download my PhD thesis here

Research

Poison or Passion: warning and attraction in a colour polymorphic frog

The poison frog Oophaga pumilio is a small Dendrobatid frog (~2 cm), coloured bright red and blue throughout most of its range from Nicaragua to Panama. But in the Bocas del Toro Archipelago in western Panama, the species shows extreme colour variation among populations, ranging from orange to yellow to blue, sometimes with black spots or stripes. During my postdoc at UT Austin, I investigated the roles of natural and sexual selection in explaining this colour diversity.

Sexual selection and speciation in Lake Victoria cichlid fish

(PhD project at the University of Leiden)

The haplochromine cichlids of Lake Malawi and Lake Victoria are classic examples of explosive speciation: hundreds of species have evolved very rapidly in both lakes. The widespread occurrence of intra- and interspecific variation in male nuptial coloration and corresponding female mating preferences has inspired the hypothesis that sexual selection has played a major role in the origin of these species flocks. In my PhD project, I used two model systems to test some of the predictions that follow from this hypothesis, and I studied the evolutionary mechanisms that underlie mate choice for colour patterns.

The colours of speciation: can visual adaptation and sexual selection drive species divergence in cichlid fish?

Environmental heterogeneity exerts selection on animal morphology, behaviour, sensory systems and life-history. When the resulting adaptations also affect patterns of selective mating, populations may rapidly become reproductively isolated and form new species. This mechanism of species divergence is very powerful in theory, but its importance in the real world has been questioned.

In the cichlid fish of Lake Victoria (East Africa), bright male coloration affects both inter- and intraspecific female mate choice, indicating that sexual selection is important for species differentiation. At the same time, the fish show extensive variation in colour vision, apparently as an adaptation to their diverse visual environments. Possibly, visual adaptation to different light conditions changes female perception of male coloration, such that females that inhabit different light environments will develop different colour preferences.

To investigate the role of visual adaptation in cichlid speciation, I use a combination of field observations (characterising under water light conditions and haplochromine colour diversity across communities) and laboratory experiments (testing the effects of visual adaptation on visual behaviour in foraging and mate choice contexts).

Previous projects