Abstract
Understanding biodiversity is at the heart of biology, and crucial for effective nature conservation. Nevertheless, 150 years after Darwin?s book, the origin of species remains a biological enigma. Theory predicts that speciation is easy when ecological adaptations have immediate effects on selective mating. However, such mechanisms are considered to be rare in the real world. Here, I argue that this assumption is premature, and propose an experimental investigation of the idea that interactions between natural and sexual selection can in fact drive speciation in nature. The cichlid fish of Lake Victoria (East Africa) are a textbook example of explosive speciation: hundreds of species have evolved in a very short time. Female preferences for different male colours maintain isolation between species. In my previous work, I found correlations between female colour preferences, natural light environments, and colour vision. This inspired the hypothesis that 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. Such a tight link between ecological adaptation and mating behaviour may explain the astonishing speed of cichlid speciation, and could contribute to colour diversity in many other systems as well. I will test the correlational evidence by an experimental approach that exploits recent advances in visual genomics and perceptual modeling. This allows quantitative analyses at the full range of biological organisation: from pigment genes and pigment composition in the eye, to individual behaviour in controlled light conditions and biodiversity dynamics in natural communities. Few systems allow such a throrough and interdisciplinary investigation of an evolutionary hypothesis. My results will provide much-needed insights in the interplay between natural and sexual selection during speciation, and contribute to sustainable management of the economically important but severely threatened Lake Victoria ecosystem.
Netherlands