Date Thesis Awarded


Access Type

Honors Thesis -- Open Access

Degree Name

Bachelors of Science (BS)




Joshua Puzey

Committee Members

Leah Shaw

Lizabeth Allison


Global climate change can drive many changes in species interactions. One primary way it affects species is by changing climates, causing species to expand their ranges and allowing them to interact with species from whom they were previously isolated. In plants, new species interactions can result in hybridization – the creation of hybrid offspring between two separate species. This hybridization can increase gene flow between the species and lead to introgression, the transfer of genetic material from one species to another through hybrid backcrossing with the parent species. My thesis investigates hybridization in the model system Asclepias (milkweed) by analyzing phenotypic and genetic data from historical and present populations of milkweed. Our analysis of several sympatric populations of common milkweed (A. syriaca) and poke milkweed (A. exaltata) in Virginia reveals extensive genetic admixture despite phenotypic segregation. We also found evidence of introgression from common milkweed into the poke milkweed genome, supporting our hypothesis that through hybridization with common milkweed, poke milkweed is rapidly adapting to the changing habitat on the eastern United States and moving out of the forest. By investigating the mechanisms of hybridization and introgression in milkweed, researchers can better understand the impact climate change has on species and whether introgression is a viable way species can avoid extinction.

Creative Commons License

Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.