The historical biogeography of the freshwater fish fauna of rivers in Zambia have been studied using serranochromine cichlids as an example.
The study by Cyprian Katongo, Stephan Koblmller, Nina Duftner, Luke Mumba and Christian Sturmbauer, is published in the most recent issue of the journal Molecular Phylogenetics and Evolution.
The authors used both a representative taxonomic sampling of three genera (Pharyngochromis, Sargochromis and Serranochromis) and nine species and a biogeographic sample of nine sampling localities in two major and four minor watersheds to investigate the pathways and timing of the evolution of serranochromine cichlids in Zambian rivers based on sequence data from two mitochondrial gene segments.
Analyzing a 1047 base-pair sequence of the ND2 gene and a 358 base-pair sequence of the D-loop gene, the authors found that the Zambian serranochromine cichlids were grouped into 5 ancient clades whose common ancestor most likely invaded from the lower Congo River.
According to the authors: The five clades originating in the Congo River drainage diversified further; one stayed in the Congo drainage, one diversified in the Zambezi system only, while the three clades of mixed distribution underwent diversification in the Zambezi system, to re-enter the Congo drainage very recently... Our hypothesis is consistent with the suggested radiation in the extinct Lake palaeo-Makgadikgadi, so that we propose that the Zambian serranochromine fauna in part represents survivors of the extinct lacustrine flock plus several novel species that originated in situ.
For more information, see the paper: Katongo, C, S Koblmller, N Duftner, L Mumba and C Strumbauer (2007) Evolutionary history and biogeographic affinities of the serranochromine cichlids in Zambian rivers. Molecular Phylogenetics and Evolution 45, pp. 326"338.