Graduation Year


Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts


Environmental Analysis

Reader 1

Dr. Matthew Austin

Reader 2

Dr. Diane Thomson

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Terms of Use for work posted in Scholarship@Claremont.


Previous studies have demonstrated the influence of climate change, competition, and co-flowering on flowering phenologies. Non-native plants may see changes to one or more of these variables when they are moved from a native to non-native area. Therefore, we hypothesize that a plant's ability to undergo a phenological shift from one area to another may be positively correlated to its ability to act as a successful invader. Viola odorata, commonly known as sweet violet, is a species native to Europe and Asia that has become invasive in the U.S. and Australia following its naturalization. To investigate the potential overlap between flowering phenology, invasion biology, and global climate change in this study, we used data on European and U.S. populations of V. odorata from the Global Biodiversity Information Facility (GBIF) database to look at whether (1) invasive populations of V. odorata have different flowering times than their native counterparts, (2) if invasive populations will respond to long-term changes in temperature and precipitation differently than native populations, and (3) whether V. odorata experienced different degrees of flowering synchrony with other members of the Viola genus in its native or invasive range around the time of its first introduction. We found that, on average, U.S. populations of V. odorata flower 16 days later than European populations, but that temperature, precipitation, and year were not statistically significant explanations for why this shift occurred. However, we do find that V. odorata overlaps in flowering time with other Viola species to a greater extent in the Northeastern U.S., which suggests that greater flowering synchrony in the Northeastern U.S. is consistent with the hypothesis that flowering synchrony may have facilitated the invasion success of V. odorata in this region. This opens the door for further research regarding the abiotic and biotic drivers of this shift in V. odorata phenology and shows the potential importance of flowering phenology as part of the explanation for invasion success in plant species.

This thesis is restricted to the Claremont Colleges current faculty, students, and staff.