Dimensionality of community structure: phylogenetic, morphological and functional perspectives along biodiversity and environmental gradients

Abstract

Biodiversity is a complex and multidimensional concept that characterizes variation of life on Earth. Nonetheless, most studies have examined only a few, if not just one, dimension in isolation. Herein we conduct analyses that explicitly incorporate correlations among multiple dimensions of biodiversity by characterizing morphological, phylogenetic, and functional structure of bat communities from Atlantic Forest of South America and examine degree of redundancy among these sets of descriptors. Second, we examine dimensionality (i.e. number of orthogonal dimensions) of community structure by quantitatively determining if these different sets of descriptors correspond to unique dimensions. We assess if dimensionality measured from empirical communities differs from that based on communities randomly assembled from a regional species pool. Finally, we examine whether different indices of community structure respond differently to environmental gradients spanning Atlantic Forest. We find that Atlantic Forest bat communities are highly variable in terms of morphological, phylogenetic, and functional structure. Different sets of community structure indices exhibited substantive correlations. Accordingly, dimensionality was lower than the set of six different descriptors or even the three different biological dimensions represented. Nonetheless, observed dimensionality was greater than that expected from a null model of assembly. Only abundance‐based indices of phylogenetic structure exhibited significant environmental gradients. Temperature seasonality was the strongest predictor of phylogenetic structure, with overdispersed communities characterizing more seasonal environments and underdispersed communities occurring in areas of lower variation in temperature. Dimensionality of community structure is low with phylogenetic structure exhibiting the strongest patterns, probably because phylogeny reflects many different ecological aspects of the phenotype that are not restricted to just one index of structure. Temperature seasonality is an important determinant of phylogenetic structure of bat communities in Atlantic Forest. This research helps us to better understand the factors underlying the distribution of biodiversity, which is increasingly important for endangered ecoregions such as Atlantic Forest.