The role of the Yala swamp lakes in conservation of Lake Victoria region haplochromine cichlids: evidence from molecular genetic and trophic ecology studies

Lake Kanyaboli (Kenya), a satellite lake of Lake Victoria, has been suggested as a potential refugium for haplochromine cichlids that have gone extinct in Lake Victoria. We employed mitochondrial DNA and microsatellite DNA molecular markers as well as feeding ecology studies to re- evaluate the evolutionary and ecological significance of Lake Kanyaboli haplochromines. The mitochondrial DNA and microsatellite markers revealed high genetic diversity in the endangered Xystichromis phytophagus and also the presence of mtDNA haplotypes that may have either gone extinct in Lake Victoria or have arisen in situ. Lake Kanyaboli thus acts as a ‘genetic reservoir’ for the Lake Victoria species flock. Gut content analysis revealed six trophic groups among the six haplochromine species. The haplochromine community in Lake Kanyaboli therefore exhibits trophic specializations. The relatively high trophic diversity in this cichlid community contrasts with the currently simplified trophic relationships of Lake Victoria. This high trophic diversity contributes to high energy flow and overall ecological efficiency of the lake. Lake Kanyaboli and similar satellite lakes therefore provide an opportunity for conservation of both genetic and trophic diversity threatened by introduction of exotics in the Lake Victoria basin. Lake Kanyaboli should thus be recognized as an important Evolutionary Signficant Unit (ESU) for Lake Victoria region haplochromine species. Basin wide molecular genetic characterization of the other tilapiine cichlid species as a basis of identifying genetically robust stocks that can be used in aquaculture or to restock Lake Victoria should be undertaken.