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DEFENSE TRADE-OFFS IN THE EVOLUTION OF THE FRUITS AND FLOWERS OF GENUS CORNUS
Title
DEFENSE TRADE-OFFS IN THE EVOLUTION OF THE FRUITS AND FLOWERS OF GENUS CORNUS.
Creator
De La Pascua, Danielle R, Mason, Chase, University of Central Florida
Abstract / Description
The optimal defense hypothesis predicts that the allocation of plant defenses across plant organs is proportional to the importance of a given organ to plant fitness. Despite this, much less work has been devoted to the study of reproductive defenses in plants relative to vegetative structures like leaves. This study examines the apparancy hypothesis and the resource availability hypothesis using a phylogenetic comparative approach within the genus Cornus. During the 2016 growing season,...
Show moreThe optimal defense hypothesis predicts that the allocation of plant defenses across plant organs is proportional to the importance of a given organ to plant fitness. Despite this, much less work has been devoted to the study of reproductive defenses in plants relative to vegetative structures like leaves. This study examines the apparancy hypothesis and the resource availability hypothesis using a phylogenetic comparative approach within the genus Cornus. During the 2016 growing season, plants of 25 species of Cornus were tracked for flower and fruit phenology as well as sampled for floral and fruit tissue in a common garden experiment at the Arnold Arboretum of Harvard University. This tissue was used to quantify floral and fruit defensive chemistry (e.g. tannin activity, total phenolics, total flavonoids, titratable acidity), and fruit palatability traits (e.g. water, sugar, lipid, and protein content), and the color of reproductive structure using reflectance spectroscopy. Native habitat environmental data was obtained using digitized herbarium records and publicly available environmental data layers. Trait-trait and trait-environment relationships were assessed with phylogenetic generalized least squares regression. The evolution of later flowering phenology was correlated with increased floral phenolics and tannins, and the evolution of increased fruiting duration was correlated with increased fruit tannins, both supporting the apparancy hypothesis. Additionally, the evolution of higher fruit sugar content was correlated with higher fruit tannins, and a strong evolutionary trade-off between the production of tannins and the production of flavonoids was observed. With respect to habitat, floral and fruit flavonoids and tannins were consistently lower in species native to warmer environments, while fruit phenolics and was higher in drier environments, which may support the resource availability hypothesis.
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Date Issued
2019
Identifier
CFH2000508, ucf:45674
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFH2000508
UNDERSTANDING PLANT COMMUNITY COMPOSITION IN AGRICULTURAL WETLANDS: CONTEXT DEPENDENT EFFECTS AND PLANT INTERACTIONS
Title
UNDERSTANDING PLANT COMMUNITY COMPOSITION IN AGRICULTURAL WETLANDS: CONTEXT DEPENDENT EFFECTS AND PLANT INTERACTIONS.
Creator
Boughton, Elizabeth, Quintana-Ascencio, Pedro, University of Central Florida
Abstract / Description
Community composition results from an integrated combination of random processes, regional habitat spatial structure, local environmental conditions, and species interactions. For example, the outcome of plant interactions can change depending on local environmental conditions such as nutrient availability, land management, or herbivory intensity. In particular, plant interactions may vary between facilitation and competition depending on ecological context, with facilitation expected to be...
Show moreCommunity composition results from an integrated combination of random processes, regional habitat spatial structure, local environmental conditions, and species interactions. For example, the outcome of plant interactions can change depending on local environmental conditions such as nutrient availability, land management, or herbivory intensity. In particular, plant interactions may vary between facilitation and competition depending on ecological context, with facilitation expected to be prevalent under stressful conditions. I present the results of four studies that address different aspects of the community assemblage and dynamics emphasizing the synergistic effect of different processes. In the first, I investigated the importance of habitat isolation in determining species richness of wetlands with contrasting land use. The second describes an experiment to test the hypothesis that plant interactions with an unpalatable plant (Juncus effusus) would range from competition in ungrazed areas to facilitation in grazed areas and predicted that facilitative effects of Juncus would differ among functional groups of beneficiary species and be strongest when grazing was intense. In the third, I examine the community composition impacts of Juncus and predicted that Juncus would preserve functional diversity in grazed wetlands but that the effects of Juncus would vary along a grazing gradient. The fourth study investigated the relative importance of competition and nutrients in determining wetland invasion in two different land use types. Broadly, I demonstrate that the importance of different processes (habitat isolation, nutrient availability, competition/facilitation) to community composition is dependent on ecological conditions. This integrated view of community dynamics is interesting from a purely ecological perspective but also can be applied to understanding ecological problems such as exotic invasions and restoration of disturbed habitats. 
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Date Issued
2009
Identifier
CFE0002678, ucf:48234
Format
Document (PDF)
PURL
http://purl.flvc.org/ucf/fd/CFE0002678