Effects of food resources on arboreal ant communities in brazilian savanna

• Ano de defesa: 2017
• Autor(a) principal: Ribeiro, Laila Fieto
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Universidade Federal de Viçosa
• Palavras-chave em Português: Formigas - Comunidades - Ecologia; Formigas - Cerrados - Brasil; Insetos - Alimentos; Entomologia Agrícola
• Link de acesso: https://locus.ufv.br//handle/123456789/27093

The availability and quality of food resources are among the major mechanisms structuring animal communities. One of the most important and extensively explored food resources by arboreal ants are extrafloral nectaries (EFNs), but is contest their role as mechanism structuring communities and it is unclear how EFNs can affect the local diversity. Furthermore, arboreal ants tend to have high nutritional imbalanced in their diet due to feeding extensively on carbohydrate-rich resources and short supply of proteinaceous food. Therefore, the community response to the nutritional composition of food resources available in the environment might be important to predict patterns in diversity and abundance. This thesis aim to investigate the influence of food resources on arboreal ant community structure in Brazilian savanna, ecosystem that has an exceptional arboreal ant diversity and very high incidence of EFN-bearing trees. In the first chapter, we explored the effects of extrafloral nectaries on arboreal ant diversity at multiple scales, focusing on how patterns observed on individual trees influence ant communities at the site level. Arboreal ants were sampled in 32 plots, where the proportion of EFN-bearing trees ranged from 0 - 60%. We demonstrated that EFNs-bearing trees have a marked effect on communities of arboreal ants at the site scale, influencing species richness and composition, independently of overall tree density and richness. We also showed that the proportion of EFNs-bearing trees at site scale have a positive effect on overall ant species richness primarily through higher occurrence of non-core ant species in the ant-EFN network. In the second chapter, we performed a manipulative field experiment, supplementing trees with protein and CHO-rich resources. In this study, we investigated the variation in nutrient attractiveness among stoichiometrically contrasting arboreal ant species, and its implications for ant community structure. Considering the overall community, we demonstrated that arboreal ants were more attracted to supplements rich in protein, the scarcest nutrient on arboreal environment. However, we observed different responses in abundance, richness and composition of ant species between protein and CHO supplements, according to their discrepancies in N-limitation. Lastly, we also showed a change in abundance of foraging ants after trees supplementation, but the responses to different nutrients were also dependent on stoichiometric discrepancies among species. In summary, we demonstrated that EFN-bearing trees represent an important mechanism to the structure of local arboreal ant community; and due to stoichiometric differences among ant species within the assembly, balances of carbohydrate and protein available in resources might generate patterns in distribution and composition of species in arboreal ant communities.