Sex-specific interaction of body condition and asymmetry in carabids in distinct urbanisation stages

Abstract

Physiological condition of an animal is flexible and can quickly change in relation to the quality of its environment. This makes it potentially suitable as an estimator of environmental stress. We studied the condition in three predatory ground beetles, Carabus nemoralis, Nebria brevicollis and Pterostichus melanarius along an urbanisation gradient (forest-suburban area - forest fragments in urban park) in Sorø, Denmark to test whether urbanisation-related stress is reflected in body condition. We also considered the interaction between condition and the true asymmetry using a local polynomial regression model. Females showed consistently better condition than males in all studied species. The condition indices in C. nemoralis and N. brevicollis were higher in the urban habitats than the other sites, while P. melanarius showed better condition in the suburban forest fragments than the forest or urban habitats. A significant negative correlation was found between condition and asymmetry for C. nemoralis and N. brevicollis in the suburban as well as urban forest fragments. This indicates a complex interaction between tolerance limits, feeding conditions and stress levels during advancing urbanisation, emphasising the importance of using multiple criteria for assessing its impact on biodiversity.