Human activities have drastically altered earth’s ecosystems. Chief among these changes is the alteration of habitats and the conversion of forests, pastures, and rangeland into homes, schools and commercial and industrial sites. The ecological consequences of land-use change associated with housing development (hereafter urbanization) could alter plant interactions with pollinators and floral antagonists, and thereby affect natural selection on native plant traits. We estimated nectar robbing and florivory in Gelsemium sempervirens from pairs of suburban and forested sites in Raleigh, NC across 2 years, and estimated pollen deposition on stigmas.

Results/Conclusions

Plants received almost twice as much florivory and nectar robbing in suburban vs. forested sites. Plants also received nearly 25% more Gelsemium pollen per day in suburban vs. forested sites, but this effect was not statistically significant. However, plants in suburban sites received over 5 times more heterospecific pollen per day than in forested sites, potentially from the greater number of flowering garden species. These results suggest that urbanization may select for more highly defended and less attractive flowers, due to increased floral antagonism and possibly greater pollen deposition. Thus, urbanization has the potential to change natural selection on plant traits by altering interactions with floral antagonists and pollinators.