An important issue in the study of biodiversity is the extent to which global patterns of
species richness reflect large-scale processes and historical contingencies 1, 2. Ecological
interactions in local assemblages may constrain the number of species that can coexist 3, 4,
but differences in diversity in similar habitats within different regions (diversity anomalies)
suggest that this limit is not firm. Variation in rate of species production could influence
regional and perhaps local diversity independently of the ecological capacity of an area to …