Examination of geographic variation in male melanistic color pattern in the Lake Malawi Maylandia zebra cichlid species

The purpose of this thesis project is to examine geographic variation in male melanistic color pattern in the Lake Malawi cichlid Maylandia zebra. Maylandia zebra, like other members of Lake Malawi’s rock-dwelling cichlid clade, are highly philopatric, meaning very few individuals migrate into or out of geographically isolated populations. The genetic isolation of these populations may facilitate their phenotypic differentiation and contribute to the extraordinary rate of speciation observed in this system. I will test the hypothesis that populations of M. zebra are phenotypically isolated by examining the within and between population variation in male melanistic pigmentation. Specifically I will quantify bar density and pigment intensity from photos of M. zebra from differing locations in order to quantify phenotypic variation. Next, I will test the hypothesis that geographic variation in pigmentation pattern is correlated with environmental conditions at each site. To do this, I will quantify the number of rocks for the location of each population. I predict that populations with larger than average melanistic patterning will live in habitats with many smaller rocks. This analysis will provide insight into the ecological forces influencing population differentiation of Lake Malawi cichlids and may inform on the speciation process in this system.