Repeated Adaptive Introgression at a Gene under Multiallelic Balancing Selection

Sample size: 68 publication 10 minutes Evidence: high

Author Information

Author(s): Castric Vincent, Bechsgaard Jesper, Schierup Mikkel H., Vekemans Xavier

Primary Institution: Université des Sciences et Technologies de Lille 1

Hypothesis

Does negative, frequency-dependent selection on alleles at the multi-allelic gene controlling pistil self-incompatibility specificity in two closely related species cause introgression at this locus at a higher rate than the genomic background?

Conclusion

The study found that introgression of S-alleles between two closely related Arabidopsis species occurs at a higher rate than the genomic background, suggesting adaptive introgression facilitated by balancing selection.

Supporting Evidence

Introgression rates for S-alleles were found to be five times higher than the genomic background.
Polymorphism at the S-locus is largely shared between the two species.
The study provides the first documented example of adaptive introgression facilitated by balancing selection.

Takeaway

Plants can share genes with their relatives more easily than other parts of their DNA, which helps them adapt better to their environment.

Methodology

The study analyzed sequence diversity at the SRK gene in two species of Arabidopsis and compared levels of divergence at fourfold degenerate sites between trans-specifically shared S-alleles and the genomic background.