Padrões genético-populacionais do “tracajá” Podocnemis unifilis (Troschel, 1848) (TESTUDINES: PODOCNEMIDIDAE) na Amazônia brasileira

Abstract

The yellow-spotted river turtle Podocnemis unifilis is the most widely distributed freshwater river turtle and is found in a diversity of habitats. Associated with natural characteristics of turtles, human action causes a sharp population declines, causing species like P. unifilis to be on the list of animals to be protected by IBAMA. Many aspects of the biology of the species can be determined using molecular genetic analyses. In some rivers of the Amazon basin, rapids and waterfalls limit gene flow of various aquatic and semiaquatic groups, so it is necessary to study the patterns of species especially in places that are targeted for hydroelectric projects. Thus, we analyzed the D-loop region of mitochondrial DNA of 300 adult turtles of different rivers in the Brazilian Amazon basin, determining organizational patterns of genetic variability and evaluating the interference of natural barriers. We measured the number of haplotypes, the number of segregating sites, haplotype diversity, nucleotide diversity, neutrality tests, AMOVA and we constructed a haplotype network. To measure levels of structuring among populations, we inferred the Ф ST fixation index, the number of biological groups in the sample, level of gene flow, Mantel's test, and finally, we estimated natural barriers to gene flow using Barrier program. We found high genetic diversity and restricted gene flow with high levels of structuring between locations. The differences within the Madeira, Tapajós, Trombetas, Xingu and Tocantins-Araguaia rivers are possibly caused by waterfalls and rapids. We define 8 different Management Units: Barreirinha, middle Trombetas River, Tapajós River, upstream of the waterfall of Volta Grande do Xingu River, downstream of the waterfall of Volta Grande do Xingu River, Guaporé River, Tocantins-Araguaia basin and a group of the Amazon floodplain area with other populations. We indicate the use of our data in making decisions to release young in participatory management of project sites of Amazon turtles, in decisions on implementation of construction projects and inspection and seizure of illegal trade in turtles, and underline the importance of studying the species through other molecular markers to assist in the conservation of turtles.