Life Sciences Commons^™

A Change In Grain? Diet Induced Plasticity In The Generalist Grasshopper Melanoplus Differentialis, Austin M. Culotta

University of New Orleans Theses and Dissertations

Phenotypic plasticity is favored in heterogeneous environments in which alternative phenotypes can exploit alternative resources. However, it’s not clear whether phenotypic plasticity is useful in environments that become more homogenous over an organism’s life cycle. I studied a population of grasshopper Melanoplus differentialis that experiences high resource diversity as nymphs but low resource diversity as adults to determine if individuals can undergo diet-induced morphological plasticity in head shape to increase biting ability and ingestion of hard diets. Insects on a soft diet were larger and had greater bite force than those on a hard diet. Head structures related to chewing …

Legacy Habitat Suitability Of Eastern Oysters (Crassostrea Virginica) In Louisiana: A Prelude To Mississippi River Delta Freshwater Diversions, Tasia Mv Denapolis

University of New Orleans Theses and Dissertations

The Louisiana oyster industry is greatly impacted by freshwater and sediment diversions that are part of the effort to restore the state’s coastline. A habitat suitability index (HSI) proposes species-habitat relationships that can be instrumental in creating impact assessments and suitability predictions for management as new diversions are implemented. An oyster (Crassostrea virginica) HSI was developed using three variables crucial to oyster sustainability: average annual salinity, minimum monthly salinity, and average salinity during the spawning season. These Legacy HSI visualizations show annual fluctuations in the distribution of zones suitable for oyster cultivation prior to proposed diversions in Pontchartrain …

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 …

Genetic Diversity In An Invasive Clonal Plant? A Historical And Contemporary Perspective, Elliot D. Weidow

University of New Orleans Theses and Dissertations

Introduced populations of Eichhornia crassipes (Pontederiaceae) possess extremely low levels of genetic diversity due to severe bottleneck events and clonal reproduction. While populations elsewhere have been well studied, North American populations of E. crassipes remain understudied. We used Amplified Fragment Length Polymorphism markers to assess genetic diversity and population structure in North American E. crassipes populations. Patterns of diversity over the past fifty years were analyzed using herbarium specimens. Furthermore, we sampled populations across the Gulf Coast of the United States throughout a year to determine contemporary genetic diversity and assess potential seasonal effects. Genetic diversity was found to be …

Characterization Of Genes Involved In The Biosynthesis Of Phycoerythrin I And Ii In Cyanobacteria, Adam Nguyen

University of New Orleans Theses and Dissertations

Cyanobacteria are photosynthetic prokaryotes that able to produce oxygen. They have light harvesting complexes called phycobilisomes (PBS). PBS are generally composed of an allophycocyanin core with phycocyanin and phycoerythrin rods connected to the core. PBS are able to efficiently harvest light energy from different wavelengths of visible light due to the evolution of PBP. Phycoerythrin has five chromophores that are attached to six cysteine residues and is essential for efficient green light capture and transfer of energy for use in photosynthesis. The attachment of these chromophores to PBP is facilitated by enzymes known as bilin lyases.

In this study, we …

Zooplankton Community Composition In Natural And Artificial Estuarine Passes Of Lake Pontchartrain, Louisiana, Arnaud Kerisit

University of New Orleans Theses and Dissertations

I assessed the composition of zooplankton communities at the three tidal inlets connecting Lake Pontchartrain to Lake Borgne and subsequently to the Gulf of Mexico. The objectives of my research were to better understand the factors contributing to both spatial and temporal differences in zooplankton communities at the three locations. Monthly samplings of the neuston were conducted from September 2009 until April 2011 and then again from September 2012 until May 2013. Sampling consisted of triplicate tows using SeaGear “Bongo” nets. Water quality data along with water turbidity were recorded at each site and during each sampling effort. All specimens …

Analysis Of Temperature And Salinity Effects On Growth And Mortality Of Oysters (Crassostrea Virginica) In Louisiana, Troy Sehlinger

University of New Orleans Theses and Dissertations

Salinity (S) and temperature (T) control every facet of the eastern oyster (Crassostrea virginica) life cycle, principally reproduction, development, growth, and mortality. Previous studies conducted in in the Breton Sound (BR) and Barataria (BA) estuaries have reported differences in growth and mortality rates between the basins. In the present study, environmental conditions were synchronized to compare growth and mortality rates between basins at similar combinations of T and S. Results indicate that when T and S are the same (synchronized), seasonal oyster growth and mortality rates differ between BR and BA. Seasonal analyses revealed that as salinities increased …