The Study of Gene Exchange During Recent Speciation Events among Cichlids of Lake Malawi

Rutgers University New Brunswick, New Brunswick NJ

Investigators

Abstract

There are over one thousand species of fish in the family Cichlidae (Cichlids) throughout the world, but surprisingly most of this diversity occurs in the great African lakes, Malawi (Nyasa), Tanganyika, and Victoria. These lakes are not of great age, in evolutionary terms, and biologists are puzzled over how the hundreds of unique Cichlid species, that exist in each of these lakes, could have arisen quickly. The traditional model of species formation assumes that separate species first begin as isolated populations that do not exchange genes. However, an important alternative model that could apply where there are not sharp barriers to migration, is that species arise without population separation. This model includes gene exchange between newly forming species, as well as natural selection acting to cause divergence. It is an interesting model, but difficult to test. In this project, researchers will test the model by applying a newly developed genetic procedure for detecting recent gene exchange between several Cichlid species from Lake Malawi. The Cichlids of Lake Malawi have become a model system for many researchers studying speciation. Yet the critical question here, as in other cases of recently formed species, is whether natural selection has caused the divergence directly, or whether species arise as completely separate populations that diverge separately. This question is fundamental to the understanding of how biological diversity arises.