Local‐scale abiotic factors influence the organization of rock pool arthropod communities in a biodiversity hotspot

Abstract

AbstractDetermining drivers of community assembly is central to ecology, and patchily distributed temporary habitats offer an ideal system to study the roles of ecological and evolutionary processes in structuring communities over different spatial scales. We studied functionally diverse arthropod communities in 32 freshwater rock pools on 3 plateaus in the Western Ghats biodiversity hotspot, sampling them throughout their hydroperiod (2–7 months). Using the Hierarchical Modeling of Species Communities approach, we assessed (a) the influence of local (water chemistry, habitat complexity at the pool level) and regional (seasonality in temperature and precipitation at the plateau level) scale abiotic covariates in shaping species' occurrence, (b) the influence of species traits (dispersal/reproductive mode, body size, feeding guild) and phylogenetic relationships on species response to abiotic covariates, and (c) the strength of biotic filtering in the communities. Environmental filtering was the dominant driver of community structure, where the pool‐level covariates (mainly hydroperiod and water chemistry), explained greater variation (56.3%) in species occurrences rather than plateau‐level covariates, that is, climatic seasonality (33.7%). Spatial factors explained only 11% of the variation in species occurrences. The selected traits explained 22% variation in species' responses, with body size responding to the abiotic covariates at both spatial scales. Closely related taxa exhibited shared responses to the abiotic covariates. Only a few residual associations were observed, all among passive dispersers, indicating a low contribution of biotic filtering to community structure. Our results highlight the importance of habitat‐level factors and the key role of evolutionary processes in shaping diversity in this vulnerable landscape characterized by its seasonality.