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Fish And Invertebrate Community And Trophic Structure In The Gulf Of Mexico Coastal Plains Watersheds Across Varying Hydrologic Connectivity., Erin Elizabeth Thayer

LSU Doctoral Dissertations

Subtropical Northern Gulf of Mexico coastal plains watersheds tend to have mild seasonal temperature, low topography, and fine, mostly homogenous substrate sizes; these watersheds may not follow fish and invertebrate community patterns predicted by established lotic paradigms because those paradigms tend to describe communities in either temperate or tropical regions. However, the bases of most generally accepted lotic paradigms involve evaluation of allochthonous and autochthonous contributions to lotic ecosystems via three hydrologic connectivity dimensions including vertical (hyporheic and shallow groundwater), lateral (floodplain), and longitudinal (upstream and downstream). My dissertation goals were to explore these three dimensions within Louisiana coastal plains …

Evolution Of Freshwater Fishes In The Northern Neotropics, Diego Elias

LSU Doctoral Dissertations

The northern Neotropics (NN) represents one of the most geologically-complex regions on the planet, composed of island-like geological blocks that have undergone multiple episodes of isolation and connectivity at various geological times. The riverscapes of the NN harbor a unique assemblage of freshwater fishes. In contrast to the freshwaters systems of South America, which are dominated by ostariophysan lineages, the aquatic systems of the NN are dominated by lineages of two families: Cichlidae (cichlids) and Poeciliidae (livebearers). It has been suggested that the geologically complex nature of the region allowed ancestors of cichlids and livebearers to colonize and radiate within …

Insights Into The Speciation Process From Genomic And Phenotypic Analysis Of An Avian Hybrid Zone In Amazonia, Glaucia Christina Del-Rio

LSU Doctoral Dissertations

Understanding the outcome of secondary contact is essential to shed light on the mechanisms governing species formation and maintenance. In Amazonia, closely related bird taxa with limited dispersal abilities are often separated by rivers, which presumably act as dispersal barriers. However, at the headwaters, rivers cease to be dispersal barriers, and this generates opportunities for secondary contact. In my dissertation, I studied genomic mechanisms associated with phenotypic differences, mitochondrial DNA structure, and putative reproductive barriers between two hybridizing Amazonian bird species in the genus Rhegmatorhina, a group of antbirds that find their arthropod prey exclusively by following army-ant swarms. …

Breeding Ecology Of Mottled Ducks In Southwestern Louisiana, Elizabeth Sophia Bonczek

LSU Doctoral Dissertations

Mottled ducks are a resident species found in the southern United States that rely on coastal marsh and associated habitat to fulfill the needs of the entirety of their annual cycle. Population monitoring has revealed declines in western Gulf Coast (WGC) mottled ducks since 2008. Mottled duck populations are influenced by survival and recruitment, and changes in these factors may contribute to population declines. The overarching goal of this project was to identify the mechanisms potentially limiting WGC mottled ducks.

I captured adult female mottled ducks during molt on Rockefeller Wildlife Refuge and adjacent lands in southwestern Louisiana from 2017–2019. …

The Design, Construction, And Testing Of A Recombinant Dna Vaccine For Brucella Abortus And Brucella Melitensis, Stephanie Lynn Korle

LSU Doctoral Dissertations

Brucella spp. are a bacterium that cause brucellosis, a zoonotic disease, which is commonly seen in cattle, sheep, goats, swine, and canines. Brucellosis is a problem worldwide, although it is eradicated in some countries (Garin-Bastuji et al. 1998). The reason for designing recombinant DNA (rDNA) vaccines opposed to utilizing the live-attenuated vaccines on the market is that they cannot be given to pregnant animals without potentially causing abortion, while an rDNA vaccine should be safe for pregnant animals since it does not contain viable bacteria. Also, there are no serological tests that can accurately distinguish between an animal vaccinated …