Meeting Abstract
The freshwater fauna and hydrography of the United States has been the subject of intense study for more than a century, resulting in an abundance of data concerning the environment and composition of these freshwater communities. We harnessed existing species distribution and phylogenetic resources and joined them with a novel body shape dataset for more than 900 species of freshwater fishes native to the contiguous United States to determine how the spatial distribution of species richness relates to morphological and phylogenetic diversity, and to speciation rate. Species richness of freshwater fishes in the United States follows the drainage patterns of major river basins, with the most diverse communities in the lower Mississippi River basin and southeastern Appalachia. Analysis of phylogenetic diversity revealed a similar pattern, with a small number of phylogenetically over-dispersed communities localized to the Mississippi delta and the southern Atlantic coast. Morphometric diversity was highly correlated with phylogenetic diversity. Although species richness is highest in the eastern half of the country, speciation rate was highest in the west. These distributions suggest exogenous geographic controls on the distribution of species richness and speciation rate.
