Fine-scale habitat selection in tree-dwelling spiders: an experimental approach

Habitat selection by spiders is strongly influenced by biotic factors such as the availability and diversity of prey and abiotic factors such as temperature, humidity, and the structural complexity of the habitat. Structural complexity is an aspect that intensely affects species persistence, population stability, and the coexistence of interacting species. Trees comprise a complex set of microhabitats due to their large biomass and heterogeneity of the architectural components of their trunk surface and branches. Spider species that live on trunks have diversified physiological or morphological adaptations that confer advantages in this environment. In this study, we experimentally examined the habitat choice by the tree-dwelling spiders Selenops cocheleti (Selenopidae), Corinna rubripes (Corinnidae), and Loxosceles gaucho (Sicariidae). We found that microhabitat specialization was restricted to trunk architectural characteristics rather than plant taxonomy. Selenops cocheleti and C. rubripes significantly preferred loose barks and holes in the trunks, respectively, showing that both spider species can evaluate the physical structure of the microhabitat on a fine scale. On the other hand, L. gaucho selected crevices and holes near the base of the trunk without giving much importance to the physical characteristics of the microhabitat per se (e.g., depth, height, length). Our findings indicate that for generalist predators like spiders, coexistence relies heavily on spatial segregation driven by distinct habitat preferences, irrespective of their method for capturing prey.