Adaptive radiation, speciation, and reproductive isolation in African weakly electric fishes (genus Campylomormyrus, Mormyridae, Teleostei)

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The endemic African mormyrids comprise the single largest group of electric fishes worldwide. Their electric organ discharge (EOD) is age, sex, and species specific. We aim at evaluating whether differences in EOD play a key role as prezygotic isolation mechanisms during speciation. Then, we hypothesize that EODs should be particularily divergent among morphologically and genetically similar species. We chose the Campylomormyrus numenius species complex as a model taxon because it contains a still unknown number of morphologically similar species with strikingly divergent EODs. We will combine molecular analysis (mitochondrial cyt b gene, several unlinked nuclear loci) with electrophysiology (electric organ discharge in relation to sex, age, morphotype, and genotype). The significance of EODs for species specific mate recognition will be assessed in mate choice experiments. During our preliminary work, we (1) develped the necessary molecular markers, (2) established the EOD assessment, and (3) optimized the laboratory maintenance of live Campylomormyrus specimens. The ultimate goal of this project is to better understand the relevance of weak electricity in the radiation of African electric fish.