Microhabitat selection and niche overlap: Drivers of spider coexistence in a tropical limestone cave

Stable temperature, humidity, and oligotrophy may be essential in microhabitat selection, shaping niche overlap and species coexistence within cave ecosystems. To explore this hypothesis, we assessed the distribution and microhabitat preferences of four non-obligate cave-dwelling spiders: Loxosceles anomala, Scytodes itapevi, Philoponella vittata, and the exotic Oecobius navus. Using 1-m² quadrats, we surveyed spider distribution and abundance in a limestone cave, considering environmental conditions and prey availability during wet and dry periods. Significant differences were observed between moist and dry periods regarding light intensity, wind speed, air temperature and moisture, potential prey, and the abundance of L. anomala. The exotic spider O. navus was more specialist, preferred brighter habitats, and showed lower niche overlap. Conversely, the three native species displayed greater niche overlap and preferred darker and more humid environments. Spatial disparities, rather than temporal variation, in species distribution underscored the influence of cave habitat conditions on species segregation. Furthermore, our findings highlighted the limited ability of the non-native O. navus to occupy more illuminated cave areas, thereby potentially safeguarding these habitats against biological invasion by this species.