Phylogenetics of Pimelodine Catfishes: Exploring the Temporal and Geographical Contexts of Neotropical Fish Diversification

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0089612Lundberg With ichthyological colleagues from Argentina, Brazil, France, and Venezuela, Dr. John Lundberg of the Philadelphia Academy of Natural Sciences is studying the systematics, evolution, and biogeography of the 90 or so species of "tiger stripe" catfishes of the family Pimelodinae of South America. They are a morphologically and ecologically diverse group of highly valued food fishes that range throughout the vast river basins of eastern South America, including the Amazon, Orinoco, and Parana drainages, with species also known from trans-Andean rivers. All 31 described genera in the family will be sampled, with the help of South American colleagues, and the expected 70-80 species thus acquired will be analyzed for DNA sequences from mitochondrial and nuclear genes, for the construction of phylogenetic trees from comparisons of the mutational differences among species. Morphological studies of these samples and of museum collections will complement the molecular phylogenetic analyses, and French and South American colleagues will also add studies of the fossils for this group, of which 20 are currently known, from deposits dated back to Eocene times but suspected to extend back to the Cretaceous. The dated phylogeny of pimelodine catfishes will be integrated with biogeographic data and reconstructions of the history of South America's large rivers and basins. The temporal patterns and rates of diversification within subclades of these fishes, and their time sequence relationships with Earth history events, will provide tests of suspected causal agents in South American biotic evolution. Significant components of the research involve colleagues from Argentina, Brazil, France, and Venezuela, many of whom will travel to Philadelphia for focused work sessions to integrate the molecular, morphological, and paleontological information.