Spatial Overlap and Behavioral Interactions Among Four Habronattus Jumping Spider Species in a Mixed-Species...

Within mixed-species assemblages, closely related species may face interspecific competition and reproductive interference. Species may evolve adaptations to outcompete or coexist, though most assemblages likely exist in a nonequilibrium state between the two extremes. Understanding the dynamics between potentially syntopic species requires careful studies conducted at a fine spatial resolution, an especially important consideration for small invertebrate animals. We characterized interspecific interactions within a mixed-species assemblage consisting of four species of Habronattus jumping spiders, a genus that can be found in syntopic assemblages where males are known to indiscriminately court conspecific and heterospecific females alike. Through detailed focal observations, we evaluated how species overlap in their spatial occurrence, temporal occurrence, light environment, movement level, and behavioral interactions, including courtship. We assessed whether the observed heterospecific interactions occurred more frequently than random chance by comparing the observed data to network reference models. Our findings revealed interspecific overlaps across all evaluated variables, which may indicate shared environmental requirements amongst the species and potential interspecific competition and interference. However, there was a notable temporal shift between H. calcaratus and H. coecatus. H. decorus showed some divergence in spatial occurrence and light environment that may be a phylogenetic signal or potentially associated with its distinct courtship display. Additionally, we observed sex differences in movement levels across all species that could represent a selection for male "scramble competition" strategy. Lastly, heterospecific behavioral interactions, including courtship, were frequently observed but occurred less often than random chance, as represented by network reference models. Altogether, our findings suggest that individuals in this assemblage are engaged in some level of interspecific competition and reproductive interference, but there may be mechanisms to mitigate these pressures. This study establishes an ecological foundation to investigate possible adaptive responses in this assemblage, such as reproductive character displacement and sensory drive.