  Ecologists have put forward many explanations for coexistence, but these are
only partial explanations; nature is complex, so it is reasonable to assume
that in any given ecological community, multiple mechanisms of coexistence are
operating at the same time. Here, we present a methodology for quantifying the
relative importance of different explanations for coexistence, based on an
extension of Modern Coexistence Theory. Current versions of Modern Coexistence
Theory only allow for the analysis of communities that are affected by spatial
or temporal environmental variation, but not both. We show how to analyze
communities with spatiotemporal fluctuations, how to parse the importance of
spatial variation and temporal variation, and how to measure everything with
either mathematical expressions or simulation experiments. Our extension of
Modern Coexistence Theory allows empiricists to use realistic models and more
data to better infer the mechanisms of coexistence in real communities.
