Climate mediates geographic patterns in ecoevolutionary plant-soil dynamics

Unifying ecosystem ecology and evolutionary biology promises a more complete understanding of the processes that link different levels of biological organization across space and time. Feedbacks across levels of organization link theory associated with eco-evolutionary dynamics, niche construction, and the geographic mosaic theory of co-evolution. The work presented in this dissertation directly extends the integration of eco-evolutionary dynamics by 1) highlighting our current knowledge of eco-evolutionary feedbacks in ecosystems, to provide an improved synthesis and foundation for understanding the interplay between biodiversity and ecosystem function through an eco-evolutionary lens; 2) examining the hypothesis that climate-driven evolution of plant traits will have downstream consequences for associated soil microbiomes and ecosystem function across the landscape; and 3) examining genetically-based plant-soil feedback at the landscape scale to understand how variation in climate, soil microbiome function, and tree-driven soil conditioning interact to influence phenotypic variation in bud break phenology. The findings from this dissertation provides evidence that understanding the natural variation in genetic components of both above- and belowground portions of the plant-soil linkage are important for predicting patterns of divergence in ecosystem function in a warmer world. Cumulatively, this dissertation extends the field of eco-evolutionary dynamics by highlighting the interplay between ecology and evolution that governs the expression of phenotypes, patterns of community composition, and divergence in ecosystem function at spatial scales rarely appreciated

The Effects of Bison on Cattle Winter Range in the Henry Mountains of South Central Utah: Resolving a Conflict

The American Bison in the Henry Mountains are one of the last free-roaming, genetically pure herds of bison remaining in North America. Over the last decade, the herd has used a cattle winter range during the summer and early fall, creating a conflict between the wildlife officials who manage the bison population, and BLM officials and local ranchers who manage the rangeland

Evolution of the northern KwaZulu-Natal coastal dune cordon : evidence from the fine-grained sediment fraction.

Thesis (M.Sc.)--University of KwaZulu-Natal, Durban, 2001.Abstract available in PDF file

Supersonic aerodynamic characteristics of a circular body Earth-to-Orbit vehicle

The circular body configuration is a generic single- or multi-stage reusable Earth-to-orbit transport. A thick clipped-delta wing is the major lifting surface. For directional control, three different vertical fin arrangements were investigated: a conventional aft-mounted center fin, wingtip fins, and a nose-mounted fin. The tests were conducted in the Langley Unitary Plan Wind Tunnel. The configuration is longitudinally stable about the estimated center of gravity of 0.72 body length up to a Mach number of about 3.0. Above Mach 3.0, the model is longitudinally unstable at low angles of attack but has a stable secondary trim point at angles of attack above 30 deg. The model has sufficient pitch control authority with elevator and body flap to produce stable trim over the test range. The model with the center fin is directionally stable at low angles of attack up to a Mach number of 3.90. The rudder-like surfaces on the tip fins and the all-movable nose fin are designed as active controls to produce artificial directional stability and are effective in producing yawing moment. The wing trailing-edge aileron surfaces are effective in producing rolling moment, but they also produce large adverse yawing moment

Subsonic Aerodynamic Characteristics of a Circular Body Earth-to-Orbit Vehicle

A test of a generic reusable earth-to-orbit transport was conducted in the 7- by 10-Foot high-speed tunnel at the Langley Research Center at Mach number 0.3. The model had a body with a circular cross section and a thick clipped delta wing as the major lifting surface. For directional control, three different vertical fin arrangements were investigated: a conventional aft-mounted center vertical fin, wingtip fins, and a nose-mounted vertical fin. The configuration was longitudinally stable about the estimated center-of-gravity position of 0.72 body length and had sufficient pitch-control authority for stable trim over a wide range of angle of attack, regardless of fin arrangement. The maximum trimmed lift/drag ratio for the aft center-fin configuration was less than 5, whereas the other configurations had values of above 6. The aft center-fin configuration was directionally stable for all angles of attack tested. The wingtip and nose fins were not intended to produce directional stability but to be active controllers for artificial stabilization. Small rolling-moment values resulted from yaw control of the nose fin. Large adverse rolling-moment increments resulted from tip-fin controller deflection above 13 deg angle of attack. Flow visualization indicated that the adverse rolling-moment increments were probably caused by the influence of the deflected tip-fin controller on wing flow separation

Cytomegalovirus exploits IL-10–mediated immune regulation in the salivary glands

The salivary glands represent a major site of cytomegalovirus replication and transmission to other hosts. Despite control of viral infection by strong T cell responses in visceral organs cytomegalovirus replication continues in the salivary glands of mice, suggesting that the virus exploits the mucosal microenvironment. Here, we show that T cell immunity in the salivary glands is limited by the induction of CD4 T cells expressing the regulatory cytokine interleukin (IL)-10. Blockade of IL-10 receptor (IL-10R) with an antagonist antibody dramatically reduced viral load in the salivary glands, but not in the spleen. The mucosa-specific protection afforded by IL-10R blockade was associated with an increased accumulation of CD4 T cells expressing interferon γ, suggesting that IL-10R signaling limits effector T cell differentiation. Consistent with this, an agonist antibody targeting the tumor necrosis factor receptor superfamily member OX40 (TNFRSF4) enhanced effector T cell differentiation and increased the number of interferon γ–producing T cells, thus limiting virus replication in the salivary glands. Collectively, the results indicate that modulating effector T cell differentiation can counteract pathogen exploitation of the mucosa, thus limiting persistent virus replication and transmission

Aerodynamic and Aeroelastic Characteristics of a Tension Cone Inflatable Aerodynamic Decelerator

The supersonic aerodynamic and aeroelastic characteristics of a tension cone inflatable aerodynamic decelerator were investigated by wind tunnel testing. Two sets of tests were conducted: one using rigid models and another using textile models. Tests using rigid models were conducted over a Mach number range from 1.65 to 4.5 at angles of attack from -12 to 20 degrees. The axial, normal, and pitching moment coefficients were found to be insensitive to Mach number over the tested range. The axial force coefficient was nearly constant (C(sub A) = 1.45 +/- 0.05) with respect to angle of attack. Both the normal and pitching moment coefficients were nearly linear with respect to angle of attack. The pitching moment coefficient showed the model to be statically stable about the reference point. Schlieren images and video showed a detached bow shock with no evidence of large regions of separated flow and/or embedded shocks at all Mach numbers investigated. Qualitatively similar static aerodynamic coefficient and flow visualization results were obtained using textile models at a Mach number of 2.5. Using inflatable textile models the torus pressure required to maintain the model in the fully-inflated configuration was determined. This pressure was found to be sensitive to details in the structural configuration of the inflatable models. Additional tests included surface pressure measurements on rigid models and deployment and inflation tests with inflatable models