Life Sciences Commons^™

Reproductive Ecology And Phenology Of Thalassia Testudinum (Hydrocharitaceae) In Tampa Bay, Florida, Sheila Scolaro

USF Tampa Graduate Theses and Dissertations

Successful sexual reproduction and recolonization are critical in maintaining genetic diversity within seagrass meadows. Thalassia testudinum flower, fruit and seedling production were assessed visually at 10 sites within Tampa Bay, Florida approximately every 4 weeks from May to July 2017 to determine if there is spatial and temporal variation in sexual reproductive effort and if location within a meadow effects sexual reproductive effort. Results from this study reveal strong temporal variability throughout the reproductive season. The month of May was observed as peak Thalassia testudinum anthesis and June was peak fruiting in Tampa Bay during 2017. Flower and fruit density …

Measuring Flowering Phenology And Its Consequences: A Systematic Review, Samantha M. Mangum

USF Tampa Graduate Theses and Dissertations

Despite growing interest in flowering phenology among ecologists, as reflected by an increase in the number of papers, there is little information on how studies typically measure and describe a plant’s flowering phenology. The focus of this study was the literature on flowering phenology and the approaches researchers have taken to quantify flowering phenology. Initially, a comprehensive description of the breath of literature on flowering phenology was produced. From there, I described the current research on flowering phenology: the year that the studies were published, the locations of the studies, and the particular biomes where the studies were performed. The …

Epigenetic Response To Challenging Environmental Conditions, Marta Robertson

USF Tampa Graduate Theses and Dissertations

The discovery of epigenetic mechanisms has ignited speculation into their role in ecological and evolutionary processes. In particular, the contribution of epigenetic variation to adaptation or phenotypic plasticity that is distinct from genetic variation would be an important addition to existing evolutionary mechanisms. Although the research of epigenetic mechanisms from an ecological and evolutionary (or eco-evolutionary) perspective has been growing, it is still unclear how epigenetic variation might function in natural populations and settings and to what extent it might serve to mediate population response to changing environmental conditions over time. Over the course of my dissertation, I explored the …

The Archaeopalynology Of Crystal River Site (8ci1), Citrus County, Florida, Kendal Jackson

USF Tampa Graduate Theses and Dissertations

The Woodland-period (ca. 1000 B.C. to A.D. 1050) fisher-hunter-gatherers of the Crystal River drainage on Florida’s Big Bend Coast are well known among southeastern archaeologists for their elaborate shell mound architecture, maritime lifeway, and exotic exchange goods. Recent archaeological investigations at the Crystal River site have employed high-resolution topographic mapping, geophysical surveys, trench excavations, and coring to model the temporality of mound construction and occupation at the site; this work has set the stage for subsequent research focusing on community structure, resource extraction, and human-ecosystem dynamics. However, like many central and north peninsular Gulf Coast sites, our understanding of Crystal …

Population Genetics And Epigenetics Of Two Salt Marsh Plant Species Along An Environmental Gradient, Christy M. Foust

USF Tampa Graduate Theses and Dissertations

Phenotypic plasticity is the ability of a given genotype to exhibit different phenotypes in response to environmental variables, which can impact population level processes. Plasticity of ecologically-relevant traits is important to an organism’s environmental response; however, the underlying mechanisms of plasticity are largely unknown. Ecological epigenetics may offer mechanisms (e.g. DNA methylation) underlying phenotypic plasticity. Epigenetics can be defined as the underlying molecular mechanisms that allow one genotype to exhibit different phenotypes. Differential DNA methylation is one epigenetic mechanism that has been correlated with a number of ecologically-relevant traits; including, differential herbivory in Viola cazorlensis, spinescence in Ilex aquifolium …

Water Availability As The Driving Factor Of Growth And Physiological Function Of Co-Occurring Scrub Species In Central Florida, Tammy Foster

USF Tampa Graduate Theses and Dissertations

Florida scrub is a xeromorphic upland shrub community dominated by evergreen oaks that resprout after fire, occurring on moderately to excessively well-drained nutrient-poor sand. Scrub is home to several threatened and endangered animal species (e.g., Florida scrub-jay, gopher tortoise, and indigo snake) and rare and endemic plants. Urban development and agriculture has greatly reduced and fragmented scrub habitat, and because of this Florida scrub is considered one of the most endangered ecosystems in the United States. Climate change is a further threat to Florida scrub. Under a warmer and drier climate, scrub species will be exposed to more frequent and …

An Investigation Of The Factors Leading To Invasion Success Of Non-Native Plants Using A System Of Native, Introduced Non-Invasive, And Invasive Eugenia Congeners In Florida, Kerry Bohl

USF Tampa Graduate Theses and Dissertations

The overwhelming majority of plant species introduced into a new range never become invasive. Consequently, identification of factors allowing the small fraction of successful invaders to naturalize, increase in abundance, and displace resident species continues to be a key area of research in invasion biology. Of the considerable number of hypotheses that have been proposed to resolve why some plant species become noxious pests, the enemy release hypothesis (ERH) is one of the most commonly cited. The ERH maintains that invasive plants succeed in a new range because they are no longer regulated by their coevolved natural enemies, and this …

Chlorophyll Fluorescence And Thermal Stress In Archaias Angulatus (Class Foraminifera), Heidi M. Toomey

USF Tampa Graduate Theses and Dissertations

ABSTRACT

Benthic foraminifers that host algal symbionts are similar to corals in that they rely on their algal endosymbionts for their energy needs, calcify prolifically, and are sensitive to changes in environmental conditions. They are abundant in the benthos of coastal coral-reef areas and are found throughout the tropical and subtropical regions. Pulse Amplitude Modulated (PAM) chlorophyll fluorometry and chlorophyll a extraction techniques were used to quantify and compare the photosynthetic responses of the benthic foraminiferal, Archaias angulatus and their isolated endosymbionts, Chlamydomonas hedleyi, to short-term changes in temperature. Maximum quantum efficiency (F_v/F_m) and rapid …

Systematics Of Harrisia (Cactaceae), Alan R. Franck

USF Tampa Graduate Theses and Dissertations

The genus Harrisia Britton (Cactaceae) comprises species of columnar cacti that are united by a unique seed morphology. The species range in form from prostrate shrubs to large trees and are native to South America and the Caribbean region. Harrisia is placed in an unresolved position within subtribe Trichocereinae of tribe Cereeae of subfamily Cactoideae. Relationships among the species within Harrisia are also poorly understood. In this study, several species of Harrisia were sequenced for as many as seven different regions of nuclear and plastid DNA. Species in the Caribbean were also examined with amplified fragment length polymorphisms. The morphology …

Heterogeneous Stress Response In A Clonal Invader (Imperata Cylindrica): Implications For Management, Sarah Grace Sanford

USF Tampa Graduate Theses and Dissertations

Life history traits such as growth, survival, and clonality can vary within a population. When such variation exists in a population of an invasive species, it can affect population dynamics, and if any part of the variation has a genetic basis the population can evolve in response to control regimes. Evolutionary responses to control efforts may shift the population towards a few more resilient genotypes, or towards different types in different microenvironments, depending on the scale of gene flow with respect to the patchiness of the environment. The purpose of this study is to examine whether the application of stress …

The Effect Of Mulching On Herbaceous Wetland Creation Areas In West-Central Florida, Christopher J. Anderson

USF Tampa Graduate Theses and Dissertations

Wetland mulching is the transfer of soil (often from a wetland area which is going to filled or otherwise impacted) on to the surface of a wetland creation area. The primary intent of mulching is to transfer wetland vegetation in the form of seeds and propagules, from the natural wetland to the creation area. This technique also is used to transfer organic matter and microbial fauna existing in the soil to the creation area. My study examines the effects that wetland mulching has on: 1) percent organic matter in the soil, 2) the wetland affinity of plant communities present, 3) …

Genetic Variation In Chrysopsis Floridana Small, The Endangered Florida Golden Aster, As Revealed By Random Amplification For Polymorphism Detection (Rapd), Laurie Lysle Walker Markham

USF Tampa Graduate Theses and Dissertations

Chrysopsis fioridana Small (Asteraceae) is a federally endangered plant endemic to the Tampa Bay area of west central Florida. It is confined to the sand pine scrub community, growing in open, sunny, and sandy areas or in disturbed areas at the edges of scrub. As a means ofassessing the genetic variability ofthis species, eight populations in Hillsborough County were compared with a seed stock collection housed at Bok Tower Gardens in Lake Wales using random amplification for polymorphism detection (RAPD). The objectives of this study were to (I) describe the overall genetic variation among and within populations and subpopulations of …

Abundance And Distribution Of Herbaceous Angiosperms In Grass-Sedge Marshes Of West-Central Florida: The Effect Of Seasonal Water-Level Fluctuation, Pamela S. Botts

USF Tampa Graduate Theses and Dissertations

Grass-sedge marshes in west-central Florida were studied to determine the abundances and distributions of herbaceous angiosperms. Cluster analysis, reciprocal averaging, and a biotic boundaries technique were used to analyze the relationship between community composition and depth within the marsh. Shallow areas were dominated by Rhynchospora filifolia, Dichanthelium sabulorum, and Rhynchospora cephalantha. Abundances of the species fluctuated seasonally and varied between marshes. Deep areas of individual marshes differed markedly from shallow areas and from each other. A deep, well-drained marsh supported a monospecific stand of Juncus repens, while a less deep, but poorly drained marsh had a …