Forest conversion into pasture selects dung beetle traits at different biological scales depending on species pool composition

Abstract

The conversion of forests into open areas has large effects on the diversity and structure of native communities. The intensity of these effects may vary between regions, depending on the existence of native species adapted to open habitats in the regional pool or the time since habitat change. We assess the differences in species richness and functional diversity of dung beetle communities (Coleoptera: Scarabaeinae) between native forests and novel pasturelands of the Atlantic Forest and the Cerrado, two biomes with contrasting histories of human occupation in Brazil. We conducted standardized surveys in seven forest fragments and adjacent pastures in each region and measured 14 traits in individuals collected in each type of habitat at each particular site. We calculated functional richness, functional evenness, functional divergence, and community‐weighted mean of traits for each area, and analyzed individual variation through nested variance decomposition and Trait Statistics. Communities were richer and more numerous at the Cerrado. We did not find any consistent relationship between functional diversity and forest conversion beyond the changes in species diversity. Although landscape changes were more recent at the Cerrado, the colonization of the new habitat by native species already adapted to open habitats lessens the functional loss in this biome. This indicates that habitat change's effects on trait diversity depend on the regional species pool rather than on time since land conversion. Forest conversion effects were primarily due to internal filtering. The effects of external filtering only appear at the intraspecific variance level, with contrasting differences between the Cerrado, where traits related to relocation behavior and size are selected, and the Atlantic Forest, where selection operates for traits related to relocation behavior and flight. These results evidence the importance of considering individual variance to address the responses of dung beetle communities to forest conversion.

Evidence of drastic loss of dung beetle diversity after 25 years in an introduced Brazilian pasture

“…In the tropics, introduced pastures are typically considered a limiting environment for dung beetles (Louzada & Carvalho e Silva, 2009). Pastures present divergent environmental conditions (e.g., temperature and light intensity) compared to the native vegetation (Pessôa et al, 2023). However, the dung beetle species that colonize pastures play a crucial role in ecosystem maintenance, contributing to important ecological functions such as nutrient cycling, cattle parasite control, and improvement of soil fertility (Nichols et al, 2008).…”

“…However, the negative impacts of anthropogenic environments may manifest years after their establishment (Correa et al, 2020;Escobar et al, 2008). In pastures, several factors may cause declines in the populations of some dung beetle species, thus constraining their diversity over time: (1) the presence of alien and invasive species (e.g., the African species Digitonthophagus gazella (Fabricius, 1787), which has been spreading throughout American pastures, see Mesquita-Filho et al, 2018); (2) the low-quality food source represented by bovine manure can negatively affect individual fitness (Servín-Pastor et al, 2021); (3) the use of Ivermectin, an endectocide used to control parasites in cattle, can have detrimental effects on dung beetle behaviour, diversity, and individual health (Correa et al, 2022) and ( 4) soil compaction and previous adaption of the regional fauna to open habitats may select species with specific traits (Pessôa et al, 2023). Therefore, to understand the dynamics of dung beetle assemblages in tropical pastures, there is a need for studies comparing community composition over time.…”

The impact of eucalyptus and pine plantations on the taxonomic and functional diversity of dung beetles (Coleoptera: Scarabaeidae) in the southern region of Ecuador

“…However, there is currently a progressive degradation and depletion of biological systems and their diversity owing to human activities and strategies (Soto et al 2019). In addition, it is threatened by habitat deterioration and fragmentation, as well as other causes, such as the introduction of exotic species, land use change, and climate change, which can compromise important ecosystem functions and services, as well as the structure of the landscape (Pessôa et al 2023;Maciel et al 2023). Both habitat loss and fragmentation drive a range of environmental changes that can affect the suitability of habitats for wildlife (Larsen et al 2008;Correa et al 2019;Nunes et al 2021).…”