Population genetics and conservation strategies for the West Indian manatee (Trichechus manatus Linnaeaus,1758) in Brazil

• Autor(a) principal: LUNA, Fábia de Oliveira
• Data de Publicação: 2013
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UFPE
• Texto Completo: https://repositorio.ufpe.br/handle/123456789/10681
• topic: Genetics population of manatees; Conservation of aquatic mammals; Hybrids between two sirenian species; Inbreeding of manatees in captivity

The West Indian manatee (Trichechus manatus) and the Amazonian manatee (Trichechus inunguis) belong to the mammalian Order Sirenia, classified respectively as critically endangered and as vulnerable in Brazil. Both species have been hunted commercially since the sixteenth century, resulting in a drastic reduction or elimination of manatees in some places. This hunting pressure may have caused isolation of the populations resulting in geographic genetic isolation, with a reduction of their genetic diversity. The objective of this study is to understand the genetic diversity and population structure of the West Indian manatee (T. manatus) in Brazil; verify the existence of hybridization between the manatees T. manatus and T. inungus; define the degree of relatedness of individuals in captivity; and provide strategies for the conservation of the species. In northeastern Brazil, a large number of dependent calves strand on beaches. Many of these calves have been rescued alive and rehabilitated for future release. Previously, the identification of release sites did not take into account the genetic issues. Through this study, it has been possible to identify suitable release sites based on phylogenetic traits of the manatees. The genetic structure of the population was studied using nuclear DNA in the program STRUCTURE, and comparing FST and RST values. On the Northeast coast one population was identified, which is subdivided in two subpopulations. A different genetic population was found in the Northwest of the Amazon River estuary (extreme north of Brazil, Guyana and Venezuelan). Manatees from the Estuary of the Amazon River grouped with Amazonian manatees from the Santarém region to form a third population. A total of four manatee Management Units were identified along the Brazilian coast, which should be treated separately for management and conservation needs. Using a combination of molecular markers (mtDNA and nDNA) and cytogenetic analyses the existence of hybridization between T. manatus and T inunguis was confirmed, although this does not appear to be a frequent occurrence. Some of the dependent calves rescued, and other individuals transferred from irregular captive conditions to the CMA/ICMBio, were kept together and breeding occurred. Maintaining related manatees together can lead to inbreeding. It was possible 29 to establish the degree of relatedness between individuals kept at CMA/ICMBio and verify the extistence of inbreeding. To avoid inbreeding, hybridization, and overpopulation in captivity, it is necessary that males and females be separated immediately, thereby preventing reproduction ex-situ. The present study allows us to establish actions for the conservation of the West Indian manatee. Actions that should be prioritized include: protection and restoration of habitat with the creation and implementation of specific protected areas; creation and maintenance of travel corridors that allow gene flow; reduction and elimination of anthropogenic pressures on the species; stopping pointless reproduction in captivity; designing further studies in the north of Brazil to better understand the hybridization and implement the action plan.