Cooperative Fish and Wildlife Research Units Program: North Carolina
Education, Research and Technical Assistance for Managing Our Natural Resources

Ruzi, S.A., E. Youngsteadt, A. Cherveny, J. Kettenbach, H. K. Levenson, D.S. Carley, J.A. Collazo, and R.E. Irwin. 2023. Bee species richness through time in an urbanizing landscape of the southeastern USA. Global Change Biology (Accepted).


Compared to non-urban environments, cities host ecological communities with altered taxonomic diversity and functional trait composition. However, we know much less about how these urban changes take shape over time. Using historical bee (Apoidea: Anthophila) museum specimens supplemented with online repositories and researcher collections, we investigated whether bee species richness tracked urban and human population growth over the past 118 years. We also determined which species were no longer collected, and whether those species shared certain traits. Additionally, we looked at collector behavior over time. We focused on Wake County, North Carolina, US where human population size has increased over 16 times along with the urban area within its largest city, Raleigh, which has increased over four times. We estimated bee species richness with occupancy models, and rarefaction and extrapolation curves to account for imperfect detection and sample coverage. To determine if bee traits correlated with when species were collected, we compiled information on native status, nesting habits, diet breadth, and sociality. We used non-metric multidimensional scaling to determine if collectors contributed different bee assemblages over time. In total, there were 328 species collected in Wake County. We found that while bee species richness varied there was no clear trend in bee species richness over time. However, recent collections (since 2003) were missing 195 species and there was a shift in trait composition over time, particularly an increase in above-ground nesters. The top collectors in the dataset differed in how often they collected bee species, but this was not consistent between historic and contemporary time periods as some contemporary collectors grouped closer than others together potentially due to focusing on urban habitats. Use of historic collections and complimentary analyses can fill knowledge gaps to help understand temporal patterns of species richness for taxonomic groups that may not have long-term data.