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Evolution of sexual asymmetry
Tamás L Czárán1, Rolf F Hoekstra
1Theoretical Biology and Ecology Research Group of the Hungarian Academy of Sciences and Eötvös University, H-1117 Budapest, Pázmány Péter sétány 1/c, Hungary. czaran@ludens.elte.hu
BMC Evolutionary Biology
|September 24, 2004
Summary
The evolution of two mating types, or sexual dimorphism, is explained by spatial population structure. This structure, particularly in aquatic environments, facilitates the development of binary mating systems over self-mating types.
Area of Science:
- Evolutionary Biology
- Theoretical Biology
- Population Genetics
Background:
- The prevalence of two-gender sexual reproduction is a long-standing puzzle in evolutionary theory.
- The question of why sexual organisms predominantly utilize a binary mating system remains less explored than the existence of sex itself.
Purpose of the Study:
- To investigate the evolutionary origins of binary mating systems (sexual dimorphism).
- To provide a feasible solution to the evolution of dimorphic sexual asymmetry using theoretical models.
Main Methods:
- Utilized a spatial model (cellular automaton) and its non-spatial approximation (mean-field).
- Compared the outcomes of spatial and non-spatial models to understand the role of population structure.
- Assumed an inherent fitness advantage for sexual reproduction over clonal multiplication.
Main Results:
- Spatial population structure, characterized by largely clonal self-aggregated gamete types, significantly facilitates the evolution of a binary mating system.
- The spatial model predicts the selective removal of self-mating gamete types.
- The non-spatial model, however, allows for the coexistence of self-mating and distinct mating types.
Conclusions:
- Spatial structure, especially in aquatic habitats, offers an ecological explanation for the evolution of mating types.
- The study resolves a theoretical problem that previous models based on random encounters could not address.
- The findings suggest that ecological factors, specifically spatial distribution, are crucial for understanding the prevalence of binary mating systems.