Land use changes affect ant assemblages, resource preference, and ecosystem functions in neotropical biomes

Abstract

Land-use changes are the primary cause of biodiversity loss in terrestrial tropical environments. In these regions, such changes drastically alter vegetation structure and composition, affecting the microclimate and the availability of food resources. Despite numerous studies assessing the impacts of land-use changes, there is still a need for syntheses, reviews, and a broader approach that goes beyond taxonomic ecology (e.g., species richness), including effects on resource preference and ecosystem functions. These aspects are directly linked to ecosystem functioning and can help guide conservation strategies. In this PhD thesis, I aimed to evaluate how land-use changes and microclimatic variations affect ant assemblages, specifically species richness, nutrient preference, and insect predation. Additionally, I conducted a systematic review with a meta-analysis on the effects of land use on ant assemblages in Brazil. I found that in the Atlantic Forest biome, ants show a greater preference for amino acids and higher predation on insects. Furthermore, although predatory ants have a diet primarily based on proteins and amino acids, they increase their preference for energetic resources due to nutritional limitations in carbohydrates and lipids. I also found that the microclimate affects the nutritional preference in ants, where an increase in temperature tends to reduce the preference for amino acid-rich resources compared to carbohydrates and lipids. Furthermore, I found that land-use changes affect ant assemblages both directly and indirectly. The reduction in insect predation caused by land-use changes is mediated by the loss of ant species richness, particularly predatory species. Finally, in my review and meta-analysis, I demonstrated that highly contrasting land-use changes (e.g., from forest to pasture conversion) reduce species richness and alter the composition of ant assemblages, likely due to the loss of sensitive and specialist species. Thus, I conclude that land-use changes can cause negative effects on various aspects of terrestrial communities, such as species richness, composition, and ecosystem functions, particularly in more extreme habitat conversions. Therefore, I suggest that, whenever possible, anthropized habitats should be maintained as close as possible to their original environment to promote species conservation and ecosystem functions.