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Sexual selection has minimal impact on effective population sizes in species with high rates of random offspring mortality: An empirical demonstration using fitness distributions
Author(s) -
Pischedda Alison,
Friberg Urban,
Stewart Andrew D.,
Miller Paige M.,
Rice William R.
Publication year - 2015
Publication title -
evolution
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.84
H-Index - 199
eISSN - 1558-5646
pISSN - 0014-3820
DOI - 10.1111/evo.12764
Subject(s) - biology , offspring , fecundity , selection (genetic algorithm) , population , sexual selection , reproductive success , effective population size , demography , genetic variation , evolutionary biology , genetics , pregnancy , artificial intelligence , sociology , computer science , gene
The effective population size ( N e ) is a fundamental parameter in population genetics that influences the rate of loss of genetic diversity. Sexual selection has the potential to reduce N e by causing the sex‐specific distributions of individuals that successfully reproduce to diverge. To empirically estimate the effect of sexual selection on N e , we obtained fitness distributions for males and females from an outbred, laboratory‐adapted population of Drosophila melanogaster . We observed strong sexual selection in this population (the variance in male reproductive success was ∼14 times higher than that for females), but found that sexual selection had only a modest effect on N e , which was 75% of the census size. This occurs because the substantial random offspring mortality in this population diminishes the effects of sexual selection on N e , a result that necessarily applies to other high fecundity species. The inclusion of this random offspring mortality creates a scaling effect that reduces the variance/mean ratios for male and female reproductive success and causes them to converge. Our results demonstrate that measuring reproductive success without considering offspring mortality can underestimate N e and overestimate the genetic consequences of sexual selection. Similarly, comparing genetic diversity among different genomic components may fail to detect strong sexual selection.