The signature of biotic interactions on lake macrophytes differs among seven metacommunities of three continents

Abstract

There is a lack of empirical evidence on how biotic and abiotic mechanisms interact to structure freshwater metacommunities. We explored using Hierarchical Modelling of Species Communities whether consistent species-to-species associations remain after accounting for species’ different responses to environmental and spatial variation in lake macrophyte communities across seven regions. We found that environmental filtering, a concept suggesting that the abiotic environment selects species with similar trait values within communities, was the primary mechanism structuring these metacommunities. Variance explained by environmental features varied from one region to another, showing context dependency. Species functional traits explained a relatively modest proportion of the total variation in species occurrences and species niches; however, environmental features had a statistically significant contribution to individual species traits. Phylogenetic signals were generally weak, and species-to-species associations showed context dependency across study regions. Alien-invasive species showed mostly negative associations with native species, whereas positive relationships between alien-invasive species were also evidenced. Moreover, we did not find any relationship between certain known alien-invasive and native species. Overall, metacommunity research in freshwater ecosystems should more resolutely integrate potential biotic interactions to future investigations to comprehensively understand the interplay between environmental factors, dispersal and biotic interactions in shaping freshwater community dynamics.