Genomics of hybridization, speciation and phenotypic evolution in Wheatears

Identifying the genomic regions underlying species and phenotypic diversification and the processes through which they evolve is a central goal of evolutionary biology. Hybridizing species offer unique opportunities in this context: First, phenotypes else locked up within parental species are recombined in hybrids. Second, genomic regions involved in species evolution can be identified as ones resisting genetic exchange between parental species, whereas an exchange of genetic variation can take place in the remainder of the genome. In my PhD project, I take advantage of pervasive hybridization between two color-polymorphic songbird species, Oenanthe melanoleuca and O. pleschanka. Based on haplotype-resolved whole-genome re-sequencing data from hybrid zones in W Kazakhstan, Iran, the Caucasus, and Romania/Bulgaria and throughout the ranges of these species, my work aims to map genomic regions underpinning plumage coloration and identify regions involved in reproductive isolation. We will back up the identification of these candidate regions with genomic data from a historical transect across the Iranian hybrid zone. To this end, I will first reconstruct the histories of colonization and hybridization based on the haplotype-resolved genomic data. Second, I will investigate the molecular basis of color phenotypes by identifying genomic regions with elevated differentiation between phenotypes and where individuals cluster by phenotype instead of species. Third, in a comparative population genomic approach, I will infer candidate genomic regions involved in speciation. The combination of a unique model system with these data promises novel insights into the origins and evolutionary history of adaptation and speciation. Thereby the project will shed light on the potential of hybridization as a fast track towards adaptation in the face of climate change.