Evolution in ancient lakes: radiation of Tanganyikan atyid prawns and speciation of pelagic cichlid fishes in Lake Malawi

Atyid prawns from Lake Tanganyika are still poorly understood. There are at least 11 species sharing an exceptionally small size and a reduction in the number of branchiae. The majority are benthic although some are pelagic. This is reflected in different morphologies of the body and walking legs. Morphological adaptions of the denticles on the chelipeds are adaptive as they relate to different ways of feeding. Pelagic fish from Lake Malawi do not represent an example of sympatric speciation as suggested by Shaw et al. (2000). It is more likely that several, independent radiations started from inshore generalists, which gradually adapted to the openwater.