Taxocenose de serpentes associada a ambientes aquáticos em três ecossistemas de roraima, áreas de altitude, mata e lavrado (squamata, serpentes)

Abstract

In studies that comprise species biogeography, the use of naturally delimited areas (e.g. ecosystems and biomes) is consensual. This enables a better understanding of the patterns developed by the taxa, greater reliability in the data obtained, in addition to more efficient interpretations of the biological differences of an animal group across localities. Roraima is inserted in a region composed of several naturally delimited areas, such as the Guianas Shield. In this area, there are three ecosystems with greater representation in Roraima: the forest regions, the savannahs (regionally called as lavrado) and the altitude areas. In this sense, the aim of this study was to verify the possibility of an ophiofauna endemic to this geological formation, as pointed out by some studies. The guiding hypothesis focused on the arguments that there is a fauna endemic to this Shield. A richness of 56 species of snakes distributed in seven families was observed: Leptotyphlopidae, with 1 genus and 1 species; Aniliidae, also with 1 genus and 1 species; Boidae, with 4 genera and 5 species; Colubridae, with 9 genera and 14 species; Dipsadidae, with 17 genera and 26 species; Elapidae, with 1 genus and 4 species and Viperidae, with 3 genera and 5 species. The taxocenosis occurs heterogeneously with other Brazilian morphoclimatic domains and, although the 56 occur in this portion of the Guianas Shield, only 19 are restricted. Therefore, it is concluded that there is no endemic ophiofauna of the Guiana Shield in the geographic unit analyzed in this study. Regionally, the species are homogeneously distributed, transiting between ecosystems, representing a predominance of the Amazonian pattern of faunal composition, with a prevalence of species in the forests. Regarding the natural history, for microhabitats, six guilds are occupied by species, with prevalence of terrestrial, followed by arboreal, semi-arboreal, semi-fossorial, aquatic and fossorial. For the diet, the pattern is heterogeneous, with an abundance of 18 food items, prevailing the guild of saurivorous species, followed by batrachophagous and predation of mammals. Analyzing the overlapping of niches by species, an intermediate index was found for microhabitat and low for diet, evidencing the role of ecological factors in structuring these biotic communities. Historical factors were better visualized at the family level, although it is not possible to conclude on prevalence. Thus, it is concluded that the taxocenosis is structured from the interaction of ecological and historical factors.