The phylogenetic relationships among species within an area are commonly used to understand the ecological and evolutionary drivers of community assembly. While it is known that these patterns may change with phylogenetic scale, it is currently unknown whether these patterns show a phylogenetic scaling relationship, that is, whether they change predictably as phylogenetic scale changes. Recent work has shown that mammalian diversification shows a phylogenetic scaling relationship, and it has been hypothesized that the assembly processes often attributed to community phylogenetic patterns may change with phylogenetic scale, so we may expect that community phylogenetic patterns also show a phylogenetic scale dependence. Here, we ask whether relationships between phylogenetic structure and climate depend on phylogenetic scale (clade age). We calculate the relationships between New World mammal phylogenetic structure and climate across the nodes of a phylogeny while keeping spatial grain and extent constant. We calculate phylogenetic structure using two metrics that target different phylogenetic grains: PSV, which is focused on deeper branching events, and PSC, which focuses on branching events closer to the tips of a phylogeny.
Results/Conclusions
We find that associations between community phylogenetic structure and climate show strong phylogenetic scale-independence: as phylogenetic scale (clade age) changes, there is no clear trend in the strength or direction of the correlation between climatic predictors and community phylogenetic structure. These results are consistent with recent work in plant communities showing that changing phylogenetic scale can substantial impact on inferred assembly mechanisms. Interestingly, however, recent work on diversification rates of Mammal clades does show a predictable association with phylogenetic scale, suggesting that ecological context may obscure the effects of diversification rates on community phylogenetic patterns. This work suggests that conclusions made using community phylogenetic patterns for a given clade will often not apply to that clade’s parent clade or daughter clades. This work supports recent calls in the literature to develop a more refined body of theory within the field of community phylogenetics.