scholarly journals Imminent risk of predation reduces the relative strength of postcopulatory sexual selection in the guppy

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200076
Author(s):  
Alexandra Glavaschi ◽  
Silvia Cattelan ◽  
Alessandro Grapputo ◽  
Andrea Pilastro
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Repeated Measures ◽  
Poecilia Reticulata ◽  
Male Reproductive Success ◽  
Sperm Production ◽  
Postcopulatory Sexual Selection ◽  
Repeated Measures Design ◽  
Risk Of Predation ◽  
Livebearing Fish

Fifty years of research on sperm competition has led to a very good understanding of the interspecific variation in sperm production traits. The reasons why this variation is often very large within populations have been less investigated. We suggest that the interaction between fluctuating environmental conditions and polyandry is a key phenomenon explaining such variation. We focus here on imminent predation risk (IPR). IPR impacts significantly several aspects of prey behaviour and reproduction, and it is expected to influence the operation of sexual selection before and after mating. We estimated the effect of IPR on the male opportunity for pre- and postcopulatory sexual selection in guppies ( Poecilia reticulata ), a livebearing fish where females prefer colourful males and mate multiply. We used a repeated-measures design, in which males were allowed to mate with different females either under IPR or in a predator-free condition. We found that IPR increased the total opportunity for sexual selection and reduced the relative contribution of postcopulatory sexual selection to male reproductive success. IPR is inherently variable and our results suggest that interspecific reproductive interference by predators may contribute towards maintaining the variation in sperm production within populations. This article is part of the theme issue ‘Fifty years of sperm competition'.

scholarly journals Female control over multiple matings increases the opportunity for postcopulatory sexual selection

2018 ◽  
Vol 285 (1888) ◽  
pp. 20181505 ◽  
Author(s):  
Clelia Gasparini ◽  
Jonathan P. Evans
Keyword(s):  
Sexual Selection ◽  
Poecilia Reticulata ◽  
Critical Role ◽  
Reproductive Fitness ◽  
Behavioural Control ◽  
Male Reproductive Success ◽  
Postcopulatory Sexual Selection ◽  
Full Control ◽  
Quantitative Understanding ◽  
Paired Design

It is widely acknowledged that in most species sexual selection continues after mating. Although it is generally accepted that females play an important role in generating paternity biases (i.e. cryptic female choice, CFC), we lack a quantitative understanding of the relative importance of female-controlled processes in influencing variance in male reproductive fitness. Here, we address this question experimentally using the guppy Poecilia reticulata , a polyandrous fish in which pre- and postcopulatory sexual selection jointly determine male reproductive fitness. We used a paired design to quantify patterns of paternity for pairs of rival males across two mating contexts, one in which the female retained full control over double (natural) matings and one where sperm from the same two males were artificially inseminated into the female. We then compared the relative paternity share for a given pair of males across both contexts, enabling us to test the key prediction that patterns of paternity will depend on the extent to which females retain behavioural control over matings. As predicted, we found stronger paternity biases when females retained full control over mating compared with when artificial insemination (AI) was used. Concomitantly, we show that the opportunity for postcopulatory sexual selection (standardized variance in male reproductive success) was greater when females retained control over double matings compared with when AI was used. Finally, we show that the paternity success of individual males exhibited higher repeatability across successive brood cycles when females retained behavioural control of matings compared with when AI was used. Collectively, these findings underscore the critical role that females play in determining the outcome of sexual selection and to our knowledge provide the first experimental evidence that behaviourally moderated components of CFC increase the opportunity for sexual selection.

scholarly journals Multivariate selection drives concordant patterns of pre- and postcopulatory sexual selection in a livebearing fish

2015 ◽  
Vol 6 (1) ◽  
Author(s):  
Alessandro Devigili ◽  
Jonathan P. Evans ◽  
Andrea Di Nisio ◽  
Andrea Pilastro
Keyword(s):  
Sexual Selection ◽  
Postcopulatory Sexual Selection ◽  
Livebearing Fish

scholarly journals Sexual selection and ageing: interplay between pre- and post-copulatory traits senescence in the guppy

2019 ◽  
Vol 286 (1897) ◽  
pp. 20182873 ◽  
Author(s):  
Clelia Gasparini ◽  
Alessandro Devigili ◽  
Andrea Pilastro
Keyword(s):  
Sexual Selection ◽  
Mating Systems ◽  
Poecilia Reticulata ◽  
Empirical Studies ◽  
Fertilization Success ◽  
Sperm Storage ◽  
Limited Information ◽  
Senescence Rate ◽  
Sexual Traits ◽  
Livebearing Fish

Traits associated with mating and fertilization success are expected to senesce with age, but limited information is available on their relative rates of senescence. In polyandrous species, male reproductive fitness depends on both mating and fertilization success. Because successful mating is a prerequisite for post-copulatory sexual selection, ejaculate traits are expected to senesce faster than pre-copulatory traits, as pre-copulatory sexual selection is often deemed to be stronger than post-copulatory sexual selection. This pattern has generally been found in the few empirical studies conducted so far. We tested this prediction in the guppy ( Poecilia reticulata ), a livebearing fish characterized by intense sperm competition, by comparing the expression of male sexual traits at two ages (four and nine months). Contrary to prediction, we found that post-copulatory traits senesced at a significantly slower rate than pre-copulatory traits. We also looked at whether early investment in those sexual traits affects longevity, and the interaction between sperm age (duration of sperm storage inside the male) and male age. Our results suggest that the relative senescence rate of pre- and post-copulatory sexual traits may vary among species with different mating systems and ecology.

scholarly journals Within-population sperm competition intensity does not predict asymmetry in conpopulation sperm precedence

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200071 ◽  
Author(s):  
Martin D. Garlovsky ◽  
Leeban H. Yusuf ◽  
Michael G. Ritchie ◽  
Rhonda R. Snook
Keyword(s):  
Sexual Selection ◽  
Gene Flow ◽  
Sperm Competition ◽  
Reproductive Tract ◽  
Fertilization Success ◽  
Female Reproductive Tract ◽  
Sperm Precedence ◽  
Arms Races ◽  
Postcopulatory Sexual Selection ◽  
The Face

Postcopulatory sexual selection can generate evolutionary arms races between the sexes resulting in the rapid coevolution of reproductive phenotypes. As traits affecting fertilization success diverge between populations, postmating prezygotic (PMPZ) barriers to gene flow may evolve. Conspecific sperm precedence is a form of PMPZ isolation thought to evolve early during speciation yet has mostly been studied between species. Here , we show conpopulation sperm precedence (CpSP) between Drosophila montana populations. Using Pool-seq genomic data we estimate divergence times and ask whether PMPZ isolation evolved in the face of gene flow. We find models incorporating gene flow fit the data best indicating populations experienced considerable gene flow during divergence. We find CpSP is asymmetric and mirrors asymmetry in non-competitive PMPZ isolation, suggesting these phenomena have a shared mechanism. However, we show asymmetry is unrelated to the strength of postcopulatory sexual selection acting within populations. We tested whether overlapping foreign and coevolved ejaculates within the female reproductive tract altered fertilization success but found no effect. Our results show that neither time since divergence nor sperm competitiveness predicts the strength of PMPZ isolation. We suggest that instead cryptic female choice or mutation-order divergence may drive divergence of postcopulatory phenotypes resulting in PMPZ isolation. This article is part of the theme issue ‘Fifty years of sperm competition’.

scholarly journals Sperm competition as an under-appreciated factor in domestication

2018 ◽  
Vol 14 (3) ◽  
pp. 20180043 ◽  
Author(s):  
Ardern Hulme-Beaman ◽  
Jeremy B. Searle ◽  
Paula Stockley
Keyword(s):  
Sexual Selection ◽  
Gene Flow ◽  
Sperm Competition ◽  
Mating Behaviour ◽  
Domestic Animals ◽  
Postcopulatory Sexual Selection ◽  
Selective Pressures ◽  
General Potential ◽  
Domestication Process

Humans created an environment that increased selective pressures on subgroups of those species that became domestic. We propose that the domestication process may in some cases have been facilitated by changes in mating behaviour and resultant sperm competition. By adapting to sperm competition, proto-domestic animals could potentially have outcompeted their wild counterparts in human-constructed niches. This could have contributed to the restriction of gene flow between the proto-domesticates and their wild counterparts, thereby promoting the fixation of other domestication characteristics. Further to this novel perspective for domestication, we emphasize the general potential of postcopulatory sexual selection in the restriction of gene flow between populations, and urge more studies.

scholarly journals The Drosophila seminal proteome and its role in postcopulatory sexual selection

2020 ◽  
Vol 375 (1813) ◽  
pp. 20200072 ◽  
Author(s):  
Stuart Wigby ◽  
Nora C. Brown ◽  
Sarah E. Allen ◽  
Snigdha Misra ◽  
Jessica L. Sitnik ◽  
...  
Keyword(s):  
Sexual Selection ◽  
Sperm Competition ◽  
Seminal Fluid ◽  
Current Knowledge ◽  
Future Research ◽  
Seminal Fluid Proteins ◽  
Scale Functions ◽  
Postcopulatory Sexual Selection ◽  
Evolutionary Force ◽  
Protein Classes

Postcopulatory sexual selection (PCSS), comprised of sperm competition and cryptic female choice, has emerged as a widespread evolutionary force among polyandrous animals. There is abundant evidence that PCSS can shape the evolution of sperm. However, sperm are not the whole story: they are accompanied by seminal fluid substances that play many roles, including influencing PCSS. Foremost among seminal fluid models is Drosophila melanogaster , which displays ubiquitous polyandry, and exhibits intraspecific variation in a number of seminal fluid proteins (Sfps) that appear to modulate paternity share. Here, we first consolidate current information on the identities of D. melanogaster Sfps. Comparing between D. melanogaster and human seminal proteomes, we find evidence of similarities between many protein classes and individual proteins, including some D. melanogaster Sfp genes linked to PCSS, suggesting evolutionary conservation of broad-scale functions. We then review experimental evidence for the functions of D. melanogaster Sfps in PCSS and sexual conflict. We identify gaps in our current knowledge and areas for future research, including an enhanced identification of PCSS-related Sfps, their interactions with rival sperm and with females, the role of qualitative changes in Sfps and mechanisms of ejaculate tailoring. This article is part of the theme issue ‘Fifty years of sperm competition’.

scholarly journals Male success against con- and heterospecific competitors indicates a positive but modest role for sexual selection as driver of speciation

2017 ◽  
Author(s):  
Jeremy S. Davis ◽  
Leonie C. Moyle
Keyword(s):  
Sexual Selection ◽  
Reproductive Success ◽  
Reproductive Isolation ◽  
Sperm Competition ◽  
Necessary Condition ◽  
Male Reproductive Success ◽  
Explicit Test ◽  
Underlying Mechanisms ◽  
The Relationship ◽  
Lines Of Evidence

AbstractFor sexual selection within species to drive the evolution of reproductive isolation between lineages, sexually selected and reproductive isolating traits must both share underlying mechanisms and operate in the same direction. While some work has been done to evaluate mechanistic overlap, fewer studies have evaluated whether intraspecific sexually-selected variation is associated with elevated reproductive isolation between species. Here we evaluate this association by assessing the relationship between male reproductive success against conspecifics versus heterospecific males at each of two different mating stages. We find that male precopulatory performance (remating success following a conspecific versus a heterospecific first mating) was not associated between conspecific and heterospecific contexts, but postcopulatory success (sperm competition against conspecific versus heterospecific males) was modestly positively correlated. We discuss two lines of evidence that suggest this modest association is due to incomplete mechanistic overlap between postcopulatory competition in conspecific and heterospecific mating contexts. This study provides an explicit test of a necessary condition for sexual selection to drive speciation, and finds that while sexual selection is not individually sufficient to explain the magnitude of reproductive isolation in this system, it could nonetheless facilitate the evolution of isolation via postcopulatory sperm competition.

Power of Modified Brown-Forsythe and Mixed-Model Approaches in Split-Plot Designs

Methodology ◽  
2017 ◽  
Vol 13 (1) ◽  
pp. 9-22 ◽  
Author(s):  
Pablo Livacic-Rojas ◽  
Guillermo Vallejo ◽  
Paula Fernández ◽  
Ellián Tuero-Herrero
Keyword(s):  
Repeated Measures ◽  
Statistical Power ◽  
Mixed Model ◽  
Covariance Structure ◽  
Simulation Method ◽  
Future Research ◽  
Repeated Measures Design ◽  
Fixed And Random Effects ◽  
Split Plot ◽  
High Level

Abstract. Low precision of the inferences of data analyzed with univariate or multivariate models of the Analysis of Variance (ANOVA) in repeated-measures design is associated to the absence of normality distribution of data, nonspherical covariance structures and free variation of the variance and covariance, the lack of knowledge of the error structure underlying the data, and the wrong choice of covariance structure from different selectors. In this study, levels of statistical power presented the Modified Brown Forsythe (MBF) and two procedures with the Mixed-Model Approaches (the Akaike’s Criterion, the Correctly Identified Model [CIM]) are compared. The data were analyzed using Monte Carlo simulation method with the statistical package SAS 9.2, a split-plot design, and considering six manipulated variables. The results show that the procedures exhibit high statistical power levels for within and interactional effects, and moderate and low levels for the between-groups effects under the different conditions analyzed. For the latter, only the Modified Brown Forsythe shows high level of power mainly for groups with 30 cases and Unstructured (UN) and Autoregressive Heterogeneity (ARH) matrices. For this reason, we recommend using this procedure since it exhibits higher levels of power for all effects and does not require a matrix type that underlies the structure of the data. Future research needs to be done in order to compare the power with corrected selectors using single-level and multilevel designs for fixed and random effects.

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