A framework for metacommunity analysis of phylogenetic structure.

It is well known that species evolutionary history plays a crucial role in community assembly. Here, we offer a formal analytical framework to integrate in metacommunity analysis the species' phylogeny with their functional traits and abundances. We define phylogenetic structure of a community as phylogenetically weighted species composition. This is used to reveal patterns of phylogenetic community variation and to measure and test by specified null models the phylogenetic signal at the metacommunity level, which we distinguish from phylogenetic signal at the species pool level. The former indicates that communities more similar in their phylogenetic structure are also similar in their average trait values, which may indicate species' niche conservation for the given traits. We apply this framework to an example from grassland communities and find that traits with significant phylogenetic signal at the metacommunity level exhibit ecological filtering along the resource gradient, but since both mechanisms act independently on traits, niche conservatism is not supported.