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Updated: Jun 16, 2026
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Published on: February 7, 2019
Are reptiles predisposed to temperature-dependent sex determination?
1Institute for Applied Ecology, University of Canberra, Canberra, ACT, Australia. georges @ aerg.canberra.edu.au
Summary
Reptiles may evolve temperature-dependent sex determination (TSD) due to variable embryonic environments. This predisposition, arising from genotypic sex determination (GSD), allows natural selection to favor TSD when advantageous.
Area of Science:
- Evolutionary biology
- Developmental biology
- Herpetology
Background:
- Vertebrates exhibit diverse sex determination mechanisms.
- Mammalian and avian sex determination are highly conserved.
- Reptilian sex determination is notably variable.
Purpose of the Study:
- Explore reasons for diverse sex determination in reptiles.
- Investigate the prevalence and phylogenetic distribution of temperature-dependent sex determination (TSD).
- Propose a hypothesis for the evolution of TSD from genotypic sex determination (GSD) in reptiles.
Main Methods:
- Phylogenetic analysis of sex determination modes.
- Review of reptilian embryonic development and thermal environments.
- Theoretical modeling of evolutionary transitions between GSD and TSD.
Main Results:
- Reptiles are predisposed to evolving TSD from GSD.
- Variable thermal environments during critical embryonic periods favor TSD evolution.
- Mechanisms of sexual phenotype canalization influence TSD emergence.
Conclusions:
- Reptilian embryonic thermal lability provides raw material for TSD evolution.
- Natural selection can favor TSD when advantageous.
- Cryptic genetic variation released by developmental challenges may accelerate GSD-TSD transitions.
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