Lake Victoria flameback (Pundamilia nyererei) in my aquarium

My interest in cichlids was originally triggered by Tijs Goldschmidt’s book Darwin’s Dreampond: Drama in Lake Victoria. In his book, Goldschmidt discussed the evolution of the Lake Victoria cichlid flock in light of the relatively recent origin of the Lake (approximately 14,000 years). Work continues on identifying the evolutionary history of the Lake Victoria cichlids – are they all descended from one species when the Lake formed, or was there a number of species which evolved in smaller lakes that subsequently merged?

Goldschmidt also discussed what has happened to the Lake’s cichlids since the introduction of the Nile perch, a large piscivorous fish. Cichlid numbers have plummeted, almost half the species have become extinct and many more are severely threatened. Lake Victoria held great potential both as a source for aquarium fish and for research into the mechanisms of evolution. The sociological impact of the introduction was covered in the rather disturbing but highly recommended movie Darwin’s Nightmare, by Hubert Sauper.

Cichlids are in the news at the moment due to a couple of studies. One discusses the role of colour vision in sympatric speciation (when species diverge without geographic isolation), focussing on Pundamilia nyererei and Pundamilia pundamilia. Mate selection in these species is based on visual cues, particularly in the red wavelengths for P. nyererei and in the blue wavelengths for P. pundamilia. Varying light conditions due to depth of habitat has driven the evolution of these two species from an intermediate.  Unfortunately, pollution in Lake Victoria is now starting to interfere with this mate recognition, with the possibility of the two species merging back into one. This research is detailed in the current issue of Nature (pay access only), but news reports can be found at Discover’s, Science Daily,  and the New York Times.

The other research is described at Practical Fishkeeping, and concerns analysis of mitochondrial DNA in Lake Tanganyikan cichlids which has revealed that the evolution of new species in the Lake has proceeded at a far slower rate than in Lake Malawi or Lake Victoria. The above mentioned finding about water clarity possibly merging species and hence being a barrier to the formation of a species flock is cited as one explanation, another is the presence of a lamprologine cichlid population in the Lake retarding the evolution of a later arrival of haplochromine cichlids, which are responsible for the rapid speciation in the other lakes.