Abstract
Biotic interactions are fundamental drivers governing biodiversity locally, yet their effects on geographical variation in community composition (i.e. incidence‐based) and community structure (i.e. abundance‐based) at regional scales remain controversial. Ecologists have only recently started to integrate different types of biotic interactions into community assembly in a spatial context, a theme that merits further empirical quantification. Here, we applied partial correlation networks to infer the strength of spatial dependencies between pairs of organismal groups and mapped the imprints of biotic interactions on the assembly of pond metacommunities. To do this, we used a comprehensive empirical dataset from Mediterranean landscapes and adopted the perspective that community assembly is best represented as a network of interacting organismal groups. Our results revealed that the co‐variation among the beta diversities of multiple organismal groups is primarily driven by biotic interactions and, to a lesser extent, by the abiotic environment. These results suggest that ignoring biotic interactions may undermine our understanding of assembly mechanisms in spatially extensive areas and decrease the accuracy and performance of predictive models. We further found strong spatial dependencies in our analyses which can be interpreted as functional relationships among several pairs of organismal groups (e.g. macrophytes–macroinvertebrates, fish–zooplankton). Perhaps more importantly, our results support the notion that biotic interactions make crucial contributions to the species sorting paradigm of metacommunity theory and raise the question of whether these biologically‐driven signals have been equally underappreciated in other aquatic and terrestrial ecosystems. Although more research is still required to empirically capture the importance of biotic interactions across ecosystems and at different spatial resolutions and extents, our findings may allow decision makers to better foresee the main consequences of human‐driven impacts on inland waters, particularly those associated with the addition or removal of key species.
Highlights
A long-standing and overarching question in ecology is what governs the geographical variation of biodiversity on Earth (Logue et al 2011)
We hypothesised (H1) that the abiotic environment would be more important than biotic interactions for variation in community composition (D’Amen et al 2018), supporting Grinnellian ideas (Chase and Leibold 2003) that species occurrences are primarily explained in terms of the resistance of biotas to prevailing abiotic environmental conditions
Most non-null partial correlations estimated between beta diversities of each predefined organismal group and environmental distances were positive (Supplementary material Appendix 5)
Summary
A long-standing and overarching question in ecology is what governs the geographical variation of biodiversity on Earth (Logue et al 2011). Recent decades have witnessed a remarkable increase in the number of studies examining beta diversity across multiple geographical and environmental gradients (see Mori et al 2018 for a review). Central to this perspective is metacommunity theory (Logue et al 2011), which has been a useful framework for integrating the abiotic environment, biotic interactions and dispersal events as drivers of biological diversity across spatial scales (Heino et al 2015)
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