Diversidade genética e estrutura populacional do lobo-guará (Chrysocyon brachyurus)

• Ano de defesa: 2009
• Autor(a) principal: Rodrigues, Manoel Ludwig da Fontoura
• Orientador(a): Eizirik, Eduardo
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Pontifícia Universidade Católica do Rio Grande do Sul; Porto Alegre
• Palavras-chave em Português: ZOOLOGIA; LOBO GUARÁ; GENÉTICA ANIMAL; GENÉTICA POPULACIONAL
• Link de acesso: http://hdl.handle.net/10923/5422

The maned wolf (Chrysocyon brachyurus) is the largest species among the Neotropical canids. Its distribution, morphology, ecology and behavior are closely associated to open vegetation environments, especially the Brazilian Cerrado. This savanna-like biome is a large and complex environment, presenting highly heterogeneous vegetational composition and many geographic elements, such as rivers and mountains. Moreover, this is one of the most human-disturbed biomes in South America, undergoing a high rate of habitat loss and fragmentation. These natural and human-induced factors can lead to different degrees of population structuring of native fauna and flora, depending on ecological and behavioral characteristics of each species. A broad investigation of such patterns is justified, once it is very important in terms of conservation to know possible historical geographic subdivisions of a species, and/or to identify processes of population isolation caused by humans. Once the maned wolf presents many ecological interactions with other Cerrado-dwelling species, it can be considered a keystone species in this ecosystem, which highlights the need to characterize its population structure in the context of adequately conserving and managing the Cerrado biota. For such purposes, molecular markers are a widely utilized tool, and the associated analytical methods are becoming increasingly broad and robust. Thus, this study aimed to investigate the population structure of the maned wolf and to analyze it in the context of the species’ natural history, through the utilization of fast evolving molecular markers that allow inferences on even recent demographic processes.To do that, tissue samples of 144 maned wolves were obtained through the capture of free living animals, captive animals with known geographic origin and roadkilled individuals. Four local populations were sampled in addition to individual collection from many geographic points, resulting in a broad coverage of the species’ distribution. The individuals were genotyped for 14 microsatellite loci, originally developed for the domestic dog and selected for use in this species after an initial screening for amplification efficiency and polymorphism. Analyses were performed to assess genetic variability, population pairwise Fst and Rst, structure analyses with the software STRUCTURE, and demographic tests to check for bottleneck events, population expansion and effective number of individuals (Ne). The diversity levels verified were quite high (mean He = 0. 75) when compared to other canid species. Furthermore, no clear-cut population subdivision was detected, leading to the conclusion that the maned wolf exists as an almost panmictic population throughout a large portion of its distribution. The results of the demographic analyses corroborated previous analyses based on mtDNA data that had inferred a population expansion in this species, and Ne estimated numbers were high. Jointly, these results are compatible with a scenario where maned wolves underwent a population growth in the last few thousand years, maintaining a large number of individuals since then and not presenting any geographic subdivision.Lack of population structure can be, at least in part, explained by the generalist dietary habits and the great dispersal capability of the maned wolf, also implying that so far the anthropic habitat matrix has been permeable to a certain degree for the individuals of this species. However, habitat loss and fragmentation cannot be discarded as a threat for the maned wolf. The isolation process can be too recent to be detected even with microsatellites, and the still large effective size of regional populations may also delay the ability to detect ongoing processes of genetic fragmentation. In case such process continues and becomes even more intense, our present data set should provide a baseline for comparison with future genetic assessments of the maned wolf, allowing the detection of population-level trends of loss of variation and human-induced geographic differentiation.