From forest to pasture: an evaluation of the influence of environment and biogeography on the structure of beetle (Scarabaeinae) assemblages along three altitudinal gradients in the Neotropical region

Abstract

The objective of this study is to evaluate the effect of environmental (associated with the expansion of cattle ranching) and biogeographical factors on the diversity of dung beetle (Scarabaeinae) assemblages along three altitudinal gradients in the Neotropical region. One gradient is located in the Mexican Transition Zone, on the Cofre de Perote mountain, the other two are in the northern Andes (the Chiles Volcano and the Río Cusiana Basin). For the three gradients, the number of species decreased as altitude increased. On the Cofre de Perote, regardless of altitude, the number of species and of individuals was similar in both forest and pasture, while species composition was different between habitats. On this mountain, species turnover in pastures was characterized by the addition of new species as altitude increased. In the northern Andes, species diversity was always greater in the forest than in the pasture, and species turnover between habitats was notably influenced by species loss with increasing altitude. As such the pasture fauna of the northern Andes was an impoverished derivative of the fauna present in the forests at the same altitude characterized by species of Neotropical affinity with a limited capacity for colonizing open, sunnier habitats. The opposite occurs in the areas used by cattle on the Cofre de Perote. This habitat has its own fauna, which is mainly comprised of Holarctic and Afrotropical species adapted to the prevailing environmental conditions of areas lacking arboreal vegetation. These results suggest that the impact on beetle communities caused by human activities can differ depending on the geographic position of each mountain and, particularly, the biogeographical history of the species assemblage that lives there.A decrease in species richness and changes in the composition of the flora and fauna with increasing altitude have frequently been described in the literature (Huston 1994). However, it is not possible to describe a general relationship between changes in diversity and increasing altitude (Rahbek 1995), because the ecological factors (current environmental conditions, e.g. land use) and biogeographical factors differ in their relative effect depending on the mountain system being studied (Brown 2001). This is emphasized by the fact that we still do not understand how these factors vary and interact as altitude changes. For this reason comparative studies using the same taxonomic group along altitudinal gradients on different mountains (such as this one), and those that use several taxonomic groups along the same altitudinal gradient of the same mountain are very useful for explaining this co-variation (Lomolino 2001).Studying the altitudinal variation in dung beetle assemblages on different mountains around the world, Lobo and Halffter (2000) proposed two different biological and interrelated processes to explain the conformation of the biota on mountains, the patterns of species richness and variations in composition: horizontal colonization by elements originating fro...

Movement and population size of two dung beetle species in an Andean agricultural landscape dominated by sun-grown coffee

“…3b, d). This species seems to avoid entering large forest remnants (Escobar 2004;Escobar et al 2007), but we found that the forest patches in the landscape studied do not appear to be an effective barrier to the movement of O. conspicillatum, owing perhaps to their elongated shape and small area (\30 ha). These results highlight the need for future studies that quantify how the area, shape and position of forest patches in a landscape affect the movement patterns of the Scarabaeinae species to develop strategies for the preservation of their populations.…”

Elevational Gradient in Species Richness Pattern of Epigaeic Beetles and Underlying Mechanisms at East Slope of Balang Mountain in Southwestern China

“…As Sanders & Rahbek (2012) summarized [8], a number of factors have been proposed to explain elevational distributions of species richness patterns, and some of the most frequently tested included climate, area, geometric constraints, productivity, species pool, disturbance, habitat heterogeneity and evolutionary history [1], [17], [18], [19], [24], [47]. In our study, we tested two alternative groups of explanatory factors (environment vs. direct biotic interactions), and found strong explanatory power of environment factors.…”

“…However, most hypotheses or knowledge on species richness and diversity along elevational gradients are based on plants and vertebrates (particularly for mammals and birds) [9], [10], [11]. As the global majority of terrestrial organisms, just a few studies on insects have been examined richness patterns along elevational gradients, focusing on specific taxa such as ants [18], [19], butterflies [20], moths [21], [22], and dung beetles [23], [24], and knowledge of elevational richness patterns and underlying causes for most insects are still very poor.…”

Dung beetle assemblages in forests and pastures of El Salvador: a functional comparison

“…The lower diversity of dung beetles in Neotropical pastures compared to adjacent forests has been well documented (Klein 1989;Estrada et al 1998;Horgan 2007;Escobar et al 2007;Nichols et al 2007); however, few studies have assessed the functional consequences of species loss in derived ecosystems. Klein (1989) documented a large decline in beetle diversity in clearcuts compared to intact and fragmented forest in Amazonia.…”