The impact of hybridization on the genome of megadiverse haplochromine cichlids (Cichlidae)
Final Report Abstract
Through hybridization a variety of new characters can arise, increasing variation and potentially contributing to the formation of new species. Little is, however, known about the genomic architecture of hybridization and hybrid speciation, mainly because of the lack of extensive genomic data. In the proposed project I was planning to study the genomic architectures of hybrid incompatibilities in cichlids based on experimentally generated early generation hybrids (F2 hybrids between several cichlid species) as well as in established hybrids. Due to several reasons the project could not be carried out as planned, and I shifted my focus towards (a) mate choice and segregation of coloration in second-generation (F2) hybrids and (b) generation of a first linkage map and mapping of male nuptial coloration in Lake Victoria cichlids. Mate choice experiments were conducted with F2 hybrids of a cross for which a study in 2014 showed, that female F1 hybrids preferred to mate with F1 hybrid males compared to parental species. Furthermore male nuptial coloration in the F1 hybrids covered a different coloration range than both parental species. The question was, whether female F2 hybrids of the same cross still prefer to mate with F2 hybrids, or if the reproductive barrier of the F1 breaks down in the F2 generation. Mate choice experiments were set up and female choice and male coloration were analyzed based on paternity tests and color characteristics collected based on individual spots on the males’ body. A clear preference of females for one parental species resembling the F2 males in coloration, but not for the F2 hybrids, could be shown, indicating the breakdown of reproductive barriers in the F2. In the second project a linkage map was generated corresponding with the expected number of chromosomes in the genus Pundamilia. We found one major QTL for sex, but yet no clear QTL for color traits. The project is still ongoing and we work on the optimization of the genomic analysis to minimize the impact of potential sequencing errors and on the scoring of color traits.
