Using null models to disentangle variation in community dissimilarity from variation in α-diversity

Β-diversity represents the compositional variation among communities from site-to-site, linking local (α-diversity) and regional (γ-diversity). Researchers often desire to compare values of β-diversity across localities or experimental treatments, and to use this comparison to infer possible mechanisms of community assembly. However, the majority of metrics used to estimate β-diversity, including most dissimilarity metrics (e.g., Jaccard's and Sørenson's dissimilarity index), can vary simply because of changes in the other two diversity components (α or γ-diversity). Here, we overview the utility of taking a null model approach that allows one to discern whether variation in the measured dissimilarity among…