Intraspecific variation in bumble bee size across habitat types and effects on foraging distances in an urban area

Author

• Tanusri GudavalliFollow
• Sevan SuniFollow

Date of Award

Winter 12-12-2025

Degree Type

Thesis

Degree Name

Bachelor of Science

Department

Biology

First Advisor

Sevan Suni

Second Advisor

James Sikes

Third Advisor

Naupaka Zimmerman

Abstract

Body size has important ecological consequences. For bees, body size can influence foraging distances, thermal tolerance, and the ability to pollinate specific flowering plant species. Body size has also been predicted to mediate responses to urbanization, but whether larger or smaller bees are more likely to persist is not straightforward. On the one hand, larger bees may be better able to cross areas of impervious surface to reach parks and gardens with food or nesting resources. On the other hand, smaller bees need fewer resources and may be less likely to experience resource limitation in small parks or gardens. Drivers of body size include both genetic and environmental factors. Here, we examined intraspecific variation in body size for workers of the bumble bee Bombus vosnesenskii within gardens, parks, and small strips of living vegetation in San Francisco, California. We measured the intertegular distance of male and female bees, and assessed if these measures were associated with the area of natural habitat in which they were caught. We also used a population genomics approach to explore if body size predicts the distances that bees travel. Females were larger than males, and body size was not associated with the size of the natural areas in which bees were caught. Our analysis of movement patterns suggests that larger bees travel farther than smaller bees. This supports the notion that larger bees may be better able to cross areas of inhospitable habitat in urban areas to obtain floral resources, which may facilitate gene flow in both bee and plant populations.

Recommended Citation

Gudavalli, Tanusri and Suni, Sevan, "Intraspecific variation in bumble bee size across habitat types and effects on foraging distances in an urban area" (2025). Biology Student Research. 3.
https://repository.usfca.edu/biol_stu/3