Ant habitat-use guilds response to forest-pasture shifting in southwestern Amazon

Abstract

Abstract Ant assemblages have been used as bioindicators of the response of biodiversity to different types of anthropogenic disturbances. However, usual diversity metrics (e.g., ant species richness and composition) sometimes seem fair limited to show a general panorama of human impacts. Thus, we verified habitat-use ant guilds as a complementary predictable parameter, based on the ant fauna reported to thirteen forest fragments and pastures in southwestern Brazilian Amazon. Specifically, we hypothesized that forest specialist, open-habitat specialist, and generalist ants would present distinct responses to forest-pasture shifting. We expected that the forest-pasture shifting promotes a decrease in the species richness of forest specialists and an increase in open-habitat specialists, while the generalists would have few changes in their richness because they can live in both habitats. As expected, the species richness of forest specialist ants decreased, and open-habitat ants increased with forest-pasture shifting, while generalists had few changes. This indicates that in human-induced open habitats (e.g., pastures) are essentially made up by generalist ants and open-habitat ant specialists that replace forest specialists. Additionally, considering the plasticity of generalist ants, they can be considered as primary elements of ant assemblages. Therefore, a future step is to quantify the limit of forest cover clearing in human-induced land uses that assure a higher species richness of forest-specialist ants than other habitat-use guilds.