Metacommunity structure analysis reveals nested patterns in deconstructed macroinvertebrates assemblages

Abstract

Understanding processes driving patterns of species distribution anddiversity is one of the main objectives of community ecology. The aim of our study was to evaluate the spatial variation in assemblage compositionof stream-dwelling macroinvertebrates and identify which factors (e.g. water quality,land cover) are the most important drivers. We applied the elements of the metacommunity structure approach on a dataset of 38 communities from the Futaleufú basin in northwestern Patagonia. To better understandassemblage variation, we deconstructed our macroinvertebrate dataset into differenttaxonomic and trait groups. We then identified the most influential factors drivingcommunity composition using random forests. We found that half of our datasets (i.e. macroinvertebrate groups) exhibited a nestedstructure with clumped species loss, while the other half showed a quasi-nested patternwith either clumped or stochastic species loss. Overall, water quality was the most important driver of community variation,although climate, geography, and land cover were more or less relevant in particularcases. We found differences in the relative importance of the selected explanatoryvariables among datasets. This would suggest that different components of the macroinvertebratecommunity respond differently to environmental factors. Our findings could be of value for conservation planning, as they suggestthat preserving the most species-rich streams would, to some extent, guarantee theconservation of the entire species pool.