Habitat and food resource type, rather than sampling date, drive co-occurrence of dung beetle species in a tropical ecosystem mosaic

Abstract

The species’ coexistence and distribution patterns are fundamental in community ecology research. Niche partitioning is used to evaluate co-occurrence patterns resulting from species interactions. Dung beetle communities are ideal models for understanding ecological patterns and processes. However, their co-occurrence patterns remain poorly understood. We tested if habitat type, sampling date, and food resources could explain the co-occurrence patterns of dung beetles. We expected that habitat would have the most impact on species co-occurrence, followed by food resource and sampling date. We conducted our study during the rainy season of 2012, using baited pitfall traps in a mosaic of four habitats including montane semideciduous forest, cerrado, rupestrian field, and introduced pasture, resulting in 16 sites. We used the Cooccur R package to analyze species co-occurrence probabilities and tested the effects of niche partitioning on species co-occurrence via DistLM analysis. We collected 2.743 individuals, representing 86 dung beetle species. In most co-occurring pairs, species exhibited random associations. Our results supported the hypothesis that habitat and food resources explained dung beetle co-occurrence. Habitat explains 13% of the total variance in co-occurrence patterns, food resources (7%), and sampling date (6%). Overall, our model explained 31% of the variance correspond to the sum of each variable isolated with the values shared between them. Our results suggested that dung beetle species' co-occurrence was stochastic. I.e., non-biotic external factors can also potentially explain the coexistence of species with similar requirements. Food resources were important in co-occurrence. This is consistent with the lottery competition since colonization by species on ephemeral resources is random and by chance. Niche partitioning had little explanatory power for co-occurrence patterns, however, tropical forests have the potential to maintain many positive species associations. Here, the sampling date did not influence the species' co-occurrence, possibly due to stable temperatures and consistent precipitation during the season.