Polygenic selection to a changing optimum under self-fertilisation.

Area of Science:

• Evolutionary biology
• Population genetics

Background:

• Polygenic traits are influenced by multiple genes across the genome.
• Previous studies on polygenic selection primarily focused on random-mating populations.
• Self-fertilization significantly alters genetic diversity, recombination, and genome segregation, impacting selection.

Purpose of the Study:

• To investigate the effects of self-fertilization on polygenic adaptation to new environments.
• To analyze how mating systems influence the realization of polygenic selection.
• To understand the genetic consequences of selfing during adaptation.

Main Methods:

• Analytical modeling to derive theoretical solutions for polygenic adaptation under selfing.
• Stochastic simulations to observe adaptation dynamics in populations with varying selfing rates.
• Examination of allele-frequency changes and linkage disequilibrium.

Main Results:

• Self-fertilization can increase adaptation to an environmental optimum.
• Linkage disequilibrium under selfing can initially slow favored mutation spread due to selection interference.
• High selfing rates (≥90%) promote higher long-term fitness and aid adaptation, especially with pleiotropic mutations.
• Selfing favors fixation of alleles with opposing trait effects and can lead to fixation of major variants with neutral hitchhikers.

Conclusions:

• Self-fertilization presents potential advantages for adapting to new environments.
• The mating system critically shapes the genetic architecture of polygenic adaptation.
• Understanding selfing's impact is crucial for predicting evolutionary trajectories in diverse species.