Padrões de distribuição da ictiofauna na Sub-Região Chaco, Região Neotropical (sensu Morrone, 2014)

Abstract

Geographically, the greatest diversity of freshwater bony fish occurs in the Neotropical Region. Despite the richness of the neotropical ichthyofauna, studies about its origin and history are scarce. Overall, the recognized biogeographic patterns of freshwater fish are used only to complement patterns found in terrestrial taxa or are used to generate models to explain global biogeographic patterns. Futhermore, in general, biogeographical studies accomplished with fishes exclude biological aspects. Although the history of neotropical rivers and lakes is recent from the geochronological point of view, they have unique biotic complexities, which include an outstanding ichthyological diversity. In order to reconstruct and to understand the history of isolation, divergence and diversification of ichthyofauna, different tools of Historical Biogeography can be used, specifically Panbiogeography. This method emphasizes the geographic spatial dimension of biodiversity, allowing a better understanding of evolutionary patterns and processes. Through Panbiogeographical Track Analysis, it is possible to relate the geological history of a region to the distribution of specific or supraspecific taxa today. There are three basic concepts: individual track, generalized track and node. The first is an estimate of the distribution of a taxon; the second represents the current distribution of ancestral biota which have been fragmented; and the last is considered an area of great geobiological complexity. The aim of this study was to recognize distributional patterns of freshwater bony fish from Chacoan Sub-region. The results presented 38 generalized tracks and 4 nodes. The families of Characiformes, Siluriformes, Gymnotiformes and Cyprinodontiformes show distributional patterns corroborated by the patterns of other taxa. Also, these patterns are related to the geological history of the Chacoan Subregion.