Recent natural selection causes adaptive evolution of an avian polygenic trait.

Abstract

We used extensive data from a long-term study of great tits (<i>Parus major</i>) in the United Kingdom and Netherlands to better understand how genetic signatures of selection translate into variation in fitness and phenotypes. We found that genomic regions under differential selection contained candidate genes for bill morphology and used genetic architecture analyses to confirm that these genes, especially the collagen gene <i>COL4A5</i>, explained variation in bill length. <i>COL4A5</i> variation was associated with reproductive success, which, combined with spatiotemporal patterns of bill length, suggested ongoing selection for longer bills in the United Kingdom. Last, bill length and <i>COL4A5</i> variation were associated with usage of feeders, suggesting that longer bills may have evolved in the United Kingdom as a response to supplementary feeding.