Greater local diversity under older species pools may arise from enhanced competitive equivalence

Local ecological communities in geologically older regions tend to contain more species, a pattern normally attributed to the accumulation of species in the regional species pool over evolutionary time. In this study we used plant-fungal microcosms to test the hypothesis that older regions to have higher local richness not simply because older species pools are more speciose, but also because the constituent species have evolved traits that allow them to co-occur more readily in local communities.