Formigas, biodiversidade e gradiente latitudinal: investigando interações com plantas, variação funcional e diversidade genética no Cerrado

Author(s)

Marianne Azevedo Silva

• Document type: Doctoral Thesis
• Press: Campinas, SP.
• Institution: Universidade Estadual de Campinas (UNICAMP). Instituto de Biologia
• Defense date: 2023-11-24

Examining board members

Paulo Sergio Moreira Carvalho de Oliveira; Gustavo Quevedo Romero; Vera Nisaka Solferini; Alexander Vicente Christianini; Gabriela Procópio Camacho

• Advisor: Paulo Sérgio Moreira Carvalho de Oliveira

Abstract

Biodiversity is a central concept in science and can be investigated from various viewpoints and levels of organization. One of the most consistent patterns of biodiversity distribution on the planet is the latitudinal gradient of diversity (LGD), which states that biological diversity increases from the poles towards the equator. Some groups may exhibit inverse patterns relative to the LGD, such as ants in the Brazilian Cerrado savanna. In the Cerrado, ants are highly diverse and dominant on foliage, where they can find nesting sites and nutritious sugary food resources, mainly from extrafloral nectaries (EFNs) and honeydew-producing insects. Recently, it has been reported that ant species diversity follows an inverse LGD in the Cerrado, increasing with latitude. However, other levels of biological organization along this gradient have not been explored yet. Here, we investigate ant biodiversity at different biological scales along a latitudinal gradient in the Cerrado. Additionally, we aimed to understand the factors that potentially shape these levels of diversity. In Chapter 1, we assessed how biotic and abiotic factors – latitude, environmental heterogeneity, resources, and plant and ant communities – influence the frequency of ant-plant interactions in Cerrado vegetation. Based on structured equation modelling, we found that the proportion of plants with ants in the Cerrado is indirectly and negatively related to latitude. Environmental heterogeneity and plant community also had a negative effect on ant-plant interactions. On the other hand, sugary resources from EFNs and hemipteran trophobionts, along with the ant community, positively affected the interactions. In Chapter 2, we examined the functional variation of a dominant ant, Camponotus crassus, along the latitudinal gradient of Cerrado. We characterized the mesosoma pilosity and body size of workers and evaluated their relationships with environmental heterogeneity, resources, and plant and ant communities. We also assessed possible correlations between morphological and genetic variation among sampling sites. Our results suggest that the availability of sugary liquid resources had the most significant effect on C. crassus pilosity, but not on body size. Additionally, C. crassus pilosity did not covary with genetic variation, implying potential phenotypic plasticity in this species. In Chapter 3, we assessed the genetic diversity (GD) of C. crassus along the latitudinal gradient of Cerrado and the potential factors influencing this diversity, including the ant community, environmental heterogeneity, resource availability, and C. crassus demography. We found that C. crassus GD exhibits an inverse LGD, being higher at higher latitudes. We also found that precipitation and resource availability are negatively and positively associated with C. crassus GD, respectively. The results of this thesis represent a step further in our understanding of context-dependent ant-plant interactions, intraspecific functional variation, and genetic diversity of ants in the Cerrado. Our study adds to the knowledge of LGD and the factors shaping biodiversity in the neotropical Cerrado savanna (AU)

• FAPESP's process: 17/18291-2 - Biodiversity and molecular ecology of ants (Hymenoptera: Formicidae) along a latitudinal gradient in the Cerrado
• Grantee: Marianne Azevedo Silva
• Support Opportunities: Scholarships in Brazil - Doctorate