The Cichlid Fishes of Lake Malawi, Africa

Abstract of Publication

Van Staaden, M.J., R. Huber, L.S. Kaufman, and K.F. Liem. 1994. Brain evolution in cichlids of the African Great Lakes: Brain and body size, general patterns, and evolutionary trends. Zoology 98 (1994/95): 165-178.  

The cichlid fish communities of the East African Great Lakes are amongst the richest concentrations of vertebrate species on earth. These "explosive" radiations represent an unequaled system to address central questions in evolutionary biology, and have therefore figured prominently in studies of speciation, ecological plasticity, and molecular evolution. Cichlid radiations in the three major lakes (Victoria, Tanganyika, and Malawi) are generally similar in terms of trophic diversity, species richness, and rates of endemism. However, being largely independent of each other, they offer a true evolutionary experiment with treatment groups and replicates. Using computer-based morphometric methods, we compared brain morphology among 189 cichlid species from the East African Lakes and Madagascar. The Madagascan taxa were included as phylogenetically primitive representatives of the family Cichlidae. In this first paper we report data on the relationship between brain and body size, and address patterns of brain form variation among individuals, lakes, and sexes. Cichlid faunas of the three lakes, encompassing three putative subfamilies, exhibit surprisingly similar variation in the form of brain structures concerned with vision, olfaction, and the lateral line. However, across the African lakes, the greatest variation was observed in the development of association centres, in particular of the telencephalon. The lack of negative associations among brain regions across lakes indicated that enhanced development of one brain structure for a particular function is not compensated for by reduction of other modalities.




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