Date of Award

Spring 2026

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

Biological Sciences

Program/Concentration

Ecological Sciences

Committee Director

Lisa E. Wallace

Committee Member

Erik Yando

Committee Member

Jessamyn Manson

Abstract

Natural plant hybridization, or the cross between genetically distinct lineages, can act as a driver of biodiversity through the production of genetic variation and phenotypic novelty. While its evolutionary significance is well documented, hybridization has been insufficiently examined from an ecological perspective. Thus, it is not well understood how hybridization outcomes may influence and be influenced by ecological factors, including abiotic conditions and biotic interactions.

This dissertation offers a multi-disciplinary examination of a novel natural mosaic hybrid zone involving highbush blueberries (Vaccinium; Ericaceae) distributed across a heterogeneous landscape. Highbush blueberries were selected for their ecological importance and propensity to hybridize in the wild. Objectives of this dissertation were to: 1) examine the patterns and breadth of hybrid trait variation, 2) determine how genetic and phenotypic variation is structured across populations and factors driving population phenotypic structure, and 3) characterize the ecological impacts of a hybridizing population on pollinator behavior.

Across the Coastal Plain and Piedmont of Virginia, nine sample sites with coexisting populations of the hybrid, Vaccinium × marianum, and its parent species, Vaccinium fuscatum and Vaccinium formosum, were thoroughly examined. Traits related to leaves, plant architecture, and berries were collected for two years, revealing that V. × marianum exhibits phenotypic novelty iii compared to both parents. Population genetic analyses indicated significant structure within each species, but population phenotypic structure was stronger and differed in intensity between years for the parent species. Genetic and abiotic distances were significant predictors of inter-population phenotypic distances in the parent species, while abiotic distances alone were significant for V. × marianum. The Vaccinium taxa overlap in flowering timing and share a pollinator network; small bees were the dominant visitor and other insects, like flies and butterflies, exhibited floral size preferences. Unlike the parent species, V. × marianum exhibited significant interannual variation in both visitation frequency and visitor diversity. This work demonstrates morphological, genetic, and environmental novelty in V. × marianum, which distinguishes it from its parent species and suggests that it may be an evolutionarily significant and long-lasting lineage. Collectively, this dissertation showcases the importance of incorporating ecological practices and theory into plant hybridization research.

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DOI

https://doi.org/10.25777/7vat-3v75

ISBN

9798197810397

ORCID

0000-0003-3337-8766

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Available for download on Saturday, June 26, 2027

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