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Thesis Abstract – Lester (2005)


The Impact of Edge Mediated Effects on Bee-Pollinated Salvia mellifera (Lamiaceae)

Author and college:

Adrienne Lester, Pomona College




Bachelor of Arts in Biology




Habitat fragmentation often leads to edge-mediated effects on many native plant communities. Coastal sage scrub is one plant community that experiences detrimental edge effects such as lowered pollinator visitation. Specific species, such as Salvia mellifera are impacted because of their dependence on bee-facilitated pollination. This study examines how edge effects impact the relationship between plant distribution and bee-facilitated pollination in S. mellifera. Here, it is hypothesized that as population sizes of S. mellifera decrease due to habitat fragmentation, bee visitation rates decrease along the edge of a fragment as compared to the interior. This leads to reduced fitness of the edge populations versus interior populations. This hypothesis is tested by censusing S. mellifera and monitoring pollination visitation to individuals found along the edge and within the interior. To compare the relative fitness of those individuals, the ratio of flowers to fruit and also seed to ovule ratios will be used. Also, fruit set and seed output per volume of glomerole will be utilized. It is expected that a lower abundance of pollinators will be found along the edge of each patch versus the interior. This difference in visitation is expected to lead to decreased fitness of individuals along the edge as compared to the interior. As a result, edge individuals will have a lowered fruit set and seed output per volume of glomerole as compared to interior individuals. This study is proposed to explore bee-facilitated pollination as mediators of gene flow, an underrepresented subject in the research of edge mediated effects. The consequence of lowered pollinator abundance and visitation has far reaching implications for S. mellifera and many other bee-pollinated species, including lack of genetic variation, decreased fitness, and contraction of range.

For more information:

Contact Gail Sundberg – gail.sundberg@pomona.edu

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