Allochronic diversification? Local seasonality as a driving factor for genetic and vocal divergence in an Afrotropical songbird

• Applicant: Dr. Barbara Helm
• Subject Area: Evolution, Anthropology
• Term: from 2011 to 2016
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 206116427

Speciation involves reproductive isolation between diverging populations. Determining initial reproductive barriers and the ecological forces that shape them is thus crucial for understanding evolution. This study examines the role of seasonal timing for local adaptation, progressive isolation and possibly speciation in a songbird, the African stonechat Saxicola torquata axillaris. Stonechats have robust circannual programs and breed annually under favourable seasonal conditions. Seasonality in East Africa varies over short distance, and could thereby impose barriers. Based on earlier indication of local divergence, the present study tests allochronic isolation in the field. Specifically, it uses the role of song in mate choice and local diversification to study behavioural isolation and relates it to genetic divergence. In principle, genes and vocalizations should both diverge with increasing distance. However, if timing promotes isolation and is communicated by song, local seasonality should have greater impact on differences in genes and song than expected from spatial distance. Furthermore, differences in genes and song could arise at different evolutionary rates. Allochronic isolation and geographically distinct song in Stonechats may play an essential role in genetic structuring and are likely to have important implications for the evolutionary dynamics, ecological flexibility, and adaptive ability of birds.

• DFG Programme: Research Grants