Does differential mortality after parental investment affect sex ratio evolution? No

Research output: Contribution to journalArticlepeer-review

Abstract

The classical view of sex ratio evolution, popularized by R. A. Fisher, is that the sex ratio at birth should be equal when males and females require the same level of parental investment. Thus, although differences in mortality between the sexes during parental investment will cause deviations from an equal sex ratio at birth, differential mortality after parental investment should have no effect. However, a recent theoretical model appears to contradict this view, suggesting that differential mortality after the period of parental investment does cause deviations from an equal sex ratio at birth. Moreover, the life stage at which mortality differs (juvenile vs. adult) is predicted to cause contrasting effects on sex ratio evolution. These results are in stark contrast with Fisher's hypothesis. Here, we resolve this disparity by analyzing a stage- and sex- structured model of population dynamics. We find that selection always drives the population to an equal sex ratio at birth regardless of differential mortality effects after parental investment, thus confirming Fisher's hypothesis. The disparity appears to be due to incorrect accounting of mutant-resident unions, which we avoid by considering separate union classes for different types of mutant-resident unions.

Original languageEnglish
Pages (from-to)3175-3180
JournalEvolution
Volume75
Issue number12
Early online date11 Oct 2021
DOIs
Publication statusPublished - 1 Dec 2021

Keywords

  • Adult
  • age structure
  • evolution
  • juvenile
  • mortality
  • sex ratio

ASJC Scopus subject areas

  • Ecology, Evolution, Behavior and Systematics
  • Genetics
  • Agricultural and Biological Sciences(all)

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