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Evolution by fisherian sexual selection in diploids
Philip B Greenspoon1, Sarah P Otto
1University of British Columbia, Department of Zoology, Vancouver, British Columbia, Canada, V6T 1Z4. pbg@interchange.ubc.ca
Evolution; International Journal of Organic Evolution
|February 25, 2009
Summary
Diploid sexual selection models reveal that ploidy significantly impacts evolutionary dynamics, unlike haploid assumptions. Sexual and natural selection can drive populations away from equilibrium in diploids, especially with trait underdominance.
Area of Science:
- Evolutionary biology
- Population genetics
Background:
- Fisherian sexual selection models commonly assume haploid genetics.
- Ploidy is known to influence evolutionary dynamics, particularly near fixation boundaries.
Purpose of the Study:
- To model sexual selection in diploid organisms away from fixation boundaries.
- To characterize evolutionary dynamics under diploidy with viability and preference loci.
Main Methods:
- Developed a diploid model with two di-allelic loci: one for a male-limited trait under viability selection, and one for female mating preference.
- Employed a quasi-linkage equilibrium (QLE) approach to analyze the system.
Main Results:
- Derived a general equation for curves of quasi-neutral equilibria and their stability (attracting/repelling).
- Demonstrated that diploid systems can deviate from internal equilibrium curves, unlike haploid models.
- Identified that combined natural and sexual selection inducing underdominance at the trait locus causes this deviation.
Conclusions:
- Ploidy is a critical factor in Fisherian sexual selection dynamics.
- Diploid models reveal novel evolutionary pathways not predicted by haploid assumptions.
- Underdominance at the trait locus, driven by combined selection pressures, can destabilize equilibria in diploid populations.
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