Forest Cover and Geographic Distance Shape Ant Assemblages in the Southwestern Brazilian Amazon.

Understanding the drivers affecting species richness and composition in local communities is crucial for discerning differences among communities in a specific region. In large regions, a variety of environmental conditions shape diversity, reflecting the peculiarities of each location, such as available resources and species interactions. While many species are associated with forest habitats, some can adapt to open environments, reflecting how environmental changes affect ant assemblages. The southwestern Brazilian Amazon stands out for significant contrasts in precipitation and forest cover, with the drier and deforested east compared to the wetter and forested west. Thus, we investigated how precipitation, forest cover and spatial distance influence ant species richness and composition. We conducted the study by selecting 16 sampling areas. We collected 365 species, of which 151 were classified based on their habitat use. We observed that increased forest cover is directly related to increased ant species richness, especially for forest specialists, highlighting the sensitivity of these species to forest habitat loss or gain. Additionally, we found that spatial distance between communities plays a significant role in explaining variance in ant species composition, surpassing the influence of forest cover. However, species composition is still influenced by variability in forest cover and precipitation, even when controlling for geographical distance. Our results provide important insights into ant diversity and composition in the Amazon. We emphasize the importance of considering the different responses of ants to environmental factors, using habitat-use guilds, to guide effective biodiversity conservation measures.