Fitness effects of the timing of hatching may drive the evolution of temperature-dependent sex determination in short-lived lizards

Daniel A. Warner, Tobias Uller, Richard Shine

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

In several species of short-lived Australian agamid lizards, an individual's sex is determined by the nest temperatures encountered during incubation. The adaptive significance of such systems remains unclear. Here, we explore the hypothesis that (1) the optimal timing of hatching differs between the sexes, and thus (2) temperature-dependent sex determination (TSD) enhances maternal and offspring fitness by generating seasonal shifts in offspring sex ratios. Our model predicts that TSD can indeed enhance maternal fitness returns in short-lived lizards if (1) male-male competition is intense, thus reducing mating success of newly-matured males (but not females), and (2) the nesting season is prolonged, such that seasonal effects become significant. Available data on the distribution of TSD in Australian agamid lizards broadly support these predictions. Because both the level of male-male competition and the length of nesting season can vary at small spatial and temporal scales, selective forces on sex-determining mechanisms also should vary. Hence, our model predicts extensive small-scale (intraspecific) variation in sex-determining systems within agamid lizards, as well as among species.

Original languageEnglish
Article number281
Pages (from-to)281-294
Number of pages14
JournalEvolutionary Ecology
Volume23
Issue number2
DOIs
Publication statusPublished - Mar 2009
Externally publishedYes

Keywords

  • agamidae
  • Charnov-Bull model
  • environmental sex determination
  • genotypic sex determination
  • male-male competition
  • sex ratio theory

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