PALEOTOPOGRAPHY AND THE DIVERSIFICATION OF FRESHWATER FISHES

One of the two fundamental theses presented by Charles Darwin in his On the Origin of Species (1859) is that all life on Earth shares common ancestry. These phylogenetic relationships are inferred among organismal lineages using homologous phenotypic traits and/or DNA sequences from orthologous genes. Molecular clock methods, which often involve calibration information from the fossil record, offer the ability to convert molecular-inferred phylogenies into estimates of absolute age to common ancestry from the most closely related species to the very most distantly related major branches in the Tree of Life.

Historical biogeography seeks to determine how Earth history events drive geographic isolation and eventual organismal lineage diversification, primarily through the correlation of phylogenetic relationships with the sequence of paleotopographic changes. Earth history events often investigated in historical biogeography include the breakup of supercontinents, the origin and demise of oceanic islands, and the disruption of river drainage courses.

The inference of phylogenetic relationships and their correlation to paleogeography is applied to investigate how changes in topography drive lineage diversification in freshwater fishes in the temperate biodiversity hotspot of eastern North America, and cichlid fishes distributed on West Gondwana landmasses.