Species-area relationship and richness persistence as a proxy of environmental carrying capacity: a case study in a neotropical show cave

Abstract

Community stability and carrying capacity are essential core concepts in ecology because they reflect the interactions between organisms and their environment and provide clues to predictability. Since caves are considered stable habitats, we used long-term invertebrate monitoring to understand temporal and spatial carrying capacity in a neotropical cave based on species richness and beta diversity. Invertebrates were monitored from the entrance to the inner parts of the cave in plots (25m long each) in five sampling events over 10 years. Overall, 181 species were recorded. Although the turnover in species composition was considered high, the number of species remained almost constant along time, obviously considering the species oscillations between dry and rainy periods. The partitioning of beta diversity showed that in the rainy period and in the inner regions, the species replacement (turnover) was responsible for the differences in species composition over time. The richness stability and the turnover along time seem to indicate a maximum number of species that may coexist in the cave (∼64 species), probably a proxy of environmental carrying capacity. Then, despite the environmental stability of the caves, the permanent absence of light and scarcity of food resources makes these habitats restrictive to colonization, printing an intense temporal turnover in faunal composition, although with constant richness. Hence, at least for the studied cave, it seems that there is a maximum number of species it can shelter, regardless of which taxa.