Meeting Abstract
Cichlid fishes of the East African rift lakes have produced the most remarkable adaptive radiations in vertebrate feeding morphology ever described. Intermediate in age between Lake Victoria and Tanganyika, Lake Malawi contains cichlid species with tremendously diverse head morphologies, but also the potential to hybridize and produce viable offspring. These conditions make Malawi cichlids ideal for the discovery of novel loci regulating vertebrate head morphology and their adaptive variants. While previous genetic studies of trophic divergence in Lake Malawi focused on the rock-dwelling mbunas, we selected two open-water dwelling cichlids – utaka, with distinct head shapes to produce a mapping cross. The sire represents Dimidiochromis compressiceps – a piscivorous species with a long and laterally compressed head, which feeds on smaller fish. The dam represents Copadichromis azureus – a planktivorous species with a shorter head more typical of utaka species. These species were selected for their extreme craniofacial morphological differences, which genetic basis is unknown. As an initial step in our quantitative trait locus mapping project, we will present a quantitative morphometric analysis of head elements of D. compressiceps, C azureus and their F1 progeny to determine which morphological traits most strongly differentiate these two species. Our preliminary observations indicate that greatest morphological differences are seen in the oral jaw skeleton and neurocranium, and that these differences have already appeared at larval stages.
