Mate choice driven by genome in an allopolyploid fish complex

Nonsexual complexes which lack typical reproductive isolation and show multiple conspecific and heterospecific mating options among hybrids and parental species are excellent models to study mate choice based on genetics. The allopolyploid fish complex Squalius alburnoides includes multiple fertile male and female genomotypes reproducing among each other and with the sympatric species of the Squalius genus. We used this hybridogenetic complex to study the relationship between mate preference and mates’ genetic background, focusing on a population whose mating options include two Squalius species. The preference of S. alburnoides hybrid females towards multiple male genomotypes was assessed in affiliation trials, and the levels of admixture between the genomes of the two Squalius species were measured using next-generation genotyping. The genome of the most recent Squalius species in the drainage was admixed with variable genetic portions typically allocated to the other species, but not...