German scientists have studied the molecular phylogeny of the tilapiine cichlids and identified both the root of the East African (Rift Lake) cichlid radiation, as well as its time of origin.
Julia Schwarzer and coauthors used five nuclear and four mitochondrial genes to study the molecular phylogeny of the haplotilapiine cichlids, one of five major sublineages of cichlid fishes.
The haplotilapiines include the tilapiines, a large subgroup known to be paraphyletic (evolved from several ancestors).
The authors analyzed 5782 base pairs for 56 species and in the resulting phylogeny, recognized several new monophyletic subgroups of cichlids: (1) the Oreochromini, consisting of the mouthbrooding genera Oreochromis, Sarotherodon, Iranocichla and Tristramella; (2) the Boreotilapiini, consisting of species of Tilapia from western and central Africa, Gobiocichla wonderi and Steatocranus irvinei; and (3) the Austrotilapiini, consisting of southern African species of Tilapia and the East African cichlids.
Etia nguti was found to be the sister group of all other haplotilapiines. The East African cichlids were found to be the sister group of a group of southern African substrate-brooding tilapiine cichlids, with the authors calculating this divergence to have occurred 14"26 million years ago.
For more information, see the paper: Schwarzer, J, B Misof, D Tautz and UK Schliewen (2009) The root of the East African cichlid radiations. BMC Evolutionary Biology 9, 186 doi:10.1186/1471-2148-9-186.