Shared Selection and Genetic Architecture Drive Strikingly Repeatable Evolution in Long-Term Experimental Hybrid...

Area of Science:

• Evolutionary Biology
• Genetics
• Ecology

Background:

• Understanding evolutionary repeatability is key to predicting evolutionary trajectories.
• Hybridization is a significant source of genetic variation and evolutionary innovation.
• Genomic architecture and recombination rates can influence selection pressures.

Purpose of the Study:

• To investigate the factors controlling evolutionary repeatability in hybrid populations.
• To determine the extent of parallel evolution in experimentally evolved sunflowers.
• To assess the roles of natural selection, genomic architecture, and recombination in shaping evolutionary outcomes.

Main Methods:

• Experimentally evolved four replicate hybrid sunflower populations at natural sites for up to 14 years.
• Tracked introgressed ancestry across the genome to identify regions under selection.
• Analyzed the influence of recombination rate on selection against introgressed ancestry.

Main Results:

• Observed strong negative selection against introgressed ancestry on most chromosomes, with positive selection on one.
• Found that high recombination rates reduced selection against introgressed ancestry.
• Demonstrated highly parallel evolution across replicates, with shared selection driving 88% of introgressed allele frequency changes.

Conclusions:

• Evolutionary processes, particularly through hybridization, can be highly repeatable.
• Natural selection, genomic architecture, and recombination are central to evolutionary repeatability.
• This study confirms the predictive potential of evolutionary biology.