Gradiente latitudinal de riqueza de espécies de formigas em cerrado: regra de Rapoport e efeitos da produtividade e heterogeneidade

• Autor(a) principal: Ribas, Carla Rodrigues
• Data de Publicação: 2006
• Tipo de documento: Tese
• Idioma: por
• Título da fonte: LOCUS Repositório Institucional da UFV
• Texto Completo: http://locus.ufv.br/handle/123456789/855
• topic: Formiga; Ecologia do Cerrado; Diversidade biológica; Ecossistema; Modelos nulos; Ants; Ecology of Cerrado; Biological diversity; Ecosystem; Null models; CNPQ::CIENCIAS BIOLOGICAS::ECOLOGIA

The latitudinal gradient in species richness is a well recognized pattern for several taxa. Although many hypotheses have been proposed to explain this gradient some of them are described as more relevant, such as those related to ambient energy, habitat heterogeneity, evolutionary time and mid-domain effect. The aim of this thesis was to test the existence of the latitudinal gradient in arboreal ant species richness at Cerrado, as well as to test explanatory hypothesis for the pattern found. In the first chapter we proposed a method that allowed testing the Rapoport effect in altitudinal and latitudinal distributions and in distributions that are restricted by the sampled area. We re-analysed 55 distributions published in 39 scientific papers and observed several patterns of correlation between range size and midpoint, few of them showing a Rapoport effect. Most statistical methods used up to now to test the Rapoport effect were not able to distinguish between stochastically and deterministically generated patterns, therefore the Rapoport effect should not be considered as a pattern in global ecology. In the second chapter the aim was to test the existence of the latitudinal gradient in arboreal ant species richness at Cerrado and the hypotheses that this gradient was correlated to habitat productivity and heterogeneity at different spatial scales. We observed an increase in species richness with latitude, a reverse latitudinal gradient from that observed in the scientific literature. The environmental variables analysed in this study did not explain the variation in species richness. Probably, processes acting at local spatial scales did not scale up to larger scales. In the third chapter we tested the existence of the mid-domain effect and the Rapoport effect using null models. We found a larger species richness than expected by the mid-domain effect at higher latitudes and instead of the Rapoport effect we observed larger ranges sizes than expected by null assumptions at the boundaries of the domain. Other hypotheses, such as the Cerrado geographical distribution and the evolutionary history of ant species, should be tested as the cause of the reverse latitudinal gradient in arboreal ant species richness at Cerrado.