Cohabitation and niche overlap in the occupation of twigs by arthropods in the leaf litter of Brazilian Atlantic Forest

In tropical forests, twigs are the nesting resources most frequently occupied by ants in the leaf litter. During occupation, this resource may be shared among different arthropods, such as ants or non-ant arthropods, but the mechanisms that promote cohabitation in this context are poorly known. In this study, we examined if twig structure influences species cohabitation. Additionally, we calculated co-occurrence and niche overlap metrics for ant species and non-ant arthropods occupying the same twigs in the leaf litter. We collected 52 species of ants and 82 morphospecies of non-ant arthropods inside 575 twigs from fragments of Brazilian Atlantic Forest. Thirty-six ant species cohabited with non-ant arthropods, which were primarily Isopoda and Coleoptera. We observed that the twigs most commonly shared by ants and non-ant arthropods were wider, longer, and had a larger number of holes. We also found that cohabiting ants and non-ant arthropods had higher co-occurrence and niche overlap scores. We suggest that twig diameter is an important factor determining occupation by ants and other arthropods. When the twig is occupied by more than one ant species, our results show that niche overlap and cohabitation with non-ant arthropods are less common. We conclude that examining twig structure is important to better understand arthropod species cohabitation in leaf litter twigs and to study coexistence in ant assemblages that use twigs.