Reproductive isolation among closely related Lake Malawi cichlids: can males recognize conspecific females by visual cues?

Little is known about mate recognition systems among the species-rich cichlid flocks of the African Great Lakes. Such knowledge is critical to our understanding of how evolutionary processes have brought about the current diversity. In the present study we focused on three anatomically similar species of rocky shore cichlid fish Pseudotropheus (Maylandia) spp. from Lake Malawi. We scored male responses to heterospecific and conspecific females which were enclosed in separate watertight transparent chambers. Any male behaviour we observed was therefore due to visual cues alone. Although males of some species could clearly identify conspecific females on visual cues alone, others could not. In cases where conspecific and heterospecific females were phenotypically similar, males could not consistently distinguish between them. Further experiments are required, however, to see whether males can recognize these females using alternative means, such as olfactory cues. Copyright 1999 The Association for the Study of Animal Behaviour.