Body size inequality of carabids along an urbanisation gradient

Abstract

Summary Analysis of size inequality can shed light on coexistence mechanisms and help to interpret patterns in assemblages. We tested several measures for their power to evaluate changes in carabid body size along an urbanisation gradient (city park–suburban area–rural), representing decreasing intensities of human disturbance. Carabids were collected by pitfall traps over two full activity periods in lowland oak forest patches in and near the city of Debrecen, Eastern Hungary. The average value of skewness was largest in the urban areas compared to the suburban and rural ones, indicating that small individuals were more prominent in the urban areas. The Gini coefficient also decreased from urban towards rural areas, suggesting that inequality in body size of the carabid assemblages decreased along the gradient. However, neither of these trends was significant. The Lorenz asymmetry coefficient was significantly higher in rural areas compared to suburban and urban areas indicating that there was a significant difference in inequality and/or asymmetry of body size across the gradient. This difference was primarily due to more individuals with larger body size in rural area. We suggest that the observed variation in carabid body size along the gradient is related to habitat alteration caused by urbanisation.