scholarly journals Sex-dependent dominance at a single locus maintains variation in age at maturity in Atlantic salmon

2015 ◽  
Author(s):  
Nicola J Barson ◽  
Tutku Aykanat ◽  
Kjetil Hindar ◽  
Matthew Baranski ◽  
Geir H Bolstad ◽  
...  
Keyword(s):  
Sexual Conflict ◽  
Balancing Selection ◽  
Age At Maturity ◽  
Sexual Antagonism ◽  
Substantial Impact ◽  
Intralocus Sexual Conflict ◽  
Snp Data ◽  
Fitness Trait ◽  
Males And Females ◽  
Spatially Varying Selection

Males and females share many traits that have a common genetic basis, however selection on these traits often differs between the sexes leading to sexual conflict. Under such sexual antagonism, theory predicts the evolution of genetic architectures that resolve this sexual conflict. Yet, despite intense theoretical and empirical interest, the specific genetic loci behind sexually antagonistic phenotypes have rarely been identified, limiting our understanding of how sexual conflict impacts genome evolution and the maintenance of genetic diversity. Here, we identify a large effect locus controlling age at maturity in 57 salmon populations, an important fitness trait in which selection favours earlier maturation in males than females, and show it is a clear example of sex dependent dominance reducing intralocus sexual conflict and maintaining adaptive variation in wild populations. Using high density SNP data and whole genome re-sequencing, we found that vestigial-like family member 3 (VGLL3) exhibits sex-dependent dominance in salmon, promoting earlier and later maturation in males and females, respectively. VGLL3, an adiposity regulator associated with size and age at maturity in humans, explained 39.4% of phenotypic variation, an unexpectedly high effect size for what is usually considered a highly polygenic trait. Such large effects are predicted under balancing selection from either sexually antagonistic or spatially varying selection. Our results provide the first empirical example of dominance reversal permitting greater optimisation of phenotypes within each sex, contributing to the resolution of sexual conflict in a major and widespread evolutionary trade-off between age and size at maturity. They also provide key empirical evidence for how variation in reproductive strategies can be maintained over large geographical scales. We further anticipate these findings will have a substantial impact on population management in a range of harvested species where trends towards earlier maturation have been observed

scholarly journals Intralocus sexual conflict and insecticide resistance

2016 ◽  
Vol 283 (1843) ◽  
pp. 20161429 ◽  
Author(s):  
M. F. Hawkes ◽  
C. E. Gamble ◽  
E. C. R. Turner ◽  
M. R. Carey ◽  
N. Wedell ◽  
...  
Keyword(s):  
Insecticide Resistance ◽  
Sexual Conflict ◽  
Balancing Selection ◽  
Population Level ◽  
Genetic Modifiers ◽  
P450 Gene ◽  
Individual Level ◽  
Intralocus Sexual Conflict ◽  
Fitness Effects ◽  
Investment In Reproduction

The BA allele of the Drosophila cytochrome P450 gene Cyp6g1 confers resistance to a range of insecticides. It is also subject to intralocus sexual conflict when introgressed into the Canton-S background, whose collection predates the widespread use of insecticides. In this genetic background, the allele confers a pleiotropic fitness benefit to females but a cost to males, and exhibits little sexual dimorphism in conferred insecticide resistance. It is unclear whether these sexually antagonistic effects also exist in current populations that have naturally evolved with insecticides, where genetic modifiers that offset male costs might be expected to evolve. Here, we explore these issues using Drosophila melanogaster caught recently from an Australian population in which the BA allele naturally segregates. While we find increased fecundity in insecticide-resistant BA females and no consistent evidence of fitness costs in males, experimental evolution indicates balancing selection at the locus. We suggest that this apparent discrepancy may be due to reduced investment in reproduction in resistant males. Our results at the population level are consistent with previous work, and suggest that individual-level fitness assays do not always capture sexually antagonistic fitness effects that emerge in a population context.

scholarly journals Sexual conflict over survival in Trinidadian Guppies

2021 ◽  
Author(s):  
Yuying Lin ◽  
Iulia Darolti ◽  
Benjamin L. S. Furman ◽  
Pedro Almeida ◽  
Benjamin A. Sandkam ◽  
...  
Keyword(s):  
Y Chromosome ◽  
Sexual Conflict ◽  
Balancing Selection ◽  
Fluctuating Selection ◽  
Allelic Differences ◽  
Show Evidence ◽  
Males And Females ◽  
Male Specific ◽  
Genetic Signatures ◽  
Allelic Differentiation

ABSTRACTSexual conflict over survival produces two distinct population genetic signatures. Fluctuating selection in males and females produces balancing selection. Additionally, at conception, allele frequencies are the same in males and females. However, loci with alleles that benefit the survival of one sex at some survival cost to the other should diverge over the course of a generation. We therefore expect that sexual conflict over survival would produce both signatures of allelic differentiation between the sexes and balancing selection. However, given the substantial mortality costs required to produce allelic differences between males and females, it remains unclear how many loci within the genome, if any at all, experience significant sexual conflict over survival. We assessed the genomes of 120 wild-caught guppies, which are expected to experience substantial predation- and pathogen-induced mortality. We identified a core list of 15 high confidence genes that show allelic differences between male and female adults. However, eight of these show evidence of having duplicated copies on the Y chromosome, suggesting that the male-specific region of the guppy Y chromosome may act as a hotspot for the resolution of conflict. We recovered just seven genes with significant male-female allelic differentiation without evidence of Y duplication, and these show elevated Tajima’s D, consistent with balancing selection from sexual conflict. Only one of these seven genes, Puf60b, shows substantial intersexual FST. Puf60b has roles in cognition and the immune system, suggesting substantial ongoing, unresolved sexual conflict related to predator and pathogen avoidance strategies.

scholarly journals Constraints on the coevolution of contemporary human males and females

2012 ◽  
Vol 279 (1748) ◽  
pp. 4836-4844 ◽  
Author(s):  
Stephen C. Stearns ◽  
Diddahally R. Govindaraju ◽  
Douglas Ewbank ◽  
Sean G. Byars
Keyword(s):  
Sexual Conflict ◽  
Age At First Birth ◽  
Male And Female ◽  
Selection Gradients ◽  
Intralocus Sexual Conflict ◽  
Individual Traits ◽  
Sexually Antagonistic Selection ◽  
Males And Females ◽  
Female Responses ◽  
Genetic Covariances

Because autosomal genes in sexually reproducing organisms spend on average half their time in each sex, and because the traits that they influence encounter different selection pressures in males and females, the evolutionary responses of one sex are constrained by processes occurring in the other sex. Although intralocus sexual conflict can restrict sexes from reaching their phenotypic optima, no direct evidence currently supports its operation in humans. Here, we show that the pattern of multivariate selection acting on human height, weight, blood pressure and glucose, total cholesterol, and age at first birth differs significantly between males and females, and that the angles between male and female linear (77.8 ± 20.5°) and nonlinear (99.1 ± 25.9°) selection gradients were closer to orthogonal than zero, confirming the presence of sexually antagonistic selection. We also found evidence for intralocus sexual conflict demonstrated by significant changes in the predicted male and female responses to selection of individual traits when cross-sex genetic covariances were included and a significant reduction in the angle between male- and female-predicted responses when cross-sex covariances were included (16.9 ± 15.7°), compared with when they were excluded (87.9 ± 31.6°). We conclude that intralocus sexual conflict constrains the joint evolutionary responses of the two sexes in a contemporary human population.

scholarly journals Parental sex discrimination and intralocus sexual conflict

2009 ◽  
Vol 5 (5) ◽  
pp. 667-670 ◽  
Author(s):  
Manus M. Patten ◽  
David Haig
Keyword(s):  
Maternal Effects ◽  
Sexual Conflict ◽  
Maternal Effect ◽  
Evolutionary Dynamics ◽  
Sex Discrimination ◽  
Sexual Antagonism ◽  
Natural Genetic Variation ◽  
Intralocus Sexual Conflict ◽  
Locus Model ◽  
Fitness Consequences

Intralocus sexual conflict occurs when populations segregate for alleles with opposing fitness consequences in the two sexes. This form of selection is known to be capable of maintaining genetic and fitness variation in nature, the extent of which is sensitive to the underlying genetics. We present a one-locus model of a haploid maternal effect that has sexually antagonistic consequences for offspring. The evolutionary dynamics of these maternal effects are distinct from those of haploid direct effects under sexual antagonism because the relevant genes are expressed only in females. Despite this, we find the same opportunity for sexually antagonistic polymorphism at the maternal effect locus as at a direct effect locus. Thus, sexually antagonistic maternal effects may underlie some natural genetic variation. The model we present permits alternative interpretations of how the genes are expressed and how the fitness variation is assigned, which invites a theoretical comparison to models of both imprinted genes and sex allocation.

scholarly journals Intralocus sexual conflict for fitness: sexually antagonistic alleles for testosterone

2011 ◽  
Vol 279 (1735) ◽  
pp. 1889-1895 ◽  
Author(s):  
Suzanne C. Mills ◽  
Esa Koskela ◽  
Tapio Mappes
Keyword(s):  
Negative Correlation ◽  
Sexual Conflict ◽  
Bank Vole ◽  
Genetic Locus ◽  
Myodes Glareolus ◽  
Phenotypic Traits ◽  
Intralocus Sexual Conflict ◽  
Opposite Sex ◽  
Sexually Antagonistic Selection ◽  
Males And Females

Intralocus sexual conflict occurs when a trait encoded by the same genetic locus in the two sexes has different optima in males and females. Such conflict is widespread across taxa, however, the shared phenotypic traits that mediate the conflict are largely unknown. We examined whether the sex hormone, testosterone (T), that controls sexual differentiation, contributes to sexually antagonistic fitness variation in the bank vole, Myodes glareolus . We compared (opposite-sex) sibling reproductive fitness in the bank vole after creating divergent selection lines for T. This study shows that selection for T was differentially associated with son versus daughter reproductive success, causing a negative correlation in fitness between full siblings. Our results demonstrate the presence of intralocus sexual conflict for fitness in this small mammal and that sexually antagonistic selection is acting on T. We also found a negative correlation in fitness between parents and their opposite-sex progeny (e.g. father–daughter), highlighting a dilemma for females, as the indirect genetic benefits of selecting reproductively successful males (high T) are lost with daughters. We discuss mechanisms that may mitigate this disparity between progeny quality.

scholarly journals Sex-Biased Gene Expression Resolves Sexual Conflict through the Evolution of Sex-Specific Genetic Architecture

2017 ◽  
Author(s):  
Alison E. Wright ◽  
Matteo Fumagalli ◽  
Christopher R. Cooney ◽  
Natasha I. Bloch ◽  
Filipe G. Vieira ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Sexual Conflict ◽  
Genetic Architecture ◽  
Balancing Selection ◽  
Genome Diversity ◽  
Regulatory Evolution ◽  
Novel Approach ◽  
Underlying Causes ◽  
Efficient Route ◽  
Males And Females

ABSTRACTMany genes are subject to contradictory selection pressures in males and females, and balancing selection resulting from sexual conflict has the potential to substantially increase standing genetic diversity in populations and thereby act as an important force in adaptation. However, the underlying causes of sexual conflict, and the potential for resolution, remains hotly debated. Using transcriptome resequencing data from male and female guppies, we use a novel approach, combining patterns of genetic diversity and inter-sexual divergence in allele frequency, to distinguish the different scenarios that give rise to sexual conflict, and how this conflict may be resolved through regulatory evolution. We show that reproductive fitness is the main source of sexual conflict, and this is resolved via the evolution of male-biased expression. Furthermore, resolution of sexual conflict produces significant differences in genetic architecture between males and females, which in turn leads to specific alleles influencing sex-specific viability. Together, our findings suggest an important role for sexual conflict in shaping broad patterns of genome diversity, and show that regulatory evolution is a rapid and efficient route to the resolution of conflict.

scholarly journals Sexes suffer from suboptimal lifespan because of genetic conflict in a seed beetle

2012 ◽  
Vol 279 (1745) ◽  
pp. 4296-4302 ◽  
Author(s):  
Elena C. Berg ◽  
Alexei A. Maklakov
Keyword(s):  
Callosobruchus Maculatus ◽  
Life History Evolution ◽  
Relative Fitness ◽  
Sexual Antagonism ◽  
Genetic Conflict ◽  
Intralocus Sexual Conflict ◽  
Research Programmes ◽  
Future Reproduction ◽  
Males And Females ◽  
Seed Beetles

Males and females have different routes to successful reproduction, resulting in sex differences in lifespan and age-specific allocation of reproductive effort. The trade-off between current and future reproduction is often resolved differently by males and females, and both sexes can be constrained in their ability to reach their sex-specific optima owing to intralocus sexual conflict. Such genetic antagonism may have profound implications for evolution, but its role in ageing and lifespan remains unresolved. We provide direct experimental evidence that males live longer and females live shorter than necessary to maximize their relative fitness in Callosobruchus maculatus seed beetles. Using artificial selection in a genetically heterogeneous population, we created replicate long-life lines where males lived on average 27 per cent longer than in short-life lines. As predicted by theory, subsequent assays revealed that upward selection on male lifespan decreased relative male fitness but increased relative female fitness compared with downward selection. Thus, we demonstrate that lifespan-extending genes can help one sex while harming the other. Our results show that sexual antagonism constrains adaptive life-history evolution, support a novel way of maintaining genetic variation for lifespan and argue for better integration of sex effects into applied research programmes aimed at lifespan extension.

Reproductive behavior

2018 ◽  
Author(s):  
Rachel Olzer ◽  
Rebecca L. Ehrlich ◽  
Justa L. Heinen-Kay ◽  
Jessie Tanner ◽  
Marlene Zuk
Keyword(s):  
Sexual Selection ◽  
Sexual Conflict ◽  
Female Choice ◽  
Reproductive Behavior ◽  
Mating Systems ◽  
Insect Behavior ◽  
Sequential Approach ◽  
Evolutionary Mechanisms ◽  
Anatomy And Physiology ◽  
Males And Females

Sex and reproduction lie at the heart of studies of insect behavior. We begin by providing a brief overview of insect anatomy and physiology, followed by an introduction to the overarching themes of parental investment, sexual selection, and mating systems. We then take a sequential approach to illustrate the diversity of phenomena and concepts behind insect reproductive behavior from pre-copulatory mate signalling through copulatory sperm transfer, mating positions, and sexual conflict, to post-copulatory sperm competition, and cryptic female choice. We provide an overview of the evolutionary mechanisms driving reproductive behavior. These events are linked by the economic defendability of mates or resources, and how these are allocated in each sex. Under the framework of economic defendability, the reader can better understand how sexual antagonistic behaviors arise as the result of competing optimal fitness strategies between males and females.

scholarly journals The cost of associating with males for Bornean and Sumatran female orangutans: a hidden form of sexual conflict?

2020 ◽  
Vol 75 (1) ◽  
Author(s):  
Julia A. Kunz ◽  
Guilhem J. Duvot ◽  
Maria A. van Noordwijk ◽  
Erik P. Willems ◽  
Manuela Townsend ◽  
...  
Keyword(s):  
Sexual Conflict ◽  
Sexual Coercion ◽  
High Association ◽  
Sexual Swellings ◽  
Fecal Cortisol ◽  
Habitat Productivity ◽  
Pongo Pygmaeus Wurmbii ◽  
Males And Females ◽  
Study Sites ◽  
The Cost

Abstract Sexual coercion, in the form of forced copulations, is relatively frequently observed in orangutans and generally attributed to their semi-solitary lifestyle. High ecological costs of association for females may be responsible for this lifestyle and may have prevented the evolution of morphological fertility indicators (e.g., sexual swellings), which would attract (male) associates. Therefore, sexual conflict may arise not only about mating per se but also about associations, because males may benefit from associations with females to monitor their reproductive state and attempt to monopolize their sexual activities. Here, we evaluate association patterns and costs for females when associating with both males and females of two different orangutan species at two study sites: Suaq, Sumatra (Pongo abelii), and Tuanan, Borneo (Pongo pygmaeus wurmbii). Female association frequency with both males and females was higher in the Sumatran population, living in more productive habitat. Accordingly, we found that the cost of association, in terms of reduced feeding to moving ratio and increased time being active, is higher in the less sociable Bornean population. Males generally initiated and maintained such costly associations with females, and prolonged associations with males led to increased female fecal cortisol metabolite (FCM) levels at Tuanan, the Bornean population. We conclude that male-maintained associations are an expression of sexual conflict in orangutans, at least at Tuanan. For females, this cost of association may be responsible for the lack of sexual signaling, while needing to confuse paternity. Significance statement Socioecological theory predicts a trade-off between the benefits of sociality and the ecological costs of increased feeding competition. Orangutans’ semi-solitary lifestyle has been attributed to the combination of high association costs and low predation risk. Previous work revealed a positive correlation between association frequencies and habitat productivity, but did not measure the costs of association. In this comparative study, we show that females likely incur costs from involuntary, male-maintained associations, especially when they last for several days and particularly in the population characterized by lower association frequencies. Association maintenance therefore qualifies as another expression of sexual conflict in orangutans, and especially prolonged, male-maintained associations may qualify as an indirect form of sexual coercion.

Variation within and between Rivers in Adult Size and Sea Age at Maturity of Anadromous Brown Trout, Salmo trutta

1991 ◽  
Vol 48 (6) ◽  
pp. 1015-1021 ◽  
Author(s):  
Jan Henning L'Abée-Lund
Keyword(s):  
Brown Trout ◽  
Sexual Maturity ◽  
Salmo Trutta ◽  
Adult Size ◽  
Age At Maturity ◽  
Migration Distance ◽  
Spawning Area ◽  
Brown Trout Salmo Trutta ◽  
Males And Females ◽  
The Mean

I compared adult size and sea age at sexual maturity among nine populations of anadromous brown trout, Salmo trutta, in two Norwegian rivers to determine the extent of inter- and intrariverine variations. Variation in the mean length of spawners and in the mean sea age at sexual maturity were mainly dependent on the variations found within rather than between rivers. Mean lengths and mean age at maturity of males increased significantly with increasing altitude of the spawning area and with migration distance in freshwater. In females, positive significant correlations were found with mean lengths and altitude of the spawning area and with mean sea age at maturity and both spawning site altitude and migration distance. Mean lengths and ages of males and females were not significantly correlated with the rate of water discharge in the streams during spawning. The size of gravel substrate for spawning was of minor importance in explaining interpopulation variation in mean female size. The increase noted in mean length and in mean sea age at maturity of both males and females is probably an adaptation to greater energy expenditure to reach the uppermost natal spawning areas.

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