Environmental correlates of assemblages of fishes in the Tilostoc River of central Mexico

Abstract

Ordination, correlation, and regression analyses were used to identify trophic and taxonomic distributional patterns of fishes in the Tilostoc River (located west of Valle de Bravo Lake in the Middle Balsas Basin, central Mexico) and associations of these patterns with environmental variables. Nonmetric multidimensional scaling analysis indicated that trophic and taxonomic assemblages corresponded similarly to measured environmental gradients, especially elevation and velocity of currents. We also compared the trophic structure of assemblages of fishes of the Tilostoc River to that of Terreros Creek, a temperate system of similar size and species richness but with a taxonomically different group of species. The two basins were significantly different, indicating strong historical constraint on trophic structure. Our trophic matrix for Tilostoc River was strongly correlated with the taxonomic matrix.