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Selection for pollen competitive ability in mixed-mating systems
Madeline A E Peters1, Arthur E Weis1,2
1Department of Ecology and Evolutionary Biology, University of Toronto, 25 Willcocks Street, Toronto, ON M5S 3B2, Canada.
Evolution; International Journal of Organic Evolution
|September 9, 2018
Summary
Selfing significantly impacts the evolution of plant genes controlling pollen competitiveness and diploid fitness. High selfing rates can prevent the spread of beneficial pollen traits, even with weak opposing selection.
Area of Science:
- Plant evolutionary genetics
- Population genetics
- Molecular evolution
Background:
- Gene coexpression in sporophytes and gametophytes allows for correlated selection.
- Pollen competitiveness alleles typically fix under outcrossing unless antagonistic pleiotropy is strong.
- Selfing alters competition dynamics, making individual pollen competitiveness less relevant.
Purpose of the Study:
- To model the evolution of a gene locus with pleiotropic effects on pollen competitiveness and diploid fitness.
- To investigate the role of selfing rates in the maintenance and spread of pollen competitiveness genes.
- To determine conditions for the maintenance of genetic polymorphism under mixed mating systems.
Main Methods:
- Development of two one-locus, two-allele population genetic models.
- Analytical solutions to determine invasion conditions for beneficial alleles.
- Analysis of polymorphism maintenance based on selfing rates and selection coefficients.
Main Results:
- Minimum and maximum selfing rates were derived for the invasion of alleles with superior diploid and haploid fitness.
- Genetic polymorphism is maintained only when diploid selection is recessive.
- High selfing rates can prevent the fixation of advantageous pollen competitiveness alleles, even with weak sporophytic counterselection.
Conclusions:
- Selfing plays a critical role in the evolution of genes affecting pollen competitiveness in plants with mixed-mating systems.
- The rate of selfing critically influences the spread and maintenance of alleles conferring enhanced pollen competitiveness.
- Selfing can expand or limit the range of selection coefficients that permit genetic polymorphism, depending on dominance and selfing mode.
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