Multi-scale impacts of urbanization on species distribution within the genus Tetramorium

Context Urbanization is a global change which deeply impacts landscapes. Long studied through transects along urbanization gradients, ecological response to urbanization can now be investigated precisely using direct GIS-based measures. Ecological responses are strongly scale-dependent as both large- and fine-scale environments drive species distributions. Objectives To bridge the gaps regarding the effect of multiple scales on the distribution of biodiversity in the context of urbanization, the present study questions how urbanization structures the distribution of Tetramorium ants at different spatial scales. Methods Based on model averaging procedures, we investigated similar to 1400 individuals belonging to four Tetramorium species at four distinct spatial scales, from urban microhabitat (1 m around the nest) to urban landscape (500 m around the nest) in 19 urban gradients in South-eastern France. Results The probabilities of occurrences of Tetramorium caespitum and T. immigrans simultaneously depended on urbanization at the landscape and local scales, with T. caespitum avoiding urban microhabitats and impervious landscapes whereas T. immigrans favored them. These multi-scale impacts of urbanization were species-dependent as T. moravicum was associated with nonurban landscapes only, and T. semilaeve showed no association whatever the tested variables. Conclusions These results highlight the importance of considering several spatial scales simultaneously to study the impact of urbanization on species distributions. The highly contrasted responses to urbanization of T. immigrans and T. caespitum may indicate niche partitioning processes driven by urbanization. The future monitoring of the distribution range dynamics of these two species should provide insightful information into the impact of urbanized landscapes on species distribution.