Diversity Patterns of Dung Beetles along a Mediterranean Elevational Gradient
Department of Life, Health and Environmental Sciences, University of L’Aquila, Via Vetoio, 67100 L’Aquila, Italy
cE3c-Centre for Ecology, Evolution and Environmental Changes, Azorean Biodiversity Group, Faculdade de Ciências e Engenharia do Ambiente, Universidade dos Açores, rua Capitão João D’Avila, 9700-042 Angra do Heroísmo, Portugal
Author to whom correspondence should be addressed.
Academic Editors: Roberto Pizzolotto and Mauro Gobbi
Received: 30 July 2021
Revised: 23 August 2021
Accepted: 28 August 2021
Published: 31 August 2021
Mountains are ideal natural laboratories to study how biodiversity is influenced by environmental characteristics because climate varies rapidly from lowlands to high elevations. Scientists have investigated how the number of species varies with elevation for the most disparate plant and animal groups worldwide. However, species richness is only one aspect of biodiversity that does not consider species abundances. The so-called Hill numbers are a unified family of mathematical indices that express biodiversity in terms of both richness and abundance. We used Hill numbers to investigate how dung beetle diversity varies along an elevational gradient in a Mediterranean mountain. We found that scarabaeids were the most abundant dung beetle group. These insects construct subterranean nests protecting their offspring from desiccation during warm and dry summer climatic conditions. Additionally, in accordance with their preference for open habitats, we found that dung beetles are more abundant and diversified in grasslands than in woodlands. In the woodlands, diversity increased with elevation because of tree thinning, whereas in the grasslands, diversity decreased because of increasingly harsher environmental conditions. This indicates a trade-off in the beetle response to elevation between the positive effects of increasing the availability of suitable habitats and the worsening of environmental conditions.