Filogeografia e Conservação de Paratrygon aiereba Dumeril (Chondrichthyes: Potamotrygonidae) na região Amazônica

Abstract

Phylogeography is a branch of biogeography that investigates the processes that rules the geographic distribution of genetic lineages. It deals with the spatial distribution of alleles which phylogenetical relationships is known or can be estimated. Thus, through phylogeographic studies its possible to investigate population processes and regional models that interferes on diversity and distribution of populations. Phylogeography studies can also generate a basis for conservation studies because species diversity represents the amplitude of evolutionary and ecological adaptations in relation to certain environments. For this, in phylogeographycal studies, the historical tool commonly used is mitochondrial DNA (mtDNA), because it allows genetic studies among populations, species and higher taxonomic levels. Stingrays are part of Chondrichthyes Class, cartilaginous fishes, Elasmobranchii subclass. The species group of Elasmobrachii, that, in fact, comes from sweet water, have a complete lifecycle in continental waters, are placed on Potamotrygonidae family, and occurs exclusively on the neotropical region, México and South America. Potamotrygonidae family is composed by one monophyletic clade with three genera: Paratrygon Dumeril, Potamotrygon German and Pleisiotrygon Castello & Thorsan. Most part of its species have a restricted distribution to one unique basin or fluvial system. Just Potamotrygon motoro, Potamotrygon orbignyi e Paratrygon aiereba species are found in more than one basin. The present study aims to investigate the genetic structure of Paratrygon aiereba in six rivers from Amazon region: Rio Negro, Solimões-Amazonas system, Tapajós, Xingu, Marajó Island and Araguaia. For that, the ATPase fragment was used as molecular marker. The results showed that the populations of this specie are structured inside each river, with restrict gene flow, or even without gene flow, xii showing a positive correlation between genetic and geographic distances. It was also observed that genetic variability is very low at Rio Negro populations, Solimões-Amazonas system and Xingu River. The Rio Negro is very well known for its ornamental fishery and at Solimões-Amazonas system these animals are used as a protein source and suffer commercial fishery. At Xingu River they are geographically isolated below Belo Monte waterfalls. All these factors, therefore, can influence the low genetic diversity in P. aiereba. Considering that, conservation strategies need to be taken in local scales, for each river, instead of using higher regional scales.