9623881 KOCHER The fauna of cichlid fish (Pisces: Cichlidae) in Lake Malawi (eastern Africa) represent a level of species diversity unparalleled in other vertebrate lineages. Lake Malawi contains an estimated 500 distinct species, most of which are found only in this lake. It is thought that this high level of biodiversity has been generated during the relatively short time that Lake Malawi has been in existence. Many researchers believe that the forces responsible for generating this species richness are still operating today. One model, the Dominey hypothesis, suggests that extreme philopatry (greatly reduced migration between populations) and the development of distinct mate recognition systems within each population, have resulted in the emergence and maintenance of the many Lake Malawi cichlid species. Until now, tests of this hypothesis have been difficult to design and implement. In this study, Jeffrey Markert, under the direction of Thomas Kocher, will use detailed field sampling techniques, laboratory mate-choice experiments, and molecular markers to evaluate the geographic and behavioral components of the Dominey hypothesis. DNA fingerprinting, combined with a fine scale survey of cichlid populations along the eastern shore of Lake MalawiOs Nankumba Peninsula, will assess the extent of philopatry in these populations; the prediction is that these fish hardly ever Oleave homeO. DNA fingerprinting will also be combined with laboratory experiments in which fish, raised in an enclosure that closely replicates natural conditions, are permitted to choose mates from multiple populations; the prediction is that the fish will prefer members of their own population. The results of this study will test the ability of the Dominey hypothesis to model species diversity in Lake Malawi cichlid fish. It will help assess whether the Dominey hypothesis applies only to species diversity in Lake Malawi cichlid fish or can be applied more generally.
