Spatiotemporal responses of ant communities across a disturbance gradient: the role of behavioral traits

Abstract

This study examined how chronic anthropogenic disturbance impacts the spatiotemporal dynamics of ant foraging activity and the role played by behavioral traits. Ten plots (0.1 ha) along a gradient of chronic disturbance intensity were sampled in Catimbau National Park (Caatinga vegetation, Brazil). Vegetative structure, ground surface temperature, and ant communities in shaded and sun-exposed microhabitats were characterized during the day and at night. Each ant species’ degree of nocturnality and shaded microhabitat use were determined. Along the disturbance gradient, the frequency of sun-exposed microhabitats increased, as did the daytime ground surface temperatures; also, community composition, but not ant abundance or species richness, changed. Independent of disturbance intensity, community composition differed between day and night, and ant abundance and species richness were higher during the day. Interestingly, most species did not display strictly diurnal habits, nor did they avoid foraging in sun-exposed habitats. However, species common in more disturbed areas were more diurnal and used sun-exposed microhabitats more than species common in less disturbed areas. Many species displayed marked behavioral plasticity that was unrelated to disturbance intensity. Disturbance intensity did influence shaded microhabitat use but not the degree of nocturnality. We conclude that Caatinga ants are already morphologically, behaviorally and physiologically adapted to harsh environmental conditions; that species with different behavioral traits replace each other along the disturbance gradient; and that more plastic species can persist by shifting their microhabitat use.