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Contribution Of Lianas To Plant Area Index And Canopy Structure In A Panamanian Forest, Maria Elizabeth Rodriguez-Ronderos

Theses and Dissertations

Lianas are an important component of tropical forests, where they reduce tree growth, fecundity and survival. Competition for light among plants may be intense; however the amount of light that lianas intercept is poorly understood. We used a large-scale liana removal experiment to quantify light interception by lianas in a Panamanian secondary forest. We measured the change in plant area index (PAI) and forest structure six weeks after cutting lianas in eight 80x80 m plots and in eight control plots, and then annually for four years. We used ground-based LiDAR to measure the 3-dimensional canopy structure before cutting lianas and …

Assessing The Importance Of Nurse Plant Associations To The Growth Of Pre-~Reproductive Yucca Brevifolia, Eric James Chameroy

UNLV Theses, Dissertations, Professional Papers, and Capstones

Facilitation and competition among plant species, in addition to abiotic factors, play an important role in determining plant community structure in arid and semi-arid environments. I conducted a study in Dry Lake Valley, Lincoln County, Nevada, USA to investigate the importance of nurse plant associations to pre-reproductive Yucca brevifolia (Joshua tree). Dry Lake Valley lies within a transition desert between the Mojave and Great Basin Deserts with ecotonal plant communities consisting of species representative of both deserts. A vegetation survey described the communities in which this study was conducted as a Y. brevifolia woodland dominated by an understory of Ephedra …

Assessing The Impacts Of Macroalgal Competition And Parrotfish Grazing On Coral Cover In The Middle Florida Keys, Kylie Smith

All Theses

The coral reefs of the Florida Keys National Marine Sanctuary (FKNMS) are diverse ecosystems that support thousands of marine organisms. Unfortunately, the live coral cover on these reefs has dramatically decreased over the last 30 years even in the most protected areas of the sanctuary. Environmental changes have contributed to this decline in coral cover by creating optimal conditions for macroalgal growth. These macroalgae species are fast growing and out-compete slow growing corals for space and nutrients. Herbivores known to forage on macroalgae, including long-spined sea urchins and parrotfishes, have decreased in abundance. A synthesis of data from across the …

Perch Selection By Male Dragonflies (Odonata, Anisoptera) Related To Competitive Ability And Species Composition, Jessica L. Beard

Biological Sciences Theses & Dissertations

Males of many species of dragonflies (Odonata, Anisoptera) establish territories in aquatic habitats where they compete with other males for access to food and females. Territorial males typically perch on emergent vegetation and chase rival males who intrude into their territories. This dissertation research examined the role of male size in perch height selection, position on the perch, and competitive ability. Four hypotheses were tested: 1) Dragonfly species would vary by size and that territorial species would show sexual size dimorphism (SSD), 2) Perch height selection would be related to dragonfly size, 3) Position on the perch would be related …

Monochamus Titillator Oviposition And Intraspecific Competition In Shortleaf Pine Bolts, Ryan Patrick Rastok

Graduate Theses and Dissertations

Monochamus titillator (Coleoptera: Cerambycidae) feed on trees in the family Pinaceae as adults and larvae. Adults feed on healthy twigs and branches and oviposit on stressed, dead, or dying trees. Prior to oviposition, females construct pits on the bark surface using their mandibles. The number of eggs laid beneath bark, where oviposition pits have been constructed, varies greatly. Developmental time and adult body size also vary greatly. I investigated oviposition and intraspecific competition with the goal of determining the degree to which various insect densities and oviposition times impact the following: 1) oviposition pit construction; 2) egg deposition; 3) emergence, …

Phylogenetically Novel Species Are More Successful Due To High Competitive Ability At Local And Regional Scales, Amy C. Patterson

Senior Honors Papers / Undergraduate Theses

While few introduced exotic species become invasive, this small number of species poses serious threats to biodiversity, ecosystem function, and recreation, leading ecologists to study why certain species become invasive and why certain communities are prone to invasions. Several leading hypotheses seek to explain invasiveness, including the Enemy Release Hypothesis, the trait superiority hypothesis, and the Biotic Resistance Hypothesis, but none are consistently supported in the literature. We suggest that the lack of uniting hypothesis is a result of the inability to put multiple proposed mechanisms in the same framework, and suggest for a uniting framework Darwin’s Naturalization Hypothesis along …

Round Goby-Induced Changes In Young-Of-Year Yellow Perch Diet And Habitat Selection, Christopher John Houghton

Theses and Dissertations

A critical step in the recruitment of age-0 yellow perch (Perca flavescens) to the

adult population occurs during their transition to the demersal stage. If larval age-0

yellow perch survive recruitment bottlenecks imposed by alewife (Alosa

pseudoharengus) and dreissenid mussels, they transition to demersal feeding in late

August and early September. In Lake Michigan, demersal age-0 yellow perch seek

rock substrate where they begin feeding on benthic invertebrates in late summer.

That research preceded the invasion of the round goby (Neogobius melanostomus), a

species that can have negative impacts on benthic forage. The current study used

the spread of round …

An Investigation Of The Effects Of Increased Tidal Inundation, Competition, And Facilitation On Salt Marsh Systems, Jennifer A. Hyder

USF Tampa Graduate Theses and Dissertations

The low-lying topographic nature of salt marshes makes plants in these communities particularly vulnerable to increased salinity and inundation exposure associated with sea level rise. Both increased salinity and inundation have been cited as major causes of reduced plant performance and survival in marsh and areas fringing marsh. In addition to limitations imposed by physical stress, interspecific interactions have also been shown to mediate the performance and survival of salt marsh and salt marsh fringing species. The Stress Gradient Hypothesis (SGH) postulates that species interactions shift from competitive to facilitative as stress levels increase and predicts that (a) the frequency …

Phylogenetically Novel Species Are More Successful Due To High Competitive Ability At Local And Regional Scales, Amy C. Patterson

Undergraduate Research Symposium Posters

Invasive species are widely considered to be a major threat to native biodiversity, however some studies suggest that exotic species seldom cause the extinction of native species, and may even increase biodiversity at some spatial scales. This leads to the question of whether exotic plant species that have naturalized to a new range are biologically distinct from their native counterparts. Here, we chose one common native and one common exotic plant species from each of five plant families, and evaluated their growth over one growing season for two proposed mechanisms of biological invasion. We evaluated the Enemy Release Hypothesis (ERH), …

Evolution And Ecology Of Two Iconic Australian Clades: The Meliphagidae (Birds) And The Hakeinae (Plants), Eliot Trimarchi Miller

Dissertations

The first part of this dissertation explores the evolution of two iconic groups of species through Australian climate space: the Meliphagidae, or honeyeaters, which are primarily nectar-feeding birds, and the Hakeinae, a section of the plant family Proteaceae. Both groups are inferred to have had their origins in Gondwanan rainforests that were widespread across Australia 45 million years ago and then diversified into more arid environments as the continent’s climate became more arid. Accordingly, dry environments are inhabited by closely related (phylogenetically clustered) sets of species, although, in contrast to the honeyeaters, Hakeinae communities are characterized by more localized diversification. …

Behavior Of Pollinators That Share Two Co-Flowering Wetland Plant Species, Joshua R. Morris

Williams Honors College, Honors Research Projects

Abstract:

Intermixed, co-flowering plant species often attract the same pollinators and may therefore compete for pollinator visits. Mimulus ringens and Verbena hastata are sympatric wetland plants that flower in synchrony and share many pollinators, the most common being bumblebees. The possibility of competition between these two plant species led to this observational study tracking pollinator movements in an area intermixed with both M. ringens and V. hastata. We identified pollinator species and tracked them as they visited flowers and moved from plant to plant. Smaller bees seemed to prefer the smaller flowers present on the V. hastata, and …

Wolf-Cougar Co-Occurrence In The Central Canadian Rocky Mountains, Ellen Brandell

Undergraduate Theses, Professional Papers, and Capstone Artifacts

Cougars and wolves are top carnivores that influence the dynamics of an ecosystem, including prey behavior and dynamics, and interspecific competition. Studies about the interactions between wolves and cougars typically find wolves are dominant competitors to cougars. We examined single-species, single-season occupancy models and co-occurrence models of wolves and cougars in the Central Canadian Rocky Mountains to understand interactions between these two species on a grand landscape. Data was collected from 2012-2013 using remote wildlife cameras and separated into seasons. Naïve occupancy estimates were larger for wolves in both seasons, but both species had smaller ranges in winter. There were …