Abundance patterns of terrestrial isopods along an urbanization gradient

The abundance of terrestrial isopods (Isopoda: Oniscidea) was evaluated along an urban-suburban-rural gradient. We tested two hypotheses regarding the response of species: (i) habitat specialist hypothesis, according to which the abundance of the forest specialists would increase, while the abundance of the urban environment specialist isopods would decrease along the urban-rural gradient, and (ii) opportunistic species hypothesis (abundance of the generalist species would increase by increasing level of urbanization). The abundance of the forest specialist isopod Trachelipus ratzeburgii increased significantly along the studied gradient. An opposite tendency was observed for the abundance of the urban environment specialist isopod Porcellio scaber , as it was significantly higher in the urban area than in the suburban and rural sites. One generalist species (Trachelipus rathkii) gained dominance in the urban area, while other two generalists (Armadillidium vulgare and Porcellium collicola) showed no significant changes in abundance along the gradient