Life Sciences Commons^™

Understanding The Impacts Of Current And Future Environmental Variation On Central African Amphibian Biodiversity, Courtney A. Miller

University of New Orleans Theses and Dissertations

Global climate change is projected to impact multiple levels of biodiversity by imposing strong selection pressures on existing populations, triggering shifts in species distributions, and reorganizing entire communities. The Lower Guineo-Congolian region in central Africa, a reservoir for amphibian diversity, is predicted to be severely affected by future climate change through rising temperatures and greater variability in rainfall. Geospatial modelling can be used to assess how environmental variation shapes patterns of biological variation – from the genomic to the community level – and use these associations to predict patterns of biological change across space and time. The overall goal of …

Coastal Wetland Dynamics Under Sea-Level Rise And Wetland Restoration In The Northern Gulf Of Mexico Using Bayesian Multilevel Models And A Web Tool, Tyler Hardy

Master's Theses

There is currently a lack of modeling framework to predict how relative sea-level rise (SLR), combined with restoration activities, affects landscapes of coastal wetlands with uncertainties accounted for at the entire northern Gulf of Mexico (NGOM). I developed such a modeling framework – Bayesian multi-level models to study the spatial pattern of wetland loss in the NGOM, driven by relative RSLR, vegetation productivity, tidal range, coastal slope, and wave height – all interacting with river-borne sediment availability, indicated by hydrological regimes. These interactions have not been comprehensively investigated before. I further modified this model to assess the efficacy of restoration …

Spatial Distribution And Stock-Recruitment Analysis Of The Atlantic Surfclam, Spisula Solidissima, In The Mid-Atlantic Bight And On Georges Bank, Jeremy Timbs

Master's Theses

Atlantic surfclams, Spisula solidissima, are long-lived bivalve molluscs with dispersive larval stages. Surfclam patchiness throughout the U.S. Exclusive Economic Zone (EEZ) has declined from the 1980’s to the present in all assessed regions (Delmarva, New Jersey, Long Island, Southern New England, and Georges Banks). Warming of Mid-Atlantic bottom waters is driving the surfclam stock into new habitat and extirpating the surfclams from nearshore areas. Based on a species distribution function model, the small surfclams appear to inhabit a greater area than the large market-size surfclams across the entire stock. The wider distribution of recent recruits relative to the fishable …

Direct And Indirect Controls On Bee Community Composition, Caroline Marie Devan

Dissertations

Bees are important pollinators, critical for the continued survival of plants in both natural and agricultural ecosystems. Diverse bee communities have been shown to increase richness in plant communities and plant reproduction depends upon bee community richness. Yet there is growing concern that pollinators, especially bees, are declining globally. This dissertation focuses on evaluating the mechanisms responsible for bee community composition in order to promote bee conservation in natural systems and their restoration in human-dominated urban and agricultural landscapes.

Bee populations are impacted directly by three things: floral resources, nesting resources and risk, primarily from natural enemies. Bees are indirectly …

Linking Climate Change And Mortality In Piñon-Juniper Woodlands, From Leaf To Ecosystem, Amanda I. Liebrecht

Biology ETDs

As global climate changes, the Southwestern US is predicted to experience more frequent and intense drought events. Extreme droughts can drive decreases in both physiological and ecosystem function, and can result in widespread tree mortality. Piñon-juniper (PJ) woodlands are a prevalent ecosystem in the region, co-dominated by two tree species, piñon (Pinus edulis) and juniper (Juniperus monosperma). Drought-induced piñon mortality has occurred over the past few decades, coinciding with outbreaks of a piñon-specific bark beetle. Piñon and juniper have different hydraulic strategies (isohydry and anisohydry, respectively) that should affect the way each species responds to drought. …

Phenology Of A Southern Population Of Mountain Pine Beetle (Dendroctonus Ponderosae), Anne Elise Mcmanis

All Graduate Theses and Dissertations, Spring 1920 to Summer 2023

Mountain pine beetle (Dendroctonus ponderosae, Hopkins) is a major disturbance agent in pine ecosystems of western North America. Adaptation to local climates has resulted in primarily univoltine (one generation per year) generation timing across a thermally diverse latitudinal gradient. We hypothesized that this pattern in total development time is shaped by selection for slower developmental rates, altered developmental thresholds, or oviposition rates in southern populations inhabiting warmer climates. To investigate traits responsible for latitudinal differences we measured lifestage-specific development of southern mountain pine beetle eggs, larvae and pupae across a range of temperatures. We also describe and model …