Comparação filogeográfica de duas espécies de peixes com ampla distribuição na América do Sul: problemas de delimitação de espécies

Abstract

The neotropical ichthyofauna corresponds to nearly 25% of the total number of fish species in the world. This diversity is mainly due to several endemic taxa in the various watersheds. Within these species a few nominal taxa show a large distribution being known in the Amazon Basin as well as in Paraná-Paraguai Basin. The validity of these species is of great evolutionary importance, in view of the fact that these watersheds have little or no contact since the upper Miocene, approximately 10 million years. The aim of this study is to analyze two complex of neotropical species, belonging to different families (and orders), Potamotrygon motoro and Synbranchus marmoratus, both with distribution in these two important basins. For this study we used both morphological and molecular data. Our purpose is to lead a phylogeographic analysis, to understand the evolution of the groups as well as the evolutionary history of these taxa within the drainages with which they are associated. Our results show that both species complexes represent a group of cryptic species. The species from the Amazon basin are diffrent from those of the Paraná Paraguai Basin. Within the Paraná-Paraguai Basin, the Paraguai River shows more philogetic affinities with the Amazon Basin indicating thus close and more recent relationship.