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Evolutionary stability inferred for a free ranging lizard with sex-reversal
Kristoffer H Wild1, John H Roe2, Lisa Schwanz3
1Centre for Conservation Ecology and Genomics, Institute for Applied Ecology, University of Canberra, Canberra, Australian Capital Territory, Australia.
Molecular Ecology
|February 18, 2022
Summary
High incubation temperatures can reverse sex in Central Bearded Dragons, but low population structure and modest sex-reversal rates suggest their sex determination system is currently evolutionary stable. Further shifts may occur with climate change.
Area of Science:
- Evolutionary biology
- Herpetology
- Genetics
Background:
- Vertebrate sex is typically genetic, but reptiles can exhibit temperature-dependent sex determination (TSD).
- In some species, temperature can override genetic sex, leading to sex reversal.
- The Central Bearded Dragon (Pogona vitticeps) has a ZZ/ZW system but can undergo temperature-induced sex reversal from ZZ males to ZZ females.
Purpose of the Study:
- To investigate the evolutionary stability of sex determination in Pogona vitticeps.
- To assess the impact of temperature-dependent sex reversal on population genetics and individual fitness.
- To evaluate the potential for future transitions in sex determination mechanisms.
Main Methods:
- Genotype-by-sequencing (GBS) for genetic structure analysis.
- Phenotypic and chromosomal sex identification.
- Extensive field surveys and radio telemetry for movement, space use, and survival.
- Assessment of sex-reversal rates in a known hot spot.
Main Results:
- Low population genetic structure (FST ~0.001) was observed.
- A modest rate of sex-reversal (~17%) was recorded.
- Sex-reversed and non-sex-reversed females exhibited similar survival and behavioral traits.
Conclusions:
- The current sex determination system in Pogona vitticeps appears evolutionarily stable.
- While a gradual transition is possible with increased landscape fragmentation and rising global temperatures, rapid shifts are unlikely under current conditions.
- The fitness of sex-reversed individuals does not currently drive rapid transitions.
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