Dung beetles (Coleoptera: Scarabaeinae): trends and gaps in knowledge, species associations and fire impacts in tropical savannas

Abstract

Patterns of co-occurrence are crucial for understanding community structure and species coexistence, as well as predicting the effects of disturbances on ecosystem functioning. Scarab beetles (Coleoptera: Scarabaeinae) are excellent organisms for testing ecological hypotheses and mechanisms of coexistence in tropical ecosystems. The coexistence of scarab beetles may be mediated by factors such as habitat structure, niche diversity, available resources, and biotic interactions. In tropical forests, the coexistence of various scarab beetle species is favored by the high diversity of niches and available resources. In tropical savannas, frequent disturbances (e.g., fire) and microclimatic variations may limit coexistence. Despite advances in understanding scarab beetle co-occurrence patterns in tropical ecosystems, the understanding of the effects of disturbances such as fire in the Cerrado is still limited. Given the resistance and resilience of scarab beetles to fire in the Cerrado and their crucial role in this ecosystem, understanding the mechanisms that promote the coexistence of these species and post-fire recovery of these communities may be crucial for the development of management and conservation strategies. This thesis seeks to broaden our understanding of the ecology and processes shaping scarab beetle communities in tropical ecosystems, with a focus on savannas. The thesis is divided into three parts: The first part addresses the global context of scarab beetle ecology in tropical savannas. In this chapter, we conduct a systematic review of the literature on "scarab beetles in tropical savannas." This review allows us to identify key trends and gaps in knowledge on the subject, providing insights and directions for future research. The second part of the thesis examines, in a regional context, the factors determining the coexistence of scarab beetle species in tropical ecosystems. In this second chapter, we test the influence of factors such as habitat type, food resources, and sampling time on species co-occurrence patterns in a mosaic of ecosystems, including savannas. We find that habitat and food resources explain the coexistence of scarab beetle species, with the community dynamics primarily shaped by stochastic processes. These results help us understand the dynamics of these communities in tropical environments and emphasize the importance of conserving a mosaic of landscapes composed of both forests and savannas, as these environments shape scarab beetle diversity. The third part covers, in a local context, the response of scarab beetle communities to fire in savanna environments. In this third chapter, we investigate the post-fire response of scarab beetle communities in open Cerrado areas. We find that fire had minimal impact on the community and species co-occurrence. We also observe that both stochastic and deterministic processes shape the community. These results contribute to a better understanding of ecological processes involved in the recovery of burned landscapes in the Cerrado, providing insights for the development of management and conservation strategies in this environment.