Metacomunidade de anuros dos campos sulinos, Brasil: uma abordagem em macroescala sobre padrões neutros e de nicho

Abstract

The metacommunity theory was proposed as a theoretical tool which helps to distinguish the processes involved in the generation and maintenance of patterns in distribution, richness, abundance and species composition along the environment on different spatial scales (local, regional and among communities). Two main theories have been used to evaluate how processes interact to organize the patterns observed in nature: neutral and niche. The evaluation of the patterns in a metacommunity can be accomplished by using taxonomic entities or by combining functional attributes and the phylogenetic relationships among species. This thesis aimed to assess what are the processes and patterns governing the metacommunity of anurans of the ‘Campos Sulinos’. For this, we use the theoretical perspective of the neutral and niche theories, using species richness, abundance and taxonomic composition as answer variables, as well as the functional attributes and the phylogenetic relationships among species. The study was conducted in the ‘Campos Sulinos’, which are included within the Pampa and Atlantic Forest biomes. Samples were collected in the austral spring of the years 2011-2013. Adult frogs were collected by the method of ‘survey at breeding sites’, and the tadpoles by using a long-handled dip net with metal mesh of three mm². Additional data of species richness were obtained through occasional encounters. We recorded 47 species of frogs, belonging to six families. The richness, abundance and taxonomic composition were explained by climatic and landscape variables in local and regional scales. The grassland typologies and physiographic regions differed in richness, abundance and species composition. The structure of anuran metacommunity registered in water bodies was explained by local environmental descriptors by landscape descriptors and by spatial filters. Thus, both neutral (spatial filters: 17%) and niche-based processes (local descriptors: 5%; landscape descriptors: 4%) affected the metacommunity structure; however, neutral processes were dominant. Both patterns of convergence and divergence related to environmental filter were found in the metacommunity. The proportion of remaining grassland was not responsible for the phylogenetic pattern recorded in the metacommunity. We found phylogenetic signal in the species pool level, but not for the metacommunity. The pattern registered for the metacommunity of frogs of ‘Campos Sulinos’ is complex, given that the metacommunity responded to both neutral and niche-based processes. Anurans can only disperse in the environment if the grassland matrix is conserved, since monocultures (soy, rice and afforestation) can become barriers to specialist species. Therefore, priority should be given to the connection between grassland remnants, because the connection can facilitate gene flow and prevent population declines in areas already converted. In addition, due to the dependence of frogs to environmental conditions, should be prioritized the conservation of grassland areas with conditions for the formation of permanent and temporary water bodies. These actions will contribute to the conservation of the taxonomic, functional and phylogenetic patterns of the metacommunity of frogs from the ‘Campos Sulinos’.