Genetic differences among the species of genus Aulonocara and related genera of Malawian cichlids

Abstract

In this study, our aim was to understand the genetic relationships between wild or bred individuals of a large fish group from Lake Malawi, genus Aulonocara, and related genera. The mtDNA control region was sequenced in 35 individuals representing 16 species from the genera Aulonocara and Sciaenochromis , and 15 species from the other 12 genera, including mbuna and non-mbuna. In a genetic tree, constructed with the Kimura-2 parameter as a distance, using the neighbor-joining method, many species of the genus Aulonocara formed a clade with mbuna, while only two species formed another clade with non-mbuna species. Similarly, Sciaenochromis fryeri was a member of a clade by mbuna, while S . sp. nyassae was a member of a clade formed by non-mbuna. Among the Aulonocara species, A. steveni and A . sp. ‘Lwanda’ were estimated to be relatively close to their ancestors using network analysis. Some individuals of A. hansbaenschi and S. fryeri bred in Asia were found to be far from purely bred ones. These results suggest the possibility of generating the genera Aulonocara and Sciaenochromis by hybridization between mbuna and non-mbuna, and indicate that there are some genetic disturbances within the species of these genera caused by human activities.