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- Author or Editor: M. Bátki x
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Environmental stress can lead to a reduction in developmental homeostasis, which could be reflected in increased variability of morphological traits. Fluctuating asymmetry (FA) is one possible manifestation of such a stress, and is often taken as a proxy for individual fitness. To test the usefulness of FA in morphological traits as an indicator of environmental quality, we studied the effect of urbanisation on FA in ground beetles (Carabidae) near a Danish city. First, we performed a critical examination whether morphological character traits suggested in the literature displayed true fluctuating asymmetry in three common predatory ground beetles, Carabus nemoralis, Nebria brevicollis and Pterostichus melanarius. Eight metrical (length of the second and third antennal segments, elytral length, length of the first tarsus segment, length of the first and second tibiae, length of the proximal and distal spines on the first femurs) and one meristic (the number of spines on the second tibiae) traits were examined. Most of them showed FA but not consistently. Females generally displayed a higher level of FA than males. Finally, we examined the changes in the level of FA in bilateral morphological traits along an urbanisation gradient (forest - suburban forest - forest fragments in urban park) to test whether environmental stress created by urbanisation is reflected in FA. Ground beetles common along a Danish urbanisation gradient did not seem to indicate differences in habitat quality by their level of FA.
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.
