Environmental drivers of species composition and functional diversity of dung beetles along the Atlantic Forest–Pampa transition zone

Abstract

Human activities are causing a rapid loss of biodiversity, which impairs ecosystem functions and services. Therefore, understanding which processes shape how biodiversity is distributed along spatial and environmental gradients is a first step to guide conservation and management efforts. We aimed to determine the relative explanatory importance of biogeographic, environmental, landscape and spatial variables on assemblage dissimilarities and functional diversity of dung beetles along the Atlantic Forest-Pampa (i.e. forest-grassland) transition zone located in Southeast South America. We described each site according to their biogeographic position, environmental conditions, landscape features and spatial patterns. The compositional dissimilarity was partitioned into turnover and nestedness components of b-diversity. Mantel tests and generalised dissimilarity models were used to relate b-diversity and its components to biogeographic, environmental, landscape and spatial variables. Variation partitioning analysis was used to estimate the pure and shared variation in species composition and functional diversity explained by the four categories of predictors. Biome domain was the main factor causing dung beetle compositional dissimilarity, with a high species replacement between Atlantic Forest and Pampa. Biogeographic, environmental, landscape and spatial distances also affected the patterns of dung beetle dissimilarity and b-diversity components. The shared effects of the four sets of predictors explained most of the variation in dung beetle composition. A similar response pattern was found for dung beetle functional diversity, which excluded biogeographic effects. Only the pure effects of environmental and spatial predictors were significant for species composition and functional diversity. Our results indicate that dung beetle species composition and functional diversity are jointly driven by environmental, landscape and spatial predictors with higher pure environmental and spatial effects. The forest-grassland transition zone promotes a strong species and trait replacement highly influenced both by environmental filtering and dispersal limitation. Land cover configurationThe land cover conditions around sites (1 km radii circular sectors) were obtained from high-resolution satellite images

Response of dung beetle taxonomic and functional diversity to livestock grazing in an arid ecosystem

“…In this context, the objective of this study was to compare the taxonomic and functional response of dung beetles to livestock under two different environmental management regimes in the Dry Chaco: open pastures and silvopastoral systems with native tree canopy. Whereas studies performed in humid forests showed a marked decrease in taxonomic and functional diversity of dung beetles in livestock areas (Audino et al, 2014;Gómez-Cifuentes et al, 2017;da Silva & Cassenote, 2019;Guerra Alonso et al, 2019), based on the few studies performed in dry forests, we did not expect a marked influence in the Dry Chaco. Moreover, we expected that cattle systems preserving native canopy will support higher taxonomic and functional richness and greater similarity in dung beetles community composition to native forest than open pastures.…”

“…In contrast to taxonomic diversity, the response of dung beetle functional diversity to disturbance has been less explored. However, recent studies show similar patterns of functional diversity reduction following forest replacement by cattle pastures (Gómez-Cifuentes et al, 2017;da da Silva & Cassenote, 2019).…”

“…Most of the dung beetle studies in forest ecosystems were conducted in humid forests e. g. (Gómez-Cifuentes et al, 2017;da da Silva & Cassenote, 2019;Guerra Alonso et al, 2019). However, little is known about their response in dry forests (Barragán et al, 2014;Guerra Alonso et al, 2020).…”

Livestock grazing impact differently on the functional diversity of dung beetles depending on the regional context in subtropical forests

“…Seasonality and the total amount of precipitation were the major differences among regions in this study. Consistent with this pattern, Nichols et al 55 , proposed that the functional response of dung beetles to anthropogenic disturbance depends on the regional context whereas da Silva and Cassenote 53 proposed that climatic seasonality is the main determinant of functional dung beetles response. Environmental dissimilarity between native habitats and land uses has already been identified as one of the main predictors of changes in biological assemblages at both local and regional scales 20 , 58 .…”

“…While previous studies explored either local or regional functional responses of dung beetles to environmental gradients or human disturbances 29 , 30 , 53 – 55 ; this is the first study that simultaneously explore both components through the comparison of similar land uses among different regions. Consistent with previous studies, the replacement of native forest by open pastures strongly reduced functional diversity in humid forest and showed low impact on dry forests 27 , 29 , 56 .…”