A ictiofauna da Ecorregião Tocantins-Araguaia: diversidade, redes de pesquisa e construção do conhecimento

Abstract

Fish are the most diverse group of vertebrates and they have most of their diversity in freshwater environments. The Neotropical region has the most diverse freshwater ichthyofauna in the world and in this context the Amazon basins are very representative. The Tocantins-Araguaia ecoregion, which corresponds to the part of the Tocantins-Araguaia basin upstream of the Tucuruí Dam, is located on the eastern border of this drainage and although its rivers are not direct affluents of the Amazon River, they have an essentially Amazonian ichthyofauna with a high rate of endemism. In this context, this work aimed to quantify the number of valid species occurring in the Tocantins-Araguaia ecoregion; elucidate the network of researchers and institutions that described species with type locality within the ecoregion; and understand the historical process of description of species with type locality within the ecoregion. For this, a bibliographical survey was carried out in order to register the species occurring in the ecoregion; the analysis of networks through specific software; and the association between the type locality and the year of description of the species to understand the historical process of descriptions of species from the ecoregion. This research revealed a greater ichthyological diversity than those previously noted for the study area by regional works. The first species of fish recorded for the ecoregion date back to the first descriptions made by Linnaeus in 1758, but it was in the 19th century that the first species with a type locality within the ecoregion began to be described. The collaboration networks between researchers and institutions that study the ecoregion's ichthyofauna were initially formed by foreigners and they were gradually replaced by an international network currently represented mainly by Brazilian researchers and institutions, however, foreign collaboration was maintained. The first descriptions of species with a type locality within the ecoregion were the result of large foreign expeditions that included the participation of naturalist-travelers who explored inhospitable regions of the interior of Brazil. Finally, the results reinforce the need for conservation actions that can contribute to the conservation of the diversity of this ichthyofauna and public policies that encourage, strengthen and value the group's knowledge so that decisions regarding the use and occupation of aquatic environments consider the occurrence, distribution and habitats necessary for this taxonomic group.