Genetic architecture and selective sweeps after polygenic adaptation to distant trait optima

Area of Science:

• Population and quantitative genetics
• Evolutionary biology
• Genomics

Background:

• Understanding genetic basis of adaptation is key.
• Genome-wide data is available, but polygenic adaptation understanding is limited.

Purpose of the Study:

• Explore impacts of demography, trait genetics, and selection on adaptation rate, mode, and genetic architecture.
• Use forward-time simulation to model polygenic adaptation to an optimum shift.

Main Methods:

• Simulated sequence variation for 20 QTL across 12 demographies and 100 traits.
• Varied mutation effect size, selection strength, and genomic background.
• Used random forest regression to assess parameter importance.

Main Results:

• Selective sweeps occur even under weak selection and significant genetic background influence.
• Most sweeps originate from standing variation, but new mutations are crucial for strong selection/large optimum shifts.
• Population bottlenecks and expansions affect genetic variation, sweep dynamics, and adaptation speed.

Conclusions:

• Simulation models qualitatively recapitulate maize domestication traits.
• Results highlight complex population genetics of loci in quantitative trait models.
• Identified key factors driving complexity in polygenic adaptation.