Does Urbanization Drive Evolution in White Clover?

Authors

Victor Alfonso, DePauw University
Seika Shiba, DePauw University
Yangjie Tan, DePauw University
Philips Akinwole, DePauw UniversityFollow

Files

Document Type

Poster

Publication Date

Fall 10-2-2019

Abstract

Urban areas are functioning ecosystems with profound effects on the ecology and evolution of organisms. Systematic investigations of species interactions in urban versus rural environments can improve our understanding of the mechanisms through which urbanization drives natural selection on populations. To facilitate our understanding of the selective factors driving adaptation in cities, we examined adaptive phenotypic changes by quantifying the relative frequency of cyanogenesis (hydrogen cyanide production after tissue damage) in 180 white clover (Trifolium repens) populations along urbanization gradients in six Midwest (USA) cities. White clover, a perennial plant is naturally polymorphic for cyanogenesis; a chemical defense against herbivores. We found that the frequency of cyanogenic plants within populations decreased towards the urban centers in three of six cities, but no consistent pattern in genetic diversity in three cities. The population density strongly predicted the average cyanogenic frequencies across Midwest cities. Our study supports the notion that insect herbivory is higher in rural environments, hence, higher frequency of cyanogenesis in rural area indicated a defense mechanism against herbivores. Nonetheless, our findings partly illustrate the complex nature of urbanization effects on plant‐herbivore interactions which requires accounting for direct or indirect mechanisms involving other biotic or abiotic factors. We suggest that plant populations are adapting to urbanization gradients, but more studies are needed to assess whether the capacity of this species to adapt to urban ecosystems is a general phenomenon.

Funding and Acknowledgements

Funding: Science Research Fellows Program, the Kranbuehl Roberts Hillger Endowed Fund, the Faculty Summer Research Fund, and the Faculty Development Program

Recommended Citation

Alfonso, Victor, Seika Shiba, Yangjie Tan, Philips Akinwole. Does Urbanization Drive Evolution in White Clover?" Poster presented at the DePauw University Science Research Fellows Poster Session, Greencastle, IN, October 2019.