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

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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Long-term Exposure to Predation Threat Can Modulate the Expression of Sexually Selected Traits in Male Guppy (Poecilia reticulata)

Turkish Journal of Fisheries and Aquatic Sciences ◽

10.4194/1303-2712-v21_7_05 ◽

2021 ◽

Vol 21 (07) ◽

pp. 357-364

Author(s):

Md. Moshiur Rahman ◽

Prianka Biswas ◽

Sazzad Hossain ◽

Sheikh Mustafizur Rahman ◽

Ahmed Saud Alsaqufi ◽

...

Keyword(s):

Predation Risk ◽

Poecilia Reticulata ◽

Courtship Behavior ◽

Color Patterns ◽

Predation Threat ◽

Natural Systems ◽

Sexually Selected Traits ◽

Selected Traits ◽

Costly Traits ◽

Behavioral Trials

The expression of sexual traits can be affected by different environmental factors among which predation may be particularly important life-history traits. This study investigated the effects of predation risk on courtship behavior, growth and sexual color patterns in male guppy (Poecilia reticulata). In the study, juvenile male guppies were randomly assigned to two treatments, namely T1 (predation threat) and T2 (no predation threat). The courtship performances were visually observed and recorded, while color patterns and morphological traits were measured by using the ImageJ software from the captured photos. The courtship behavioral trials revealed that predation threatened males performed significantly lower number of sigmoid displays than those of no-predation group. Further, the predation scared group had significantly shorter standard length, body area and a reduced number and area of orange spots than their counter group. However, the predation threat did not affect significantly the gonopodial thrusts, and black and iridescent color components (spot number and area). The reduction of costly traits (e.g. behavior, color patterns and body size) is common anti-predator response which presumably reduces predation risks. Male guppies are probably using this form of defence in response to the increased predation risk. The overall result suggests that growth and sexually selected trait expression are sensitive to predation risk and thereby aid in our understanding to predict the evolution of phenotypic variation in natural systems.

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The causes and consequences of ornament variation in a natural population

10.32942/osf.io/89h65 ◽

2019 ◽

Author(s):

Annabel Ralph ◽

Terry Burke ◽

Shinichi Nakagawa ◽

Alfredo Sánchez-Tójar ◽

Julia Schroeder

Keyword(s):

Sexual Selection ◽

Evolutionary Biology ◽

Natural Populations ◽

Size Variation ◽

Evolutionary Potential ◽

House Sparrows ◽

Sexually Selected Traits ◽

Evolutionary Response ◽

Significant Heritability ◽

Selected Traits

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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Effect of induced mutations on sexually selected traits in the guppy, Poecilia reticulata

Animal Behaviour ◽

10.1016/j.anbehav.2015.09.013 ◽

2015 ◽

Vol 110 ◽

pp. 105-111 ◽

Cited By ~ 4

Author(s):

Magdalena Herdegen ◽

Jacek Radwan

Keyword(s):

Poecilia Reticulata ◽

Induced Mutations ◽

Sexually Selected Traits ◽

Selected Traits

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Short-term change in male sexually selected traits and female mate preference in the guppy Poecilia reticulata

Ichthyological Research ◽

10.1007/s10228-011-0239-x ◽

2011 ◽

Vol 59 (1) ◽

pp. 1-7 ◽

Cited By ~ 8

Author(s):

Hiromi Kudo ◽

Kenji Karino

Keyword(s):

Poecilia Reticulata ◽

Mate Preference ◽

Short Term ◽

Female Mate Preference ◽

Female Mate ◽

Sexually Selected Traits ◽

Short Term Change ◽

Term Change ◽

Selected Traits

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Sex ratio dynamics and fluctuating selection pressures in natural populations of the Trinidadian guppy, Poecilia reticulata

Behavioral Ecology and Sociobiology ◽

10.1007/s00265-003-0727-8 ◽

2004 ◽

Vol 55 (5) ◽

pp. 461-468 ◽

Cited By ~ 68

Author(s):

Lars B. Pettersson ◽

Indar W. Ramnarine ◽

S. Anette Becher ◽

Rajindra Mahabir ◽

Anne E. Magurran

Keyword(s):

Sex Ratio ◽

Poecilia Reticulata ◽

Natural Populations ◽

Fluctuating Selection ◽

Selection Pressures ◽

Trinidadian Guppy

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Fluctuating selection strength and intense male competition underlie variation and exaggeration of a water strider’s male weapon

10.1101/430314 ◽

2018 ◽

Author(s):

William Toubiana ◽

Abderrahman Khila

Keyword(s):

Mating Behavior ◽

Phenotypic Variation ◽

Male Competition ◽

Egg Laying ◽

Leg Length ◽

Fluctuating Selection ◽

Sexually Selected Traits ◽

Selected Traits ◽

Gravid Females ◽

The Impact

AbstractSexually selected traits can reach high degrees of expression and variation under directional selection. A growing number of studies suggest that such selection can vary in space, time and form within and between populations. However, the impact of these fluctuations on sexual trait expression is poorly understood. The water striderMicrovelia longipesdisplays a striking case of exaggeration and phenotypic variation where males display extreme differences in the size of their rear legs. To study the origin and maintenance of this exaggerated trait, we conducted comparative behavioral and morphometric experiments in a sample ofMicroveliaspecies. We uncovered differences both in the mating behavior and the degree of sexual dimorphism across these species. Interestingly,M. longipesevolved a specific mating behavior where males compete for egg-laying sites, consisting of small floating objects, to intercept and copulate with gravid females. Field observations revealed rapid fluctuation inM. longipeshabitat stability and the abundance of egg-laying sites. Through male-male competition assays, we demonstrated that male rear legs are used as weapons to dominate egg-laying sites and that intense competition is associated with the evolution of rear leg length exaggeration. Paternity tests using genetic markers demonstrated that small males could only fertilize about 5% of the eggs when egg-laying sites are limiting, whereas this proportion increased to about 20% when egg-laying sites become abundant. Furthermore, diet manipulation and artificial selection experiments also showed that the exaggerated leg length inM. longipesmales is influenced by both genetic and nutritional factors. Collectively, our results highlight how fluctuation in the strength of directional sexual selection, through changes in the intensity of male competition, can drive the exaggeration and phenotypic variation in this weapon trait.

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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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