Padrões espaciais e temporais na amplitude de nicho climático de vertebrados terrestres

• Autor(a) principal: Silva, Helen Rosa da
• Data de Publicação: 2015
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Repositório Institucional da UFG
• Texto Completo: http://repositorio.bc.ufg.br/tede/handle/tede/5527
• topic: Vertebrados terrestres; Nicho ambiental; Amplitude de nicho; Conservação filogenética de nicho; Sobreposição de nicho; Terrestrial vertebrates; Climatic niche; Niche breadth; Phylogenetic niche conservatism; Niche overlap; CIENCIAS BIOLOGICAS::ECOLOGIA

Understanding how species are distributed across space and what determines where they live is one of the oldest goals in Ecology. The concept of niche is very closely related to this goal. In fact, environmental variables are frequently used to predict the potential distribution of species. Niche amplitude is an important concept which helps us to understand which part of the available environmental space each species occupies, and how much of their niches overlap. Here we used a measure of niche amplitude based on the minimum and maximum tolerances of terrestrial vertebrates (except reptiles) for each variable related to climate. We calculated a single measure of niche amplitude for each species by considering together all chosen environmental variables. We used this number to first investigate the presence of latitudinal gradient in niche amplitude across the study area, which comprised the whole terrestrial globe. There is a significant correlation between niche amplitude and latitude for Old World birds. Second we tried to identify some phylogenetic structure in niche amplitude for birds. For this goal, we calculated the pair-wise niche overlap, and then compared the degree of overlap with pair-wise phylogenetic distances. We found no relationship between niche overlap and phylogenetic distance. We conclude that the absence of phylogenetic signal in niche overlap is due to the high dispersion capability of birds in general. If species have a high geographic range, they consequently have high niche amplitude, and therefore high overlap rates. Finally, we found a clear tendency of positive local spatial autocorrelation in mean niche overlap, as neighbor cells tend to show similar rates of niche overlap between species.