Quantifying the Genetic Basis of Yellow Pigmentation in Lake Malawi Cichlids

Abstract

As a likely target of sexual selection via female mate choice, male nuptial patterns are thought to have played a role in the extraordinary diversification of Lake Malawi’s rock-dwelling (mbuna) cichlids. The extent to which male coloration can explain the rapid evolution of the mbuna clade, however, is dependent on its underlying genetic architecture. If male nuptial coloration is found to be mediated by few genes of large effect, then this genetic architecture could support rapid phenotypic evolution and offers a potential mechanism explaining the extraordinary diversity of Lake Malawi cichlids. To this end, this study aims to quantify the number of genetic factors and the mode of gene action influencing male xanthophores pigmentation in two closely related sympatric mbuna species of Lake Malawi. I estimate that xanthophore pigmentation in both scales and pelvic fins is regulated by few genes of large effect that exhibit epistatic effects. These results provide insight into the genetics of male coloration and add to a body of literature supporting pigmentation patterns’ roles in cichlid diversification.