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Temperature-dependent turnovers in sex-determination mechanisms: a quantitative model
Christine Grossen1, Samuel Neuenschwander, Nicolas Perrin
1Department of Ecology and Evolution, University of Lausanne, CH-1015 Lausanne, Switzerland. christine.grossen@unil.ch
Evolution; International Journal of Organic Evolution
|August 21, 2010
Summary
Sex determination is a continuum, not a dichotomy. Temperature and genetic factors interact, influencing sex determination mechanisms and potentially driving evolutionary turnovers in sex-determining genes.
Area of Science:
- Evolutionary biology
- Genetics
- Environmental science
Background:
- Sex determination is typically viewed as dichotomous: genetic (GSD) or environmental (ESD), often temperature-dependent (TSD).
- Existing models often treat GSD and TSD as separate, mutually exclusive systems.
Purpose of the Study:
- To propose a unified view of sex determination as a continuum where genetic and environmental factors interact.
- To formalize a quantitative-genetics framework for defining sex determination systems at the population level.
Main Methods:
- Developed a quantitative-genetics model treating sex as a threshold trait.
- Incorporated reaction norms to model interactions between genotypic and temperature effects.
- Defined sex determination systems by the proportion of variance in phenotypic sex attributed to genetic vs. environmental factors.
Main Results:
- Demonstrated that temperature changes can induce shifts in sex determination mechanisms, leading to large-scale sex reversal.
- Predicted that environmental changes will drive selection for alternative sex-determining genes.
- Linked the frequency of sex determination system turnovers and homomorphic sex chromosomes to temperature dependence.
Conclusions:
- Sex determination systems exist on a continuum influenced by both genetic and environmental factors.
- Climate change and other environmental shifts are expected to alter sex determination mechanisms and sex ratios.
- Understanding this continuum is crucial for predicting evolutionary responses in species with temperature-dependent sex determination.
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