Abiotic niche partitioning among congeneric species in an Atlantic forest fragment

Understanding the processes that allow phylogenetically related plant species coexist is important to understand the ecological and evolutionary processes that structure biological communities. In this study, we investigated how the species Erythroxylum simonis, Erythroxylum pauferrense and Erythroxylum citrifolium share ecological niche dimensions according to the abiotic characteristics of their environments of occurrence. To this end, in ten pre-established plots in an Atlantic Forest remnant in northeastern Brazil, we carried out a population survey of the three species and characterised their abiotic niche by measuring light availability, humidity and the physical–chemical properties of the soil. We used generalised linear models to test whether abiotic variables influence species abundance. Our results indicate that the three species coexist along the different environmental gradients, with some level of niche overlap. The species E. simonis is the best competitor, showing generalist behaviour and the highest abundance in all environmental gradients. We emphasise that the adult populations of the species have adapted to various environmental and ecological challenges. Thus, the results reported are influenced by their ability to perform well in terms of physiology, growth and survival in their early-life stages.