Urbanisation and habitat loss favour thermophilic and monogynous ant species

Environmental changes such as urbanisation and related habitat loss and fragmentation profoundly impact ecological communities by altering habitats, resources, and microclimates. Yet, the impacts of the resulting environmental conditions on metacommunity dynamics, ranging from species sorting to mass effects, remain a subject of debate. Ants, with diverse life histories and strong ecological effects, are ideal model species to study these pressures. We investigated the response of ant communities, including taxonomic and functional diversity, to urbanisation and habitat fragmentation in the Paris region, comparing wooded areas in 25 urban parks vs. 24 rural forests outside the city. We found a clear difference in species composition between urban and rural environments, with a higher prevalence of thermophilic species and a tendency for monogyny in the city. Forest communities were homogeneous across the size levels we studied, while park communities differed noticeably depending on park size, with larger parks harbouring more species. Our findings suggest that urbanisation selects specific ant traits and favours more thermophilic species, thereby increasing the mean thermal preference of urban communities. These selective effects influence which species can colonise and survive in different patches, shaping metacommunity structure and potentially affecting the resilience of ant communities under climate change.