The genetic architecture of sexually selected traits in two natural populations of Drosophila montana

The role of sexual selection in natural populations has long been the subject of debate in evolutionary biology. Ornaments are sexually selected traits, which means they should vary within a population, have a genetic basis, and be associated with fitness. Despite evidence of ornaments meeting these criteria, evolutionary responses to sexual selection are rare in nature. This study focuses on two ornaments in a population of house sparrows; the plumage badge has been well-studied but remains poorly understood and the mask has been largely neglected in the literature. Using quantitative genetic techniques, we estimate the heritability of both traits and test for age-dependency of the heritability estimates. We also estimate the strength and direction of any selection acting upon the traits. We found that both ornaments have low, significant heritability, which does not vary with age. Selection only occurs in a small number of years, although when it does it is positive in both ornaments. We also found that early social environment plays a role in badge size variation. The results of this study suggest that an evolutionary response in the ornaments of this population is unlikely, but we highlight the importance of long-term research to improve our understanding of evolution in natural populations. Studies like these will add to our understanding of sexual selection, the causes of trait variation and the evolutionary potential of traits, which could help us to predict how populations will evolve.

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Geographical variation in the male intromittent organ of the Trinidadian guppy (Poecilia reticulata)

Canadian Journal of Zoology ◽

10.1139/z00-080 ◽

2000 ◽

Vol 78 (9) ◽

pp. 1674-1680 ◽

Cited By ~ 23

Author(s):

Clint D Kelly ◽

Jean-Guy J Godin ◽

Ghada Abdallah

Keyword(s):

Phenotypic Variation ◽

Poecilia Reticulata ◽

Natural Populations ◽

Fish Predation ◽

Species Variation ◽

Body Coloration ◽

Sexually Selected Traits ◽

Predation Intensity ◽

Trinidadian Guppy ◽

Selected Traits

Sexual selection may favour the evolution of elaborated genital traits in males, particularly when phenotypic variation in such traits results in corresponding variation in reproductive success among males in the population. Compared with insects, very little is known about the natural variation in any male genital trait, and its causes, in vertebrates. Here we report on variation in a male intromittent organ both within and between natural populations of a vertebrate, the Trinidadian guppy (Poecilia reticulata). Male guppies inseminate females using an intromittent organ called the gonopodium. We demonstrate that males from populations that have evolved under high fish-predation intensity have, on average, a relatively longer gonopodium than males originating from populations under low fish-predation intensity. Compared with body coloration, the gonopodium exhibited relatively low phenotypic variation, but nonetheless was within the range of known variation for sexually selected traits. The male gonopodium was positively allometric in general. To our knowledge, this is the first report of within-species variation in an intromittent organ and of a positive allometric relationship between male genitalia and body size in a vertebrate species. Our results suggest that the length of the male intromittent organ in the guppy is under selection, which varies geographically.

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Evolutionary rates for multivariate traits: the role of selection and genetic variation

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2013.0252 ◽

2014 ◽

Vol 369 (1649) ◽

pp. 20130252 ◽

Cited By ~ 28

Author(s):

William Pitchers ◽

Jason B. Wolf ◽

Tom Tregenza ◽

John Hunt ◽

Ian Dworkin

Keyword(s):

Evolutionary Biology ◽

Genetic Architecture ◽

Genetic Variance ◽

Evolutionary Rates ◽

Phenotypic Traits ◽

Sexually Selected Traits ◽

Rates Of Evolution ◽

Selected Traits ◽

Multivariate Traits

A fundamental question in evolutionary biology is the relative importance of selection and genetic architecture in determining evolutionary rates. Adaptive evolution can be described by the multivariate breeders' equation ( ), which predicts evolutionary change for a suite of phenotypic traits ( ) as a product of directional selection acting on them ( β ) and the genetic variance–covariance matrix for those traits ( G ). Despite being empirically challenging to estimate, there are enough published estimates of G and β to allow for synthesis of general patterns across species. We use published estimates to test the hypotheses that there are systematic differences in the rate of evolution among trait types, and that these differences are, in part, due to genetic architecture. We find some evidence that sexually selected traits exhibit faster rates of evolution compared with life-history or morphological traits. This difference does not appear to be related to stronger selection on sexually selected traits. Using numerous proposed approaches to quantifying the shape, size and structure of G , we examine how these parameters relate to one another, and how they vary among taxonomic and trait groupings. Despite considerable variation, they do not explain the observed differences in evolutionary rates.

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Genomic analysis reveals a polygenic architecture of antler morphology in wild red deer (Cervus elaphus)

10.1101/2021.04.16.440189 ◽

2021 ◽

Author(s):

Lucy Peters ◽

Jisca Huisman ◽

Loeske E.B. Kruuk ◽

Josephine M. Pemberton ◽

Susan E. Johnston

Keyword(s):

Genetic Variation ◽

Cervus Elaphus ◽

Genetic Architecture ◽

Empirical Bayes ◽

Red Deer ◽

Genetic Correlations ◽

Rapid Evolution ◽

Genomic Analysis ◽

Sexually Selected Traits ◽

Selected Traits

AbstractSexually-selected traits show large variation and rapid evolution across the animal kingdom, yet genetic variation often persists within populations despite apparent directional selection. A key step in solving this long-standing paradox is to determine the genetic architecture of sexually-selected traits to understand evolutionary drivers and constraints at the genomic level. Antlers are a form of sexual weaponry in male red deer. On the island of Rum, Scotland, males with larger antlers have increased breeding success, yet there has been no response to selection observed at the genetic level. To better understand the underlying mechanisms of this observation, we investigate the genetic architecture of ten antler traits and their principle components using genomic data from >38,000 SNPs. We estimate the heritabilities and genetic correlations of the antler traits using a genomic relatedness approach. We then use genome-wide association and haplotype-based regional heritability to identify regions of the genome underlying antler morphology, and an Empirical Bayes approach to estimate the underlying distributions of allele effect sizes. We show that antler morphology is heritable with a polygenic architecture, highly repeatable over an individual’s lifetime, and that almost all aspects are positively genetically correlated with some loci identified as having pleiotropic effects. Our findings suggest that a large mutational target and pleiotropy with traits sharing similar complex polygenic architectures are likely to contribute to the maintenance of genetic variation in antler morphology in this population.

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Characterizing the evolution of genetic variance using genetic covariance tensors

Philosophical Transactions of the Royal Society B Biological Sciences ◽

10.1098/rstb.2008.0313 ◽

2009 ◽

Vol 364 (1523) ◽

pp. 1567-1578 ◽

Cited By ~ 58

Author(s):

Emma Hine ◽

Stephen F. Chenoweth ◽

Howard D. Rundle ◽

Mark W. Blows

Keyword(s):

Genetic Variance ◽

Natural Populations ◽

Covariance Structure ◽

Evolutionary Genetics ◽

Geometric Framework ◽

Genetic Covariance ◽

Sexually Selected Traits ◽

Selected Traits ◽

Higher Order Tensors ◽

The Individual

Determining how genetic variance changes under selection in natural populations has proved to be a very resilient problem in evolutionary genetics. In the same way that understanding the availability of genetic variance within populations requires the simultaneous consideration of genetic variance in sets of functionally related traits, determining how genetic variance changes under selection in natural populations will require ascertaining how genetic variance–covariance ( G ) matrices evolve. Here, we develop a geometric framework using higher-order tensors, which enables the empirical characterization of how G matrices have diverged among populations. We then show how divergence among populations in genetic covariance structure can then be associated with divergence in selection acting on those traits using key equations from evolutionary theory. Using estimates of G matrices of eight male sexually selected traits from nine geographical populations of Drosophila serrata , we show that much of the divergence in genetic variance occurred in a single trait combination, a conclusion that could not have been reached by examining variation among the individual elements of the nine G matrices. Divergence in G was primarily in the direction of the major axes of genetic variance within populations, suggesting that genetic drift may be a major cause of divergence in genetic variance among these populations.

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Evolutionary rates for multivariate traits: the role of selection and genetic variation

10.1101/002683 ◽

2014 ◽

Cited By ~ 2

Author(s):

William Pitchers ◽

Jason B. Wolf ◽

Tom Tregenza ◽

John Hunt ◽

Ian Dworkin

Keyword(s):

Evolutionary Biology ◽

Genetic Architecture ◽

Genetic Variance ◽

Evolutionary Rates ◽

Phenotypic Traits ◽

Sexually Selected Traits ◽

Rates Of Evolution ◽

Selected Traits ◽

Multivariate Traits

A fundamental question in evolutionary biology is the relative importance of selection and genetic architecture in determining evolutionary rates. Adaptive evolution can be described by the multivariate breeders' equation (Δz = Gβ), which predicts evolutionary change for a suite of phenotypic traits (Δz) as a product of directional selection acting on them (β) and the genetic variance-covariance matrix for those traits (G). Despite being empirically challenging to estimate, there are enough published estimates ofGandβto allow for synthesis of general patterns across species. We use published estimates to test the hypotheses that there are systematic differences in the rate of evolution among trait types, and that these differences are in part due to genetic architecture. We find evidence that sexually selected traits exhibit faster rates of evolution compared to life-history or morphological traits. This difference does not appear to be related to stronger selection on sexually selected traits. Using numerous proposed approaches to quantifying the shape, size and structure ofGwe examine how these parameters relate to one another, and how they vary among taxonomic and trait groupings. Despite considerable variation, they do not explain the observed differences in evolutionary rates.

Download Full-text