biostudies-literatureKasimatis KRnatural sciences and engineering research council of canadanational institutes of healthNIGMS NIH HHSe1010063https://www.ebi.ac.uk/biostudies/studies/S-EPMC8880957biostudies-literatureUnknown18(2)Sexual reproduction is a complex process that contributes to differences between the sexes and divergence between species. From a male's perspective, sexual selection can optimize reproductive success by acting on the variance in mating success (pre-insemination selection) as well as the variance in fertilization success (post-insemination selection). The balance between pre- and post-insemination selection has not yet been investigated using a strong hypothesis-testing framework that directly quantifies the effects of post-insemination selection on the evolution of reproductive success. Here we use experimental evolution of a uniquely engineered genetic system that allows sperm production to be turned off and on in obligate male-female populations of Caenorhabditis elegans. We show that ePLoS geneticsPost-insemination selection dominates pre-insemination selection in driving rapid evolution of male competitive ability.PMC8880957Banting Postdoctoral FellowshipR35GM131838R35 GM131838Moerdyk-Schauwecker MJPhillips PCKasimatis KRLancaster RSmith AWillis JHfalsePost-insemination selection dominates pre-insemination selection in driving rapid evolution of male competitive ability.Sexual reproduction is a complex process that contributes to differences between the sexes and divergence between species. From a male's perspective, sexual selection can optimize reproductive success by acting on the variance in mating success (pre-insemination selection) as well as the variance in fertilization success (post-insemination selection). The balance between pre- and post-insemination selection has not yet been investigated using a strong hypothesis-testing framework that directly quantifies the effects of post-insemination selection on the evolution of reproductive success. Here we use experimental evolution of a uniquely engineered genetic system that allows sperm production to be turned off and on in obligate male-female populations of Caenorhabditis elegans. We show that e2022-01-01T00:00:00Z2022 Feb2025-04-25T22:31:16.211Z2025-04-06T09:04:37.372ZS-EPMC88809573515771710.1371/journal.pgen.1010063