Date of Award

2020

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Oberle, Brad

Area of Concentration

Biology

Abstract

Plants and their pollinators present a particularly concerning case for potential mismatch due to potentially differing phenological responses. To test whether seasonal warming might affect subtropical flowering phenology and whether such effects might impact pollinator visitation, I conducted an experiment in which representatives of four different flowering plant species were either passively warmed in open-top chambers or left unwarmed in interspersed control plots. Over a period of seven weeks, phenological observations were collected in the form of bud, bloom, and seed counts while pollinator visitation was monitored. I hypothesized 1) that all species would significantly advance in response to the warming treatment, 2) that treatment plots would receive lower pollinator visitation, and 3) that treatment plots would also display lower levels of pollinator biodiversity. Two out of four species responded significantly to the warming treatment: ​Asclepias tuberosa (Apocynaceae)​, ​ which experienced a significant delay,​ ​ and ​Stachytarpheta jamaicensis ​ (Lamiaceae)​, which experienced a significant advancement compared to control. Although treatment was a significant factor in phenological discrepancy overall, species identity proved to be more influential. In addition, pollinator visitation and diversity were significantly lower in treatment plots, although this effect may be an artifact of the chambers themselves. These results support the idea that future shifts in flowering phenology in response to climate warming are likely in subtropical regions as well as at higher latitudes. Judging by the fact that species identity was a stronger factor in determining phenological response, phenological responses are also likely to differ by taxonomic group, potentially resulting in plant-pollinator mismatch.

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