The fish order Characiformes comprises the most important group of freshwater fishes living in Africa and in Central and South America. They have been studied extensively because of their economic importance as food and as aquarium resources (for example, the "tetras"), and because of their remarkable adaptations to numerous kinds of aquatic environments, including the infamous predatory habits of the piranhas. However, the evolutionary relationships among the major families of characiform fishes are poorly understood, and morphological characters alone promise little help in resolving the matter. Faculty advisor Axel Meyer will assist graduate student Guillermo Orti in an extensive molecular systematic survey of mitochondrial DNA variation in representative samples of the major characiform groups. The amount and kind of mutational differences in mitochondrial DNA between fish species indicate relative degree of genealogical relationship, and thus provide data to infer the phylogeny of these lineages. Insight into the evolutionary history of this species-rich group of fishes will in turn help in understanding the geographical diversification between African and South American faunas following the geological breakup of Gondwana.
