Urbanisation and habitat loss favour thermophilic and monogynous ant species

  1. Basile Finand
  2. Thibaud Monnin
  3. Céline Bocquet
  4. Angélique Bultelle
  5. Pierre Fédérici
  6. Léa Darmedru
  7. Solène Gouffault
  8. Joséphine Ledamoisel
  9. Nicolas Loeuille

Reviewed by

Read the full article See related articles

Discuss this preprint

Start a discussion What are Sciety discussions?

Listed in

Log in to save this article

Abstract

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.

Article activity feed

  1. Version published to 10.24072/pcjournal.775
  2. Peer Community in Ecology

    Although cities are primarily designed for humans, urbanisation has generated unique sets of environmental conditions in which a broad range of species find suitable habitats. The dynamics and peculiarities of the urban biota have been the subject of investigation of urban ecologists for a few decades now. They have documented substantial variations in the diversity, composition, and functional ecology of species' communities, within cities, among cities and between urban habitats and their rural counterparts. However, these findings have often lacked mechanistic explanations rooted in theory (Lokatis et al., 2023). As such, recent theoretical progress and the current availability of life-history traits' databases could be leveraged to further decipher species responses to the multiple environmental gradients characterizing urban areas. In this context, Finand et al. (2026) aimed to understand how ecological processes unfold to shape communities of species and their traits, taking advantage of the ideal experimental ground offered by urban areas. Based on the metacommunity theory framework, they investigated the response of litter ant communities to variations in habitat distribution and environmental conditions resulting from urbanisation. 

    Urbanisation is a temporal process whereby large extents of habitats and agricultural areas have been progressively converted into urban fabrics. This has led to substantial habitat loss over time, but some patches of semi-natural habitat are still present in between buildings and urban infrastructures. These habitats are mostly found as urban parks and are either remnant patches or the product of urban greening policies. Consequently, cities are not devoid of trees, but the latter form patches that are usually much smaller and more isolated than forest patches located in the outskirts of cities. Beyond the size and isolation contrasts, urban parks are commonly affected by the urban heat island effect, by management practices generating different micro-habitats, and exposed to a wide range of anthropogenic disturbances (Chiron et al., 2024). To understand the consequences of this complex combination of conditions, Finand et al. (2026) have carried out their study in the Greater Paris, where the urbanisation process has started long-ago. They have sampled litter ants in 25 wooded urban parks of varying sizes within the city and 24 sites located within large forests of the rural surroundings of Paris. This sampling design allowed them to analyse species richness variations between urban parks and forests, but also within each type of habitat. They particularly investigated the effect of habitat amount and isolation at these two scales, and also looked for the overall effect of urbanisation on community composition and ant life-history traits.

    To provide mechanistic explanations for the observed patterns, they formulated their predictions in the light of metacommunity theory. By reconciling several non-mutually exclusive ecological theories (niche-based, coexistence-based, or neutral theories), this theoretical framework has clarified the way in which community assembly results from the combined action of environmental filters, biotic interactions, and dispersal movements (Leibold et al., 2004; Thompson et al., 2020). Even though this heuristic framework is relatively recent in urban ecology (e.g., Liere et al. (2025) and Sexton & Egerer (2026)), it holds much promise. Despite their peculiarity, urban ecosystems are governed by the same processes as any other ecosystem. One has simply to account for the fact that urban environments mediate the nature and intensities of each process, which is what Finand et al. (2026) did. 

    Accordingly, the authors associated the diversity patterns they expected to observe with varying intensities of biotic interactions, environmental filtering, and dispersal; with a particular focus on the two latter processes given the influence of habitat distribution and urban environments on them. Taking inspiration from the paradigmatic biodiversity patterns proposed by early formulations of the theory (Leibold et al., 2004), they proposed to interpret their observations in terms of optimal species sorting, mass effects, and patch- or neutral-dynamics. Using ant trait databases, they looked for additional clues reflecting the action of the hypothesized processes in variations of colony mass, social structure and species thermophily levels. 

    The diversity and distribution of more than 36,000 individuals from 29 species provided answers to their questions. Despite similar numbers of species in urban parks and forests overall (20 and 23, respectively), individual urban parks hosted more species in average. Yet, urban and forest communities of litter ants were very different, as indicated by a strong species turnover between these habitats. While habitat amount did not seem to be a limiting factor of forest ant diversity, the amount of habitat available around urban parks positively influenced their species richness. Finally, the authors reported differences in life-history traits, urban ants being more thermophilic and more often monogynous than forest ants. 

    In line with their approach, the authors interpreted these results through the lens of metacommunity theory. Together, their findings indicate that dispersal is not strong enough to homogenise community composition at the regional scale. The important contrasts observed between forests and urban parks and among parks, combined with low to intermediate dispersal levels, set conditions in which species sorting generates important turnover among communities. Within each habitat type, the picture is however more complex. Mass effects due to frequent dispersal might be the reason behind the high similarity of ant communities in forests, but dispersal could be more limited among urban parks. In this context, the long-distance dispersal of winged queens, typical of monogynous species, could give them an advantage in urban parks. In contrast, the fact that urban ant species are more thermophilic than their forest relatives (as previously observed by Menke et al., 2011; see also Piano et al., 2017) could reflect either a filtering effect of the urban heat island, or that urban parks have more open and diverse habitats. Note that if micro-habitat heterogeneity were indeed higher in urban parks, under optimal species sorting, this would explain their higher species richness, and why it scales positively with park size. The authors carefully discuss these results and their alternative explanations.

    Importantly, Finand et al. (2026) explain that their study does not directly address the effects of habitat loss and fragmentation per se on urban biodiversity, since they do not have data before and after urbanisation, and perform most analyses at the patch level (Riva et al., 2024). Similarly, they do not explicitly test for the currently debated urban biotic homogenisation phenomenon (Sexton & Egerer, 2026). Nonetheless, their results could inform future predictions about these effects and their theoretical approach should be more broadly applied in future studies about these questions. This comprehensive framework necessarily makes interpretations more complex, forcing ecologists to jointly consider (i) environmental filtering and the underlying habitat heterogeneity, (ii) species dispersal across isolation gradients, and (iii) potential local interactions in habitats of different sizes. However, this seems to be the best way to build further knowledge in urban ecology. The authors embraced this complex task and managed to provide answers to their initial questions, while opening future research avenues. I would thus strongly recommend the study by Finand et al. (2026), which is a very welcome integration of theoretical insights from metacommunity theory into urban ecology. 

    References

    Chiron, F., Lorrillière, R., Bessa-Gomes, C., Tryjanowski, P., Casanelles-Abella, J., Laanisto, L., Leal, A., Van Mensel, A., Moretti, M., Muyshondt, B., Niinemets, Ü., Ortí, M. A., Pinho, P., Samson, R., & Deguines, N. (2024). How do urban green space designs shape avian communities? Testing the area–heterogeneity trade-off. Landscape and Urban Planning, 242, 104954. https://doi.org/10.1016/j.landurbplan.2023.104954 

    Basile Finand, Thibaud Monnin, Céline Bocquet, Angélique Bultelle, Pierre Fédérici, Léa Darmedru, Solène Gouffault, Joséphine Ledamoisel, Nicolas Loeuille (2026) Urbanisation and habitat loss favour thermophilic and monogynous ant species. bioRxiv, ver.4 peer-reviewed and recommended by PCI Ecology https://doi.org/10.1101/2025.02.25.640022 

    Leibold, M. A., Holyoak, M., Mouquet, N., Amarasekare, P., Chase, J. M., Hoopes, M. F., Holt, R. D., Shurin, J. B., Law, R., Tilman, D., Loreau, M., & Gonzalez, A. (2004). The metacommunity concept: A framework for multi-scale community ecology. Ecology Letters, 7(7), 601–613. https://doi.org/10.1111/j.1461-0248.2004.00608.x 

    Liere, H., Bichier, P., Gonzales, E., Lin, B. B., Jha, S., Lucatero, A., & Philpott, S. M. (2025). Metacommunities in community gardens: Relative strength of environmental, spatial, and social filters for species assembly in highly managed urban patches. Landscape Ecology, 40(11), 209. https://doi.org/10.1007/s10980-025-02237-3 

    Lokatis, S., Jeschke, J. M., Bernard-Verdier, M., Buchholz, S., Grossart, H.-P., Havemann, F., Hölker, F., Itescu, Y., Kowarik, I., Kramer-Schadt, S., Mietchen, D., Musseau, C. L., Planillo, A., Schittko, C., Straka, T. M., & Heger, T. (2023). Hypotheses in urban ecology: Building a common knowledge base. Biological Reviews, 98(5), 1530–1547. https://doi.org/10.1111/brv.12964 

    Menke, S. B., Guénard, B., Sexton, J. O., Weiser, M. D., Dunn, R. R., & Silverman, J. (2011). Urban areas may serve as habitat and corridors for dry-adapted, heat tolerant species; an example from ants. Urban Ecosystems, 14(2), 135–163. https://doi.org/10.1007/s11252-010-0150-7 

    Piano, E., De Wolf, K., Bona, F., Bonte, D., Bowler, D. E., Isaia, M., Lens, L., Merckx, T., Mertens, D., van Kerckvoorde, M., De Meester, L., & Hendrickx, F. (2017). Urbanization drives community shifts towards thermophilic and dispersive species at local and landscape scales. Global Change Biology, 23(7), 2554‑2564. https://doi.org/10.1111/gcb.13606 

    Riva, F., Koper, N., & Fahrig, L. (2024). Overcoming confusion and stigma in habitat fragmentation research. Biological Reviews, 99(4), 1411–1424. https://doi.org/10.1111/brv.13073 

    Sexton, A. N., & Egerer, M. (2026). Re-Thinking the Urban Biotic Homogenization Hypothesis. Ecology Letters, 29(2), e70342. https://doi.org/10.1111/ele.70342 

    Thompson, P. L., Guzman, L. M., De Meester, L., Horváth, Z., Ptacnik, R., Vanschoenwinkel, B., Viana, D. S., & Chase, J. M. (2020). A process-based metacommunity framework linking local and regional scale community ecology. Ecology Letters, 23(9), 1314–1329. https://doi.org/10.1111/ele.13568

  3. Version published to 10.1101/2025.02.25.640022 on bioRxiv