Urbanisation impacts the diversity, coloration, and body size of wild bees in a Mediterranean city

Arnaud Badiane (1, 2) , Lise Ropars (3, 4) , Floriane Flacher (1) , Lucie Schurr (1, 5) , Marie Zakardjian (1) , Laurence Affre (1) , Magali Deschamps-Cottin (1, 6) , Sophie Gachet (1) , Christine Robles (1) , Benoît Geslin (1, 7)

1 IMBE - Institut méditerranéen de biodiversité et d'écologie marine et continentale
2 IGFL - Institut de Génomique Fonctionnelle de Lyon
3 ThéMA - Théoriser et modéliser pour aménager (UMR 6049)
4 CESCO - Centre d'Ecologie et des Sciences de la COnservation
5 iEES Paris - Institut d'écologie et des sciences de l'environnement de Paris
6 LPED - Laboratoire Population-Environnement-Développement
7 ECOBIO - Ecosystèmes, biodiversité, évolution [Rennes]

Urbanisation is a growing phenomenon causing the decline of wild bees globally. However, bees manage to persist in the urban environment thanks to islands of vegetation in public parks and private gardens. While we are beginning to comprehend the impact of urbanisation on bees’ diversity and abundance, our understanding of its impact on the functional diversity of wild bees is limited. Here, we employ an integrative approach to investigate the response of wild bees to urbanisation at the community, species, and individual levels. To do so, we sampled wild bees in 24 public parks along an urbanisation gradient in the Mediterranean city of Marseille. We found that species richness and abundance decreased in more urbanised areas, but increased in larger city parks. Moreover, we observed larger individuals within species, but not larger species, in larger city parks, suggesting that park size plays a crucial role for urban bees at the intraspecific level. Interestingly, brightly coloured species were found in parks surrounded by a large amount of impervious surface, highlighting the importance of colour traits in the response to environmental changes. Finally, we showed that larger species, but not larger individuals, were also more colourful. In summary, our study not only confirmed that urbanisation negatively impacts community-level traits, but that it also filters species based on coloration and affects individuals’ body size. This improves our understanding of the functional response of wild bees to urbanisation. We suggest that increasing park size may partly compensate for the negative effects of urbanisation on wild bees.

Mots clés: Urban ecology; Conservation; Coloration; Mediterranean; City; Parks

Domaines: Biodiversité et Ecologie; Zoologie des invertébrés

Arnaud Badiane, Lise Ropars, Floriane Flacher, Lucie Schurr, Marie Zakardjian, et al.. Urbanisation impacts the diversity, coloration, and body size of wild bees in a Mediterranean city. Regional Environmental Change, 2024, 24 (2), pp.41. ⟨10.1007/s10113-024-02199-3⟩. ⟨hal-04564145⟩