Relações entre condições ambientais, filtros espaciais e estratégias de dispersão na estruturação de metacomunidade de invertebrados aquáticos em ocos de árvores

Abstract

Local environmental factors and spatial factors can act in the structuring of metacommunities, but the role of each of these factors and the role of strategies of organism dispersal in this structuring is still controversial. We used data from 41 tree holes to evaluate the role of local and spatial factors in the general metacommunity structuring of groups characterized by active and passive dispersal. We expected that local environmental conditions would explain the largest portion of variability in tree hollow metacommunity structure and that, considering strategies of organism dispersal, an increased importance of spatial variables would be detected for organisms with passive dispersal when compared to those with active dispersal. The most obvious result from our study is the large amount of unexplained residual variation. In general, no significant effect of either environment or space was observed on invertebrate community structure, with the partition of variance revealing that the largest portion of variability was not explained (99% residual). With regard to the active dispersal group, there was also no significant effect of these predictors, revealing 99% unexplained residual variation. In the passive dispersal group, most of the variability was also not explained; however, the portion that corresponds to the environment together with space significantly explains 18% of the variation. Discarding possible sources of uncertainty in our data, we believe that this study demonstrates that a single model is not sufficient to explain patterns of natural metacommunities, and our understanding of the processes and mechanisms that are represented by the high residual variation remains unclear in these tree hollow metacommunities.