Haemosporidian parasites are the agents of malaria. Countless vertebrates are affected by haemosporidians each year. Haemosporidians have been shown to be evolving at rapid rates; leading to new species of haemosporidians being discovered and new host associations being made. Adaptive molecular evolution was detected in an important hemoglobin degradation gene, falcilysin. At multiple sites across multiple genes involved in important functions signatures of negative selection were detected. The signatures of selection across non-hemoglobin degradation genes were indicative of evolutionary conservation when compared to the more variable hemoglobin degradation genes. This is probably due to the important role the hemoglobin degradation genes play in haemosporidian metabolism. A survey of local passerines detected a parasite prevalence rate of 57%. This included three genera of haemosporidians detected across six lineages and two more distantly related sequences. Leucocytozoon was detected for the first time in Mississippi songbirds, indicating the importance of surveying for understanding haemosporidian evolution and range.

No description available.

It is now widely accepted that modern day birds originated from the clade Theropoda represented by bipedal carnivorous dinosaurs that thrived between the late Triassic and Cretaceous period. New research illustrates how the evolutionary assembly of the avian body plan began in these theropods with small fore limbs, large hind limbs and stiff tails, and progressed through a series of increasingly bird-like, transitional anatomical stages. There is also a great deal of homoplasy among dinosaurs however, or evolution of the same traits in distantly related groups, which makes it even more difficult to pinpoint the phylogenetic relationships among theropods. A limited fossil record and confusing temporal inconsistency has also led paleontologists and ornithologists alike to dismiss this crucial connection. They often attribute the origin of birds instead to a basal archosaur, ancestor to both dinosaurs and crocodilians. However the recent discoveries of feathered non-avian theropods, especially from the Late Jurassic and Early Cretaceous of Liaoning, China may finally lay the argument to rest. The scientific community has remained especially divided over to what degree feathers and other flight characteristics are present amongst the advanced theropods, and Dinosauria in general. Understanding this distinction helps separate each species into separate clades along the cloudy phylogenetic timeline as a function of feather development, and therefore offers insight into where they initially became functional for flight. Because fossils depicting defined integumental structures have been recently uncovered by the hundreds over the last 20 years, there is more evidence of this transition than ever. Through studies of theropod and avian physiology, we can gain more insight into the macroevolutionary principles and selective pressures that led dinosaurs to take to the sky.

Bottomland hardwood forests (BHF) are a disappearing habitat of importance to numerous migratory and non-migratory birds of conservation concern. Thus, understanding variables of bottomland hardwood forests that affect avian assemblage patterns are of great interest. I examined factors influencing avian assemblage and guild patterns in BHF of Noxubee National Wildlife Refuge in east-central Mississippi by conducting winter and spring fixed-radius avian point counts and vegetation surveys from 2002 ? 2004. The goals of this project were to 1) determine effects of greentree reservoir (GTR) management on breeding and wintering non-game bird community structure, 2) test hypotheses regarding plant structural complexity and avian assemblage patterns, and 3) examine the effects of landscapes on local bird assemblages within BHF. Greentree reservoirs have subtle effects on avian communities. Sites within GTRs, sites in BHF adjacent to GTRs, and random, unimpounded BHF sites differed significantly in breeding bird diversity, richness, and evenness. However, the patterns exhibited were a decreasing continuum of these variables with sites peripheral to GTRs demonstrating intermediate values. No differences were found among abundance, conservation status, or habitat specialization of breeding birds. Guild parameters did not differ except for a decreasing continuum in species richness among unimpounded BHF, BHF to GTRs, and GTR sites. The canopy nesting and ground gleaning foraging guilds were the only guilds found to differ among sites. Patterns could indicate that given the inherent structural variation of BHF, GTRs are within the expected range of variation, or GTR management could be indirectly affecting the surrounding landscape. GTR management did not affect community parameters for wintering birds, and only the bark gleaning foraging guild varied among sites (higher in GTRs). These results reflect the ubiquitous nature of wintering birds in east-central Mississippi forests. There was direct support for the structural vertical heterogeneity hypothesis; however, regression analyses of principal component scores derived from sixty structural descriptor metrics suggest that avian communities and guilds are more directly influenced by overall local plant structural complexity, as predicted by the spatial heterogeneity hypothesis. Avian community and guild parameters did not differ among the three landscape contexts defined by 1,000 and 1,500m buffers.

These recent events of H1N1 flu outbreak illustrate the potential ramifications of infectious diseases on modern society and how society responds to these threats. This thesis addresses the specific case of avian influenza in U.S. poultry production. By building an expected utility maximization model for integrators contracting with growers of varying bio-secure levels, one can investigate the relationship between the bio-secure choice of the poultry industry and their production performance. The model is empiricized using the Phoon, Quek, and Huang (PQH) simulation technique to conduct numerical analysis. The model selects the optimal percentage of bio-secure farms for the integrators to contract, output price reductions due to disease outbreak, and different probabilities of disease outbreak. Results allow the examination of whether alternative USDA/APHIS indemnification rules can sufficiently influence integrators willingness to improve their bio-security level.

No description available.

No description available.

No description available.

No description available.

No description available.