Author marked in boldface is EvolEcol member.
Wilkins M.R., Scordato E.S.C., Semenov G.A., Karaardıç H., Shizuka D., Rubtsov A., Pap P.L., Shen S-F., Rebecca J. (2018). Global song divergence in barn swallows (Hirundo rustica): exploring the roles of genetic, geographic, and climatic distance in sympatry and allopatry. Biological Journal of the Linnean Society in press.
Divergence in acoustic signals plays an important role in the production and maintenance of biodiversity in numerous taxa. In this study, we assess patterns of acoustic divergence in geographically isolated and sympatric subspecies of barn swallows (Hirundo rustica), including analyses of whether song differentiation varies with geographic isolation, genetic distance, and climatic distance. We provide the first description of geographic variation in
song among five of six currently recognized barn swallow subspecies. Temporal traits
describing terminal trills were the most distinct song traits among subspecies, adding to
growing evidence that trills are important in speciation among many birds, insects, and fish. Across a ~6,000 km transect of Russia, acoustic distance was predicted by genetic and geographic distance, but not climatic distance. We also found no reproductive character displacement of song traits in a contact zone between H. r. rustica and H. r. tytleri. Based on patterns discovered in this study, we infer an important role of genetic drift and sexual selection in the gradual buildup of acoustic divergence, which is accelerated in small populations.
Keywords: acoustic adaptation – acoustic divergence – barn swallow – birdsong – ecological selection – Hirundo rustica – neutral drift – reproductive character displacement – sexual selection – speciation