Cooperative Fish and Wildlife Research Units Program: South Carolina
Education, Research and Technical Assistance for Managing Our Natural Resources

In a metacommunity context, beta diversity is driven by the interplay between abiotic factors and dispersal as represented by spatial distance among communities. Most existing studies have considered only ‘natural’ abiotic factors and have ignored anthropogenic factors such as land cover change and pollution. Most studies have focused only on taxonomic beta diversity, and few have considered functional or phylogenetic beta diversity. Including anthropogenic factors and multiple dimensions of biodiversity may explain additional variation in beta diversity, providing new insight into how metacommunities are structured across the landscape. In this study, we used a 350 site stream fish abundance dataset from South Carolina, USA to quantify variation in beta diversity explainable by dispersal, as well as natural and anthropogenic abiotic variables. We investigated metacommunity drivers along three spatial delineations by breaking up the dataset into a metacommunity at the whole state level, two geomorphologically distinct metacommunities of the upstate and lowlands, and four natural watershed metacommunities. Within each of these metacommunities we calculated taxonomic, functional, and phylogenetic beta diversity and used variation partitioning to determine explained variation. We explained 25-81% of beta diversity for stream fish metacommunities. We observed differing importance of spatial, natural, or anthropogenic factors based on the spatial delineation and diversity dimension. We detected distinct structuring of stream fish communities in South Carolina occurring between the upstate and the lowlands. When accounting for the geomorphic differences the fall line creates, we observed a significant anthropogenic signal in the upstate and lowland metacommunities. Spatial, environmental, and anthropogenic factors explained slightly more variation in beta diversity for the taxonomic dimension compared to the functional and phylogenetic dimensions. Our study highlights the importance of including anthropogenic factors when trying to determine mechanisms for stream fish community structure and the significance of spatial delineation in how researchers interpret their results.