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Title: Estrutura genética de Podocnemis expansa (Testudines - Podocnemididae) no alto Rio Madeira e sua implicação na avaliação do impacto das hidrelétricas de Jirau e Santo Antônio (Rondônia, Brasil)
Authors: Vieira, Camila Paiva
metadata.dc.contributor.advisor: Ribas, Camila Cherem
Keywords: Barreiras artificiais
Genética de populações
Tartaruga da Amazônia
Issue Date: 25-May-2015
Publisher: Instituto Nacional de Pesquisa da Amazônia - INPA
metadata.dc.publisher.program: Genética, Conservação e Biologia Evolutiva - GCBEv
metadata.dc.description.resumo: Podocnemis expansa is the largest Amazonian turtle and is distributed throughout the Amazon, Orinoco, and Tocantins/Araguaia river basins. Its distribution pattern is metapopulational, with differences in genetic structure among sub-basins, but maintaining widespread connectivity. Strong white-water rapids are among the natural barriers to aquatic vertebrate dispersal. In the upper Madeira River, one of the main tributaries to the right margin of the Amazon, a sequence of 18 rapids constitutes an impermeable or semi-permeable barrier for several species, from fish to caimans and dolphins. P. expansa were found in between all Madeira rapids surveyed for this study, but capture-recapture was not suitable to estimate gene flow among the rapids in this species. Mitochondrial DNA control region and five nuclear microsatellite loci were analyzed to estimate genetic diversity and connectivity of P. expansa among the rapids, and in relation to other parts of the specie’s distribution area, as well as possible recent population bottlenecks. No genetic evidence was found of a recent decrease in effective population size, despite the species being known to suffer heavy overexploitation in the region since the XIXth century. The most common haplotype througout the species` distribution area also occurred frequently in the upper Madeira, supporting the panmictic structure of the species in the Amazon basin. Three haplotypes were recorded only in the study area, one of them being very abundant among the sampled individuals. The microsatellite loci indicated only one grouping for the upper Madeira region, while mitochondrial DNA indicated five groups, which mixed up indistinctively along the inter-rapids stretches surveyed. Genetic diversity was higher in the upper Madeira than in the Guaporé River, a tributary located upstream from the rapids, suggesting some level of gene flow restriction between the two areas. However, the results do not support a barrier effect of the rapids for P. expansa. The recent construction of two hydropower dams in the upper Madeira River, on the other hand, is very likely to have formed impermeable barriers for P. expansa, interrupting gene flow between turtles in the upland part of the Madeira sub-basin and the rest of the Amazon basin. Until 2020, thirty large hydropower plants will be constructed in many of the main tributaries of the Amazon basin, which will compromise the connectivity of P. expansa on a geographical scale equivalent to a large proportion of its Brazilian distribution area. Mitigation measures for affected P. expansa in existing hydropower dams are limited to the management of downstream egg-laying sites and headstarting programs. However, 11 the scenario laid out by the hydroenergetic development in the Brazilian Amazon requires that mitigation measures include the preservation of connectivity between turtles up and downstream from the dam, in order to ensure the genetic integrity of this ancient and emblematic species.
Appears in Collections:Mestrado - GCBEv

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