Affiliation: College of Arts and Sciences, Curriculum in Environment and Ecology
Ecologists define a community as the set of species successfully reproducing and using resources in a shared space. In lieu of a species list, the subset of temporally persistent core species may more appropriately fulfill this definition. Analyses carried out in communities that support low proportions of core species may violate assumptions about the definition of a community, and so poorly align with ecological predictions. We used bird time series data to calculate the proportion of core species across a gradient of scales, to investigate potential generalities in this pattern, and to use these generalities to address discrepancies on drivers of community assembly. We found that the proportion of core species in an assemblage increased in a positive curve with scale and decreased with high environmental heterogeneity (e.g. elevation, vegetation coverage). Communities with high heterogeneity and low proportions of core species were likely dispersal-driven, not resource-limited.