Multi-taxa distribution patterns in a fragmented landscape of Semideciduous Atlantic forest

Background/Question/Methods

The metacommunity concepts assume that the interaction between processes in local and regional scale determine the diversity and composition of local assemblage. Although researches addressing patterns of species composition along environmental gradients have been subject of numerous studies in recent years, spatial variation in species composition for different biological groups in the same patchy landscape has not been addressed. Here, we used an approach that combines evaluation of three elements of metacommunity structure – coherence, range turnover and range boundary clumping – to identify which idealized structure (checkerboard, nested, Clementsian, Gleasonian, evenly spaced, or random distributions) most accurately characterizes empirical metacommunities for six biological groups (ants, algae, amphibian, birds, phanerogams, social wasps ) in 18 forest fragments of the Semidecidual Atlantic Forest in southwestern Brazil. Prior to analysis, matrices were ordered using the primary axis extracted via reciprocal averaging. For each metacommunity, 1000 randomly generated matrices were created using a null model with fixed column and equiprobable row. To determine which factor was associated with the latent environmental gradient for each biological group, Spearman rank correlations were conducted between site scores from the primary axis of correspondence and six descriptors of forest fragments: i) size of forest fragment (ha), ii)  forest area at a radius of 2 Km and  iii) 5 km from the center of the fragment,  iv) forest area functionally connected to other forest fragments through the matrix of 300 m (ha), v) annual precipitation (mm) and vi) forest fragments’ distance from the sea (Km). 

Results/Conclusions

Our results showed that the distributions of ants, birds and phanerogams were nested while distributions of algae, amphibians and social wasps were complex and most consistent with a quasi-Clementsian structure. However, the environmental gradient structuring each metacommunity was depending on biological group: i) social wasps, birds and algae were correlated with forest area at a radius of 2, 5 and 5 km from the center of the fragment respectively, ii) ants with annual precipitation, iii) amphibians with distance from the sea and iv) phanerogams with forest area functionally connected to other forest fragments through the matrix of 300 m. Our results showed that metacommunities are shaped differently depending on the biological group considered even in the same patchy landscape. Differences in dispersal abilities and specie-specific tolerance are considered the main factors contributing to structuring biological groups along different environmental gradients.