especially strong when the viable offspring size range is narrow relative to the range of environmental variation. To determine whether this prediction is consistent with empirical evidence, we compared within- and among-mother variation in offspring size for five phyla of marine invertebrates with different developmental modes corresponding to contrasting levels of environmental predictability. Our comparative analysis reveals that, in the developmental mode in which mothers are unlikely to anticipate the relationship between offspring size and performance, size variation within mothers exceeds variation among mothers, but the converse is true when optimal offspring size is likely to be more predictable. Together, our results support the hypothesis that variation in offspring size within broods can reflect an adaptive strategy for dealing with unpredictably variable environments. We suggest that, when there is a minimum and a maximum viable offspring size and the environment is unpredictable, selection will act on both the mean and variance of offspring size.
The genetic architecture of sexual dimorphism: The potential roles of genomic imprinting and condition-dependence
Publisher: Oxford University PressOxford
Date: 05-07-2007
DOI: 10.1093/ACPROF:OSO/9780199208784.003.0020
Abstract: The first section of this chapter presents new theory showing that sex-specific patterns of genomic imprinting may play a role in the genetic architecture and expression of sexually dimorphic traits. Empirical evidence tentatively supports this novel theory. The second section considers the potential role of condition dependence in the evolution of sexual dimorphism. Life history theory predicts that sexual dimorphism and condition dependence will co-evolve because the degree of exaggeration of male secondary sexual traits by sexual selection is expected to reflect the viability costs of trait expression and, therefore, the benefits of condition dependence. This prediction is supported by positive covariation of sexual dimorphism and condition dependence among morphological traits. Condition dependence of male traits is also expected to reduce intersexual genetic correlations, and thus mitigate intralocus sexual conflict and facilitate the evolution of sexual dimorphism.
EVOLUTION OF MALE AND FEMALE GENITALIA FOLLOWING RELEASE FROM SEXUAL SELECTION
Publisher: Wiley
Date: 22-04-2011
DOI: 10.1111/J.1558-5646.2011.01309.X
Abstract: Despite the key functions of the genitalia in sexual interactions and fertilization, the role of sexual selection and conflict in shaping genital traits remains poorly understood. Seed beetle (Callosobruchus maculatus) males possess spines on the intromittent organ, and females possess a thickened reproductive tract wall that also bears spines. We investigated the role of sexual selection and conflict by imposing monogamous mating on eight replicate populations of this naturally polygamous insect, while maintaining eight other populations under polygamy. To establish whether responses to mating system manipulation were robust to ecological context, we simultaneously manipulated life-history selection (early/late reproduction). Over 18-21 generations, male genital spines evolved relatively reduced length in large males (i.e., shallower static allometry) in monogamous populations. Two nonintromittent male genital appendages also evolved in response to the interaction of mating system and ecology. In contrast, no detectable evolution occurred in female genitalia, consistent with the expectation of a delayed response in defensive traits. Our results support a sexually antagonistic role for the male genital spines, and demonstrate the evolution of static allometry in response to variation in sexual selection opportunity. We argue that further advances in the study of genital coevolution will require a much more detailed understanding of the functions of male and female genital traits.
Sexual selection, sexual conflict and the evolution of ageing and life span
Publisher: Wiley
Date: 16-05-2008
Ejaculate feeding and female fitness in the sexually dimorphic fly Prochyliza xanthostoma (Diptera: Piophilidae)
Publisher: Elsevier BV
Date: 02-2005
The complexity of male reproductive success: effects of nutrition, morphology, and experience
Publisher: Oxford University Press (OUP)
Date: 03-02-2015
Mapping the past, present and future research landscape of paternal effects
Publisher: Springer Science and Business Media LLC
Date: 27-11-2020
DOI: 10.1186/S12915-020-00892-3
Abstract: Although in all sexually reproducing organisms an in idual has a mother and a father, non-genetic inheritance has been predominantly studied in mothers. Paternal effects have been far less frequently studied, until recently. In the last 5 years, research on environmentally induced paternal effects has grown rapidly in the number of publications and ersity of topics. Here, we provide an overview of this field using synthesis of evidence (systematic map) and influence (bibliometric analyses). We find that motivations for studies into paternal effects are erse. For ex le, from the ecological and evolutionary perspective, paternal effects are of interest as facilitators of response to environmental change and mediators of extended heredity. Medical researchers track how paternal pre-fertilization exposures to factors, such as diet or trauma, influence offspring health. Toxicologists look at the effects of toxins. We compare how these three research guilds design experiments in relation to objects of their studies: fathers, mothers and offspring. We highlight ex les of research gaps, which, in turn, lead to future avenues of research. The literature on paternal effects is large and disparate. Our study helps in fostering connections between areas of knowledge that develop in parallel, but which could benefit from the lateral transfer of concepts and methods.
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