In the lakes of East Africa, fishes of the family Cichlidae have undergone an extraordinarily rapid and extensive radiation. At least 1500 species of cichlid ('sick-lid') fish have evolved from a common ancestor in the last 10 million years. Within Lake Malawi over 700 species have arisen within just the last 2 MY.

We want to know how new species evolve. What evolutionary forces contribute to speciation? What is the genetic basis of phenotypic differences among closely related species?

A number of factors are at work, including trophic specialization and sexual selection. We suspect that rapid evolution of male traits and female preferences contributes to pre-mating isolating mechanisms among local populations, facilitating speciation over small spatial scales.

Our approach is to map and identify genes responsible for the phenotypic differences among species. We have performed QTL studies of jaw and tooth morphology to understand the genetic basis of trophic specialization. Our current work is focused on the genetic basis of pigmentation and sex determination in Lake Malawi cichlids. We are also interested in the genetic basis of olfactory communication.

Our ultimate goal is to identify the genes responsible for speciation of these fishes, and to study the geographic distribution of allelic variants among populations and species in the wild.



Labeotropheus trewavasae


Pseudotropheus tropheopsTropheops.jpg

Melanochromis auratusMelanochromis.jpg
Images by Justin Marshall