The Cichlid Fishes of Lake Malawi, Africa

Summary of Publication

Turner, G.F. 2000. The nature of species in ancient lakes: Perspectives from the fishes of Lake Malawi. Pp. 39-60 in Rossiter, A., and H. Kawanabe, eds. Ancient lakes: Biodiversity, ecology and evolution. Advances in Ecological Research, volume 31. Academic Press, London.  

In this review, the development of species concepts is discussed, both in practice and in principle, applied to the cichlid fishes of Lake Malawi. From 1864 to 1935, museum-based taxonomists with no information on the natural biology of the fishes had no alternative but to apply morphological species definitions. Since then, most descriptions have been carried out by field workers, generally employed on applied fisheries projects, again mostly using morphological criteria. The work of Fryer exemplifies the uncertainty over species concepts during this period, simultaneously demonstrating a profound knowledge of evolutionary theory and biological species concepts, and the difficulties of applying them in practice.

Following the pioneering SCUBA-assisted study of Holzberg in 1978, Ribbink and his co-workers developed a practical species definition for the rocky shore mbuna, based on male breeding colours in addition to behavioural, ecological and morphological features. Such practical species definitions are now used by almost all Malawi cichlid researchers, as well as those working on Lakes Victoria and Tanganyika. Many current workers, including the present author, believe that the most appropriate theoretical basis for this practice lies in the proposition that reproductive isolation between species is often the result of sexual selection by female choice. Rather surprisingly, one implication of this view is that appropriately designed laboratory studies can be used to test the specific status of allopatric populations. In a highly speculative discussion, it is suggested here that speciation mechanisms and species concepts appropriate for African lake cichlids probably have little relevance for other lacustrine endemic taxa.




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