Meeting Abstract

49.1  Monday, Jan. 5  Single origin of a lake-wide pigmentation locus in the rock-dwelling cichlids of Lake Malawi. ROBERTS, Reade B.*; KOCHER, Thomas D.; University of Maryland, College Park reade@umd.edu

The phenotypic diversity present in the cichlid fishes of Lake Malawi is amazingly rich given the relatively short history in which it has evolved. Perhaps the most varied set of phenotypes is found within pigmentation, with nuptial coloration at times defining, and possibly driving, species boundaries. Extremely similar pigmentation characters repeatedly appear across the Malawi cichlid flock, often in species separated by both geographic and phylogenetic distance. While such a pattern suggests repeated convergent evolution of pigmentation phenotypes, the same pattern could also arise as a result of the sorting of ancestral pigmentation genes, or the migration of pigmentation genes during rare interspecific hybridization events. Here we report the fine mapping of a genetic locus underlying the orange blotch pigmentation phenotype found in four distinct genera throughout Lake Malawi. Our results reveal a single haplotype, and thus a single origin, of the orange blotch locus, as well as some compelling candidates for the gene responsible for the phenotype. Additionally, the orange blotch locus accounts for a range of distinct blotched phenotypes. The single genetic origin of a phenotypic trait found throughout the lake has profound implications to understanding this particularly speciose vertebrate radiation, as well as to future utilization of the Lake Malawi cichlid flock as a model to understand gene function and the evolution of adaptive traits.