Speciation genetics in two pairs of high-latitude, migratory bird taxa

Thesis (M.S.) University of Alaska Fairbanks, 2013I investigated and characterized the divergence of two pairs of putatively young, high-latitude, migratory bird taxa with data from mitochondria) and nuclear DNA. I chose pairs exhibiting natural history attributes suggesting divergence scenarios that probably did not involve strict allopatry. First, I examined Pluvialis dominica and P. fulva, migratory plover species with a largely parapatric breeding range in Beringia. Secondly, I examined Aegolius acadicus acadicus and A. a. brooksi, a subspecies pair of owls where one subspecies (brooksi) is endemic to Haida Gwaii, Canada, a location where subspecies acadicus occurs during migration, resulting in cyclic sympatry (heteropatry) with brooksi. Using mtDNA sequence data and AFLPs I made inferences about population parameters, inferred the likely number of populations, and sought evidence of selection. Gene flow was very low in both pairs. The plovers are much older than was anticipated (1.8 Mybp), although hybridization does occur. Evidence for parapatric or speciation with gene flow scenarios was not found in the plovers, perhaps because the speciation event occurred far in the past. The owl's divergence date was relatively young (~16,000 ybp). Some evidence was found suggesting that heteropatric divergence contributed to the owl's differentiation, although the process could also have reinforced differences acquired largely in allopatry.1. Speciation in the migratory shorebird lineage, the Pluvialis domina-fulva complex -- 1.1. Abstract -- 1.2. Introduction -- 1.3. Materials and methods -- 1.3.1. Mitochondrial sequence data and sampling -- 1.3.2. Amplified fragment length polymorphisms data and sampling -- 1.3.3. Genetic differentiation and population structure -- 1.3.4. Divergence time, effective population size, and gene flow -- 1.3.5. Genetic diversity and selection -- 1.4. Results -- Genetic differentiation and population structure --1.4.2. Divergence time, effective population size, and gene flow -- 1.4.3. Genetic diversity and selection -- 1.5. Discussion -- 1.6. Literature cited -- Appendix 1.A. -- Appendix 1.B. -- 2. Heteropatric differentiation in the Haida Gwaii owl, Aegolius acadicus brooksi -- 2.1. Abstract -- 2.2. Introduction -- 2.3. Materials and methods -- 2.3.1. Mitocholdrial sequence data and sampling -- 2.3.2. Amplified fragment length polymorphisms data and sampling -- 2.3.3. Genetic differentiation and population structure -- 2.3.4. Divergence time, effective population size, and gene flow -- 2.3.5. Genetic diversity and selection -- 2.4. Results -- 2.4.1. Genetic differentiation and population structure -- 2.4.2. Divergence time, effective population size, and gene flow -- 2.4.3. Genetic diversity and selection -- 2.5. Discussion -- 2.6. Literature cited -- Appendix 2.A. -- Appendix 2.B. -- General conclusion

Spotted Seals, Phoca largha, in Alaska

The worldwide literature on management of spotted seals, Phoca largha, was reviewed and updated, and aerial surveys weref lown in 1992 and 1993 to determine the species' distribution and abundance in U.S. waters. In April, spotted seals were found only in the Bering Sea ice front. In June, they were seen along deteriorating ice floes and fast ice in Norton Sound. Surveys along most of Alaska's western coast in August and September found over 2,500 spotted seals in Kuskokwim Bay and concentrations of 100-400 seals around Nunivak Island, Scammon Bay, Golovnin Bay/Norton Sound, Cape Espenberg/Kotzebue Sound, and Kasegaluk Lagoon. All of these sites have been used by spotted seals in the past. The sum of the highest counts, irrespective of year, was 3,570 seals (CV =0.06). This is not an abundance estimate for all spotted seals in the Bering Sea, because it does not account for animals in the water, and we did not survey the Asian coast and some islands. Also, spotted seals and harbor seals, Phoca vitulina, are too similar in appearance to be identified accurately from the air, so our results probably include a mix of these species where their ranges overlap

SEI rover solar-electrochemical power system options

A trade study of power system technology for proposed lunar vehicles and servicers is presented. A variety of solar-based power systems were selected and analyzed for each. The analysis determined the power system mass, volume, and deployed area. A comparison was made between periodic refueling/recharging systems and onboard power systems to determine the most practical system. The trade study concluded that the power system significantly impacts the physical characteristics of the vehicle. The refueling/recharging systems were lighter and more compact, but dependent on availability of established lunar base infrastructure. Onboard power systems pay a mass penalty for being fully developed systems

Does Unconscious Thought Outperform Conscious Thought On Complex Decisions? A Further Examination

Two experiments examined the benefits of unconscious thought on complex decisions (Dijksterhuis, 2004). Experiment 1 attempted to replicate and extend past research by examining the effect of providing reasons prior to rating the options. Results indicated no significant differences between the conditions. Experiment 2 attempted to replicate the findings of Dijksterhuis, Bos, Nordgren, and van Baaren (2006) and determine if a memory aid could overcome the limitations of conscious thought on complex tasks. Results revealed that a memory aid improved decisions compared to the conscious thought condition. Participants in the unconscious thought condition did not perform significantly better than did participants in the conscious thought condition

Design of small Stirling dynamic isotope power system for robotic space missions

Design of a multihundred-watt Dynamic Isotope Power System (DIPS) based on the U.S. Department of Energy (DOE) General Purpose Heat Source (GPHS) and small (multihundred-watt) free-piston Stirling engine (FPSE) technology is being pursued as a potential lower cost alternative to radioisotope thermoelectric generators (RTG's). The design is targeted at the power needs of future unmanned deep space and planetary surface exploration missions ranging from scientific probes to Space Exploration Initiative precursor missions. Power level for these missions is less than a kilowatt. Unlike previous DIPS designs which were based on turbomachinery conversion (e.g. Brayton), this small Stirling DIPS can be advantageously scaled down to multihundred-watt unit size while preserving size and mass competitiveness with RTG's. Preliminary characterization of units in the output power ranges 200-600 We indicate that on an electrical watt basis the GPHS/small Stirling DIPS will be roughly equivalent to an advanced RTG in size and mass but require less than a third of the isotope inventory

Extinction efficiencies from DDA calculations solved for finite circular cylinders and disks

One of the most commonly noted uncertainties with respect to the modeling of cirrus clouds and their effect upon the planetary radiation balance is the disputed validity of the use of Mie scattering results as an approximation to the scattering results of the hexagonal plates and columns found in cirrus clouds. This approximation has historically been a kind of default, a result of the lack of an appropriate analytical solution of Maxwell's equations to particles other than infinite cylinders and spheroids. Recently, however, the use of such approximate techniques as the Discrete Dipole Approximation has made scattering solutions on such particles a computationally intensive but feasible possibility. In this study, the Discrete Dipole Approximation (DDA) developed by Flatau (1992) is used to find such solutions for homogeneous, circular cylinders and disks. This can serve to not only assess the validity of the current radiative transfer schemes which are available for the study of cirrus but also to extend the current approximation of equivalent spheres to an approximation of second order, homogeneous finite circular cylinders and disks. The results will be presented in the form of a single variable, the extinction efficiency

Design of multihundredwatt DIPS for robotic space missions

Design of a dynamic isotope power system (DIPS) general purpose heat source (GPHS) and small free piston Stirling engine (FPSE) is being pursued as a potential lower cost alternative to radioisotope thermoelectric generators (RTG's). The design is targeted at the power needs of future unmanned deep space and planetary surface exploration missions ranging from scientific probes to SEI precursor missions. These are multihundredwatt missions. The incentive for any dynamic system is that it can save fuel which reduces cost and radiological hazard. However, unlike a conventional DIPS based on turbomachinery converions, the small Stirling DIPS can be advantageously scaled to multihundred watt unit size while preserving size and weight competitiveness with RTG's. Stirling conversion extends the range where dynamic systems are competitive to hundreds of watts (a power range not previously considered for dynamic systems). The challenge of course is to demonstrate reliability similar to RTG experience. Since the competative potential of FPSE as an isotope converter was first identified, work has focused on the feasibility of directly integrating GPHS with the Stirling heater head. Extensive thermal modeling of various radiatively coupled heat source/heater head geometries were performed using data furnished by the developers of FPSE and GPHS. The analysis indicates that, for the 1050 K heater head configurations considered, GPHS fuel clad temperatures remain within safe operating limits under all conditions including shutdown of one engine. Based on these results, preliminary characterizations of multihundred watt units were established

Comparison of dynamic isotope power systems for distributed planet surface applications

Dynamic isotope power system (DIPS) alternatives were investigated and characterized for the surface mission elements associated with a lunar base and subsequent manned Mars expedition. System designs based on two convertor types were studied. These systems were characterized parametrically and compared over the steady-state electrical output power range 0.2 to 20 kWe. Three methods of thermally integrating the heat source and the Stirling heater head were considered, depending on unit size. Figures of merit were derived from the characterizations and compared over the parametric range. Design impacts of mission environmental factors are discussed and quantitatively assessed

SEI power source alternatives for rovers and other multi-kWe distributed surface applications

To support the Space Exploration Initiative (SEI), a study was performed to investigate power system alternatives for the rover vehicles and servicers that were subsequently generated for each of these rovers and servicers, candidate power sources incorporating various power generation and energy storage technologies were identified. The technologies were those believed most appropriate to the SEI missions, and included solar, electrochemical, and isotope systems. The candidates were characterized with respect to system mass, deployed area, and volume. For each of the missions a preliminary selection was made. Results of this study depict the available power sources in light of mission requirements as they are currently defined