Understanding the role of Pleistocene climatic oscillations for evolution. A palaeogenomic case study of the European crow hybrid zone

• Applicant: Professor Dr. Jochen B. W. Wolf
• Subject Area: Evolution, Anthropology ; Ecology and Biodiversity of Animals and Ecosystems, Organismic Interactions
• Term: since 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 510399081

Speciation unfolds in space and time. Reproductive isolation between diverging populations most easily evolves during periods of geographic isolation and is put to the test upon secondary contact. Under the influence of ensuing gene exchange, the accumulated genome-wide divergence is expected to erode except around mutations experiencing divergent selection. Climatic oscillations during the Quaternary have presumably fueled such spatio-temporal population dynamics: during unfavorable environmental conditions populations contracted into disparate refugia, expanding their range as soon as conditions improved. This popular biogeographic model has gained support by population reconstruction based on genetic signatures of remnant population samples. It has rarely been tested using direct genetic evidence. Ancient genetic material can fill this gap as it allows observation of population dynamics through space and time. As a model, we here use the well-studied contact zone between grey-coated hooded and all-black carrion crows in Europe, hypothesized to be shaped by repeated events of isolation and recolonization during glacial-interglacial cycles. Combining genome-wide information from ~50 ancient samples (70,000 - 500 BP) with previously sequenced genomes from 118 extant individuals will allow (1) reconstructing the demographic history of European crows in space and time and (2) track the allelic dynamics of genes subject to sexual selection with known effects on prezygotic isolation. This research program allows direct scrutiny of the prevailing biogeographic model of biodiversity and provides fundamental insight to the dynamics of speciation.

• DFG Programme: Research Grants