This DDEP proposal seeks support for PhD candidate Stuart C. Willis for research on species formation in Brazil. Mr. Willis will be working under the guidance of both Dr. Guillermo Orti (University of Nebraska-Lincoln) and Dr. Izeni Pires Farias (Universidade Federal do Amazonas, Manaus, Brazil). The PIs have a novel perspective on species formation based on the growing recognition that hybridization, that is the process of combining different varieties or species of organisms to create a hybrid may lead to new species and thus applies to animals and not just to plants and bacteria. They plan to test their theory on species rich faunas such as the Neotropical freshwater fishes to classify and study previously unidentified hybrid species. The discovery and cataloguing of unique genetic lineages is particularly critical for setting sustainable management and conservation priorities of fishes which are considered important commercial food and recreational resources.