Ecology and Evolutionary Biology Commons^™

Intraguild Predation: Interactions Between Predators, Pathogens, And Their Shared Resources In Crop Pest Communities, Andrew Jason Flick

LSU Doctoral Dissertations

Crop pest management requires an understanding of the complex interactions among pest species that potentially damage crop yield and species that may be crucial for controlling pest species outbreaks. For example, predators, parasitoids, and pathogens are constantly interacting via their shared prey or hosts. Predators may prefer infected prey, which can be easier to catch; however, infected prey may be less nutritious or even lethal for predators. These interactions then dictate the short-term dynamics of host and pathogen as well as between prey and predator. "How these dynamics change as the species in the system change either empirically or theoretically?" …

Changing Land-Use From Pinus Elliottii To Eucalyptus Bentamii In Southwest Louisiana Affects Understory Vegetation Richness, Diversity, And Functional Diversity Patterns, Andrea De Stefano

LSU Doctoral Dissertations

In the Western Gulf region of the United States cold-tolerant eucalyptus have been explored as pulpwood feedstock. However, non-native plantations may alter understory species diversity, modifying environmental conditions and soil characteristics. Few studies have compared eucalyptus plantations with other ecosystems to understand the impacts of converting these land uses on understory vegetation in the United States. Three plantations were selected: (1) slash pine (Pinus elliottii) established in 2008, (2) slash pine established in 2013, and (3) and Camden white gum (Eucalyptus benthamii) established in 2013. The objectives of this study were to: (1) investigate potential changes …

Speciation And Hybridization In Jamaican-Endemic Streamertail Hummingbirds (Trochilus Polytmus And T. Scitulus), Caroline D. Judy

LSU Doctoral Dissertations

Streamertails hummingbirds (Trochilus polytmus and T. scitulus) are recently diverged sister taxa that appear to have speciated in situ on the island of Jamaica. They are distinguished by male bill color, a secondary sexual trait that is coral red in T. polytmus and jet black in T. scitulus. They hybridize in a narrow zone where their ranges meet in eastern Jamaica. In Chapter 2, I performed a formal population survey of T. scitulus to determine the size of the population, which was unknown. I determined that the total population contains well over 100,000 individuals despite its limited …

An Evaluation Of Sciaenid Growth In The Gulf Of Mexico, Shane Flinn

LSU Master's Theses

Growth models estimate life history parameters that are used in the management of fisheries stocks. The most commonly used growth model in fisheries is the von Bertalanffy growth model (VBGM), yet it has been shown to provide a poor fit for length-at-age data of some species and other models exist. I reviewed 196 peer-reviewed age and growth studies and 50 NOAA stock assessments to examine temporal trends in the use of growth models and model selection in fisheries. I found that the use of multi-model frameworks has increased since the year 2000 and information theoretic approaches are replacing goodness-of-fit and …

A Review Of Current Knowledge Concerning The Breeding And Summer Distribution Of The Cordilleran Flycatcher (Empidonax Occidentalis) In Mexico, Harold F. Greeney, Matthew J. Miller, Charles Van Riper Iii

Occasional Papers of the Museum of Natural Science, Louisiana State University

The Cordilleran Flycatcher (Empidonax occidentalis) is one of many North American birds whose distribution crosses the US–Mexican border and for which little is presently known about summer distribution and breeding biology south of this border. In addition, the Cordilleran Flycatcher presents ornithologists with a number of challenging questions surrounding its taxonomy, migration, distribution, population structure, and species limits. In particular, there remains a good deal of uncertainty concerning the species-level relationships, seasonal movements, and the wintering and breeding distributions of both recognized subspecies of Cordilleran Flycatcher in Mexico. Using field observations, a thorough review of the literature, and …

Determining The Drivers Of Anti-Tropical Distributions Across The Fish Tree Of Life, William Benton Ludt

LSU Doctoral Dissertations

Anti-tropical distributions are those where populations of a single species, or multiple closely related taxa, are distributed outside of, and on opposing sides of, the tropics. These latitudinally disjunct distributions have been noted for over a century. Despite this long history of interest, little has been concluded regarding the actual mechanisms that drive this pattern, with several prominent hypotheses competing with one another in the literature. Here I review the proposed drivers of anti-tropicality, and subsequently test them using fishes with a variety of life history and taxonomic differences. This includes (1) a temperately restricted family with anti-tropical distributions – …

Impact Of Temperature, Plant Species, And Sorghum Cultivar On The Population Dynamics Of Melanaphis Sacchari, Monique Ferreira De Souza

LSU Doctoral Dissertations

Sugarcane aphid, Melanaphis sacchari Zehner, is now widely established in sorghum, Sorghum bicolor L., production areas of the United States and is an important economic pest. However, detailed studies of temperature, host range and plant resistance effects on the biology and population parameters of the M. sacchari biotype responsible for the sorghum outbreak in the United States have not been performed previously. Therefore, the present study aimed to investigate: 1) How temperatures affect M. sacchari 2) M. sacchari interaction with host plants 3) M. sacchari interaction with sorghum genotypes. The response of M. sacchari to six different constant temperatures (15, …

Computational Analysis Of Papionini Evolution Using Alu Insertions, Vallmer Edward Jordan Ii

LSU Doctoral Dissertations

Alu elements are primate specific retrotransposons that have remained active throughout the course of primate evolution. As a result of this sustained mobilization. Alu elements are present in greater copy number in primate genomes than any other transposable element. An average of over one million Alu elements has been identified in every sequenced haplorrhine genome to date. These characteristics qualify Alu elements as ideal characters for studying evolutionary relationship among primates.

The increasing availability of whole genome sequencing data presents novel challenges and opportunities for comparative genomic analyses. Genomic data is now publicly available for most primate species. Such an …

Analysis Of Submerged Aquatic Vegetation Resources Across The Northern Gulf Of Mexico: Communities And Biomass, Eva R. Hillmann

LSU Doctoral Dissertations

Submerged aquatic vegetation (SAV) provides many critical ecosystem services, yet we lack basic information on SAV assemblages, biomass and diversity across expansive coasts such as the northern Gulf of Mexico (nGoM). This research investigated SAV along the nGoM from 2013-2015 examining (1) inter-annual variation in SAV assemblages and biomass across salinity zones and gulf coast eco-regions (Texas Mid-Coast, Texas/LA Chenier Plain, Louisiana Delta, MS/AL), (2) intra-annual variation in SAV assemblages and biomass across salinity zones, (3) response of two species, Ruppia maritima and Myriophyllum spicatum, to salinity and light regimes, and (4) estimated organic carbon stock and storage of …

Evolution Of Alu Elements In The Saimiri And Papio Lineages Of Primates, Jasmine Nicole Brown Baker

LSU Doctoral Dissertations

Alu elements are approximately 300 base pair (bp) primate specific non- autonomous retrotransposons. Alu elements, a short interspersed element (SINE), account for high copy numbers in all primate genomes. Numerous Alu element subfamilies have undergone varying degrees of activity and amplification within primates. Identification of these subfamilies has proved to be very informative in elucidating phylogenies and as phylogenomic markers. Squirrel monkeys, genus Saimiri, are one of the most well-known neotropical primates and the second most commonly used laboratory monkey. Squirrel monkey species diverged approximately 1.5 million years ago and are native to South America. Despite being well-known, there …

Sediment And Plant Dynamics In A Degrading Coastal Louisiana Landscape, Glenn Michael. Suir

LSU Doctoral Dissertations

Alterations to Louisiana’s river systems and local hydrology have resulted in reduced freshwater, sediment, and nutrient inputs into wetland landscapes, causing significant negative impacts on marsh productivity and stability. To combat these losses many restoration projects have been constructed or planned throughout coastal Louisiana. Typical goals of wetland restoration efforts are to conserve, create, or enhance wetland form, and to achieve wetland function that approaches natural conditions. Failure to adequately maintain wetland elevation and hydrology can have serious implications on sedimentation and vegetation processes, which significantly reduces the likelihood of reaching structural and functional targets. Measures of wetland condition have …

The Tensile Root Strength Of Emergent Coastal Macrophytes, Lauris Olivia Hollis

LSU Doctoral Dissertations

Spartina patens is a dominant emergent macrophyte in fresh, intermediate, and brackish marshes along the Atlantic and Gulf coasts of United States where its biomechanical properties are a key component of wetland health and resilience. Its root biomass and tensile root strength are essential for anchorage, erosion protection, and are important determinants of soil strength. Nutrients and the herbicide atrazine are suspected of negatively impacting this wetland plant and others. The objectives of this study were to: 1) ascertain the tensile root strength of five emergent coastal macrophytes in coastal estuaries, and 2) test the effects of nutrient addition, atrazine …

First Record Of The Non-Native Pacu, Piaractus Brachypomus, In Lago Petén-Itzá, Guatemala, Central America, Diego J. Elias, Susan F. Mochel, Prosanta Chakrabarty, Caleb D. Mcmahan

Occasional Papers of the Museum of Natural Science, Louisiana State University

We documented the first record of the non-native species Piaractus brachypomus (Characiformes: Serrasalmidae) in Lago Petén-Itzá, Petén, Guatemala. One brined specimen was donated by a local fisherman in San Benito, El Petén. The captured specimen was reportedly collected in the southern basin of the lake. We used the mitochondrial gene cytochrome oxidase I (COI) to validate identity of the specimen. We hypothesize that the local aquarium trade is the most likely source of introduction of the non-native Pacu in Lago Petén-Itzá.

Documentamos el primer registro de la especie no nativa Piaractus brachypomus (Characiformes: Serrasalmidae) en el lago Petén Itzá, Petén, …

Crayfish Harvesting Practices In The Southern Atchafalaya River Basin: Quantitative And Qualitative Assessment Of Harvester Techniques And Hydrologic Connectivity Influence On Harvesting Strategies, Ivan A. Vargas-Lopez

LSU Master's Theses

Fisheries produce important impacts around the world through the exploitation of a wide range of species. In Louisiana, crayfish is the most emblematic crustacean and supports a multi-million industry based on pond culture and harvest from natural habitats. Although the economic value (USD) of wild-harvested crayfish has decreased from 10% to 3% of total crayfish value from 2013 to 2015, wild harvested crayfish are highly desired by many consumers and have a strong socio-cultural importance in Louisiana and other Gulf of Mexico coastal regions. This project evaluated harvesting practices by: 1) field observation and mapping of harvest sites in southwestern …

The Effects Of Tree Plantations And Land Use On Natural Regeneration Of Woody Plants In The Tropics: Diversity, Species Composition, Successional Dynamics, And Functional Traits, John Benjamin Longworth

LSU Doctoral Dissertations

As anthropogenic forests become more common in the tropics, there is a greater need to understand the factors that impact forest succession. I used censuses of woody plants in successional forests to study the effects of prior land use and tree plantations on species composition and richness. First, I tested the hypothesis that communities originating from different land uses were converging in species composition over time. I compared species composition using the Chao-Jaccard similarity index. I observed shifts in the dominant species during the first 30 years of succession, but not convergence of species composition in sites with different land-use …

Determining Bioindicators For Coastal Tidal Marsh Health Using The Food Web Of Larvae Of The Greenhead Horse Fly (Tabanus Nigrovittatus), Devika Rajeev Bhalerao

LSU Master's Theses

The greenhead horse fly Tabanus nigrovittatus Macquart is native to coastal marshlands from Texas to Nova Scotia. The larvae are apex invertebrate predators and their development is dependent on the food web in the soil. Surveillance of T. nigrovittatus after the 2010 Deepwater Horizon oil spill in the Gulf of Mexico showed population crashes of adults in the coastal marshes of East Louisiana near places where oil made landfall, but not in West Louisiana where the oil did not reach. Sediment collection in 2011 from West and East Louisiana revealed larval population crashes in the Eastern coastal region. We hypothesized …

Carbon Dioxide Fluxes And Plants Interactions Across The Succession Of A Created Brackish Marsh In Southwestern Louisiana, Andy T. Muench

LSU Master's Theses

The purpose of this study was to examine: 1) carbon dioxide (CO₂) fluxes in different plant communities in a created and natural brackish marsh and 2) the role of an early colonizing species, Spartina alterniflora, in facilitating or suppressing a later colonizer and higher marsh species, Spartina patens. CO₂ fluxes were measured in four key successional stages: 1) non-vegetated sediment of a newly created marsh; 2) Spartina alterniflora-dominated areas of a newly created marsh; 3) S. alterniflora-dominated natural marsh; and 4) Spartina patens- dominated natural marsh. Spartina alterniflora-dominated areas were sinks for …