Genomics of hybridization, speciation, and phenotypic evolution in wheatears

• Applicant: Dr. Reto Burri
• Subject Area: Evolution, Anthropology
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 413417083

Nature is home to a splendid diversity in form and coloration, yet we only begin to unravel the complex molecular and evolutionary mechanisms underpinning the many ways in which species and individuals differ among each other. Owing to recent technological revolutions, we now have unprecedented access to genome-wide molecular diversity and, consequently, can start tackling some of the most pertinent questions regarding the evolution of this biodiversity:• What is the genetic architecture of species‘ boundaries and phenotypic adaptation?• What are the roles of ancestral vs new genetic variants, and of introgression upon hybridization in the evolution of phenotypes and adaptation, and how are the latter maintained?• In particular, what are the origins of genetic variation underlying convergent phenotypes?My research proposed here is designed to provide insights into these questions in a unique, yet genetically largely unstudied system of colour-polymorphic songbirds – black-eared and pied wheatears (Oenanthe hispanica and O. pleschanka). Making use of the natural laboratory provided by pervasive hybridization between these species repeated in three geographic regions, I aim to:• Identify candidate genomic regions involved in the evolution of species and colour phenotypes using a novel comparative population genomic framework and admixture mapping.• Determine genomic regions resisting gene flow in all hybrid zones that are likely involved in reproductive isolation.• Infer whether the outcome of hybridization varies among hybrid zones (sensu Gompert et al. 2016).• Infer the roles of gene flow and selection in the evolution of phenotypic hybrid zone structure.Conspicuous colour phenotypes are replicated across the entire genus Oenanthe, mirroring the polymorphism found in the two main study species. This pattern suggestive of convergent evolution, and the tracing of candidate regions across the genus empowers analyses to:• Infer whether genetic variants identified to be involved in species or phenotype evolution represent ancestral, introgressed, or novel variation.• Infer whether the same genomic regions are reused for the evolution of convergent phenotypes.Finally, the availability of a historical sample provides insights into the temporal dynamics of the phenotypic and genomic composition in one of the hybrid zones. Temporal analyses may provide evidence to corroborate particular genomic regions‘ involvement in species evolution and provide insights into the system‘s evolution towards or away from the completion of species barriers.The proposed research sets itself apart from similar studies by unique opportunities offered by the novel study system, and an integrative approach complementing a comparative population genomic framework (Burri 2017a) and admixture mapping with comparative and temporal perspectives.

• DFG Programme: Research Grants
• International Connection: Switzerland