Urbanisation and habitat fragmentation favour thermophilic and monogynous ant species

Environmental changes such as urbanisation and habitat fragmentation profoundly impact ecological communities by altering habitats, resources, and microclimate. Ants, with diverse life histories and strong ecological effects, are ideal models 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 24 urban parks vs 25 rural forests outside the city. We found a clear difference in species composition between urban and rural environments, with a higher prevalence of monogynous and thermophilic species in the city. Forest communities are homogeneous across the three fragmentation levels we studied, while park communities differ 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.