Population Structure and Conservation Genetics of the Oregon Spotted Frog, Rana Pretiosa

The Oregon spotted frog (Rana pretiosa) is one of the most threatened amphibians in the Pacific Northwest. Here we analyzed data from 13 microsatellite loci and 298 bp of mitochondrial DNA in frogs collected from 23 of the remaining R. pretiosa populations in order to (1) assess levels of genetic diversity within populations of R. pretiosa, (2) identify the major genetic groups in the species, (3) estimate levels of genetic differentiation and gene flow among populations within each major group, and (4) compare the pattern of differentiation among R. pretiosa populations with that among populations of R. cascadae, a non-endangered congener that also occurs in Oregon and Washington. There is a strong, hierarchical genetic structure in R. pretiosa. That structure includes six major genetic groups, one of which is represented by a single remaining population. R. pretiosa populations have low genetic diversity (average He = 0.31) compared to R. cascadae (average He = 0.54) and to other ranid frogs. Genetic subdivision among populations is much higher in R. pretiosa than in R. cascadae, particularly over the largest geographic distances (hundreds of kilometers). A joint analysis of migration rates among populations and of effective sizes within populations (using MIGRATE) suggests that both species have extremely low migration rates, and that R. pretiosa have slightly smaller effective sizes. However, the slight difference in effective sizes between species appears insufficient to explain the large difference in genetic diversity and in large-scale genetic structure. We therefore hypothesize that low connectivity among the more widely-spaced R. pretiosa populations (owing to their patchier habitat), is the main cause of their lower genetic diversity and higher among-population differentiation. Conservation recommendations for R. pretiosa include maintaining habitat connectivity to facilitate gene flow among populations that are still potentially connected, and either expanding habitat or founding additional \u27backup\u27 populations to maintain diversity in the isolated populations. We recommend that special consideration be given to conservation of the Camas Prairie population in Northern Oregon. It is the most geographically isolated population, has the lowest genetic diversity (He = 0.14) and appears to be the only remaining representative of a major genetic group that is now almost extinct. Finally, because the six major groups within R. pretiosa are strongly differentiated, occupy different habitat types, and are geographically separate, they should be recognized as evolutionarily significant units for purposes of conservation planning

Population genetics of ranid frogs : investigating effective population size and gene flow

This dissertation focuses on the evolutionary forces of genetic drift and gene flow in frog populations. The balance of these two forces and the force of mutation largely determine the amount of neutral genetic variation within populations as well as the degree of genetic similarity among populations. The stochastic evolutionary change caused by genetic drift can be quantified through the use of the effective population size (N[subscript e]) parameter. The effective size of a population is the number of breeding individuals in a conceptual, ideal population that would evolve by genetic drift at the same rate as the real population being studied. How a population responds to mutation, selection, and gene flow depends on N[subscript e], rather than the actual census population size (N). In most natural populations, N[subscript e] is considerably smaller than N. For these reasons, N[subscript e] is a fundamental parameter in basic population genetics theory as well as in applied conservation genetics. The degree of neutral genetic similarity between populations is highly dependent upon gene flow. When gene flow between a pair of populations is low, the populations are likely to become genetically differentiated. Conversely, when gene flow between populations is high, the populations will tend to be more genetically similar. Amphibians are good model organisms for studying genetic drift and gene flow because they tend to exhibit strong population structure at small spatial scales. This is a consequence of their generally small population sizes, natal philopatry, limited dispersal capabilities, and restricted habitat requirements. They are expected to have easily-detectable signatures of spatial genetic structure and genetic drift. Amphibians can be used as models to further our understanding of evolutionary processes and that understanding can be applied to the conservation of amphibians. Equipped with knowledge of what naturally influences genetic drift and gene flow in amphibians, we can apply the principles of population genetics to mitigate the genetic consequences of amphibian declines. In Chapters 2 and 3, I used molecular genetic data from frog populations to investigate N[subscript e] and the related parameter N[subscript b] (the effective number of breeders). Chapter 2 is a study of a single population of the Oregon spotted frog (Rana pretiosa). My aim was to determine where in the life cycle of this species the greatest reduction in N[subscript b] occurs. I used genetic data from microsatellites to estimate N[subscript b] at two different life stages, eggs and metamorphs, and found that estimates of N[subscript b] were similar at both stages. This result suggests that inflated variance in family size due to egg mass mortality is not a primary cause of N[subscript e] reductions relative to N in this species. Chapter 3 is a comparison of N[subscript e] estimates within and among four species of frogs in the family Ranidae: R. pretiosa, R. luteiventris, R. cascadae, and Lithobates pipiens. I obtained N[subscript e] estimates for 90 populations across the four species, using microsatellite data and several different estimators. The first three species and the western populations of L. pipiens have very small effective sizes (< 50). Eastern populations of L. pipiens are much larger, with N[subscript e] estimates in the hundreds and thousands. I also found significant correlations between N[subscript e] estimates and latitude, longitude, or altitude in R. luteiventris and L. pipiens. Chapter 4 is a study of gene flow among populations of the Cascades frog (Rana cascadae) in the Olympic Mountains of Washington. I quantified genetic differentiation among 22 R. cascadae populations with data from microsatellite markers and used a landscape genetics approach to identify environmental features that have strong influences on gene flow in this species. I used a Random Forests statistical procedure to assess which of several structural connectivity models and 15 landscape variables explained the most variation in genetic distances among populations. I found that the best-fitting Random Forests models were based on different structural connectivity models for two datasets: 'within' and 'between' genetic clusters of populations. The landscape variables identified as the most important also differed across the two datasets, suggesting that landscape influences vary across spatial scales. The results presented in this dissertation led to an increased understanding of effective population size in ranid frogs and of the environmental factors that influence population structure in R. cascadae. These studies provide a foundation for further research on the specific factors that influence genetic drift and gene flow in these species

Tests of gauge boson couplings in polarized e−γe^-\gamma collisions

Single $W$-boson production in $e^-\gamma$ collisions with polarized beams is investigated. Helicity amplitudes for general couplings are derived and their properties are discussed. The results are applied to the Standard Model (SM) and the left-right model. In the framework of SM the updated estimates of the measurement precision of photon anomalous coupling parameters $\kappa,$ $\lambda$ at the NLC with $\sqrt{s_{ ee }}=500$GeV are obtained. The production of right-handed gauge bosons $W^-_{ 2 }$ in these collisions is also analysed.Comment: 18 pages, latex, 7 figures appended as compressed uuencoded .ps fil

Technology and Advanced Development for a Non-Toxic Orbital Maneuvering System and Reaction Control System for Orbiter Upgrade

NASA intends to pursue technology applications to upgrade the Space Shuttle Orbiter OMS and RCS systems with non-toxic propellants. The primary objectives of an upgraded OMS/RCS are improved safety and reliability, reduced operations and maintenance costs while meeting basic OMS/RCS operational and performance requirements. The OMS/RCS has a high degree of direct interaction with the crew and requires subsystem and components that are compatible with integration into the orbiter vehicle with regard to external mold-line, power and thermal control The non-toxic propulsion technology is also applicable to future Human Exploration and Development of Space (HEDS) missions. The HEDS missions have similar requirements for attitude control and lander descent/ascent propulsion and which will emphasize the use of In-Situ Resource for propellants. When used as a regenerative coolant as in the Shuttle Orbiter OMS combustion chamber, non-toxic fuels such as ethanol are limited in their cooling capacity by the bulk temperature rise permitted to prevent film boiling or possible coking. Typical regeneratively cooled chambers are constructed from highly conductive copper, which maximizes heat transfer, or from low conductivity materials like stainless steel that can also exacerbate cooling problems. For an ethanol cooled application the heat transfer into the fluid must be controlled to reduce the fuel coolant bulk temperature rise. An approach to provide this control is the subject of this report. This report is being issued to document work done by Aerojet on NASA contract NAS 8-98042. Specifically, this project investigates of the use of ethanol, a designated non-toxic fuel, as a coolant for the Space Shuttle Orbital Maneuvering System Engine combustion chamber. The project also addresses a cost reducing fabrication technique for construction of such a combustion chamber. The study contained three major sub-tasks: an analytical investigation and trade study which included layout of a flight type chamber concept, the fabrication and evaluation of formed platelet liner panels and the preparation and testing of mechanical properties specimens representative of a novel hot gas wall concept

Ecological strategies predict associations between aquatic and genetic connectivity for dryland amphibians

The study of how population genetic structure is shaped by attributes of the environment is a central scientific pursuit in ecology and conservation. But limited resources may prohibit landscape genetics studies for many threatened species, particularly given the pace of current environmental change. Understanding the extent to which species' ecological strategies-their life histories, biology, and behavior-predict patterns and drivers of population connectivity is a critical step in evaluating the potential of multi-taxa inference in landscape genetics. We present results of a landscape genetic study of three dryland amphibians: the canyon treefrog (Hyla arenicolor), red-spotted toad (Anaxyrus punctatus), and Mexican spadefoot (Spea multiplicata). These species characterize a range of ecological strategies, driven primarily by different water dependencies, enabling amphibian survival in arid and semiarid environments. We examined a suite of hypothesized relationships between genetic connectivity and landscape connectivity across species. We found a positive relationship between population differentiation and water dependency, e.g., longer larval development periods and site fidelity for reliable water sources. We also found that aquatic connectivity is important for all species, particularly when considered with topography (slope). The effect of spatial scale varied by species, with canyon treefrogs and Mexican spadefoots characterized by relatively consistent results at different scales in contrast to the stark differences in results for red-spotted toads at different scales. Using ecological information to predict relationships between genetic and landscape connectivity is a promising approach for multi-taxa inference and may help inform conservation efforts where single-species genetic studies are not possible.This is the publisher’s final pdf. The published article is copyrighted by Ecological Society of America and can be found at: http://www.esajournals.org/loi/ecolKeywords: landscape genetics, traits, red-spotted toad (Anaxyrus punctatus), canyon treefrog (Hyla arenicolor), life histories, Mexican spadefoot (Spea multiplicata), dryland ecology, anuransKeywords: landscape genetics, traits, red-spotted toad (Anaxyrus punctatus), canyon treefrog (Hyla arenicolor), life histories, Mexican spadefoot (Spea multiplicata), dryland ecology, anuran

Dispersal strength determines meta-community structure in a dendritic riverine network

AIM: Meta-community structure is a function of both local (site-specific) and regional (landscape-level) ecological factors, and the relative importance of each may be mediated by the dispersal ability of organisms. Here, we used aquatic invertebrate communities to investigate the relationship between local and regional factors in explaining distance decay relationships (DDRs) in fragmented dendritic stream networks. LOCATION: Dryland streams distributed within a 400 km2 section of the San Pedro River basin, southeastern Arizona, USA. METHODS: We combined fine-scale local information (flow and habitat characteristics) with regional-scale information to explain DDR patterns in community composition of aquatic invertebrate species with a wide range of dispersal abilities. We used a novel application of a landscape resistance modeling approach (originally developed for landscape genetic studies) that simultaneously assessed the importance of local and regional ecological factors as well as dispersal ability of organisms. RESULTS: We found evidence that both local and regional factors influenced aquatic invertebrate DDRs in dryland stream networks, and the importance of each factor depended on the dispersal capacities of the organisms. Local and weak dispersers were more affected by site-specific factors, intermediate dispersers by landscape-level factors, and strong dispersers showed no discernable pattern. This resulted in a strongly hump-shaped relationship between dispersal ability and landscape-level factors, where only moderate dispersers showed evidence of DDRs. Unlike most other studies of dendritic networks, our results suggest that overland pathways, using perennial refugia as stepping-stones, might be the main dispersal route in fragmented stream networks. MAIN CONCLUSIONS: We suggest that using a combination of landscape and local distance measures can help to unravel meta-community patterns in dendritic systems. Our findings have important conservation implications, such as the need to manage river systems for organisms that span a wide variety of dispersal abilities and local ecological requirements. Our results also highlight the need to preserve perennial refugia in fragmented networks, since they may ensure the viability of aquatic meta-communities by facilitating dispersal.Keywords: landscape resistance, aquatic invertebrates, connectivity, dendritic networks, dispersal, distance decay relationship, drought, meta-community, ArizonaKeywords: landscape resistance, aquatic invertebrates, connectivity, dendritic networks, dispersal, distance decay relationship, drought, meta-community, Arizon

Reliable effective number of breeders/adult census size ratios in seasonal-breeding species: Opportunity for integrative demographic inferences based on capture-mark-recapture data and multilocus genotypes

The ratio of the effective number of breeders (Nb) to the adult census size (Na), Nb/Na, approximates the departure from the standard capacity of a population to maintain genetic diversity in one reproductive season. This information is relevant for assessing population status, understanding evolutionary processes operating at local scales, and unraveling how life-history traits affect these processes. However, our knowledge on Nb/Na ratios in nature is limited because estimation of both parameters is challenging. The sibship frequency (SF) method is adequate for reliable Nb estimation because it is based on sibship and parentage reconstruction from genetic marker data, thereby providing demographic inferences that can be compared with field-based information. In addition, capture–mark–recapture (CMR) robust design methods are well suited for Na estimation in seasonal-breeding species. We used tadpole genotypes of three pond-breeding amphibian species (Epidalea calamita, Hyla molleri, and Pelophylax perezi, n = 73–96 single-cohort tadpoles/species genotyped at 15–17 microsatellite loci) and candidate parental genotypes (n = 94–300 adults/species) to estimate Nb by the SF method. To assess the reliability of Nb estimates, we compared sibship and parentage inferences with field-based information and checked for the convergence of results in replicated subsampled analyses. Finally, we used CMR data from a 6-year monitoring program to estimate annual Na in the three species and calculate the Nb/Na ratio. Reliable ratios were obtained for E. calamita (Nb/Na = 0.18–0.28) and P. perezi (0.5), but in H. molleri, Na could not be estimated and genetic information proved insufficient for reliable Nb estimation. Integrative demographic studies taking full advantage of SF and CMR methods can provide accurate estimates of the Nb/Na ratio in seasonal-breeding species. Importantly, the SF method provides results that can be readily evaluated for reliability. This represents a good opportunity for obtaining robust demographic inferences with wide applications for evolutionary and conservation research

A Comparative Analysis of Competency Frameworks for Youth Workers in the Out-of-School Time Field

Research suggests that the quality of out-of-school time (OST) programs is related to positive youth outcomes and skilled staff are a critical component of high quality programming. This descriptive case study of competency frameworks for youth workers in the OST field demonstrates how experts and practitioners characterize a skilled youth worker. A comparative analysis of 11 competency frameworks is conducted to identify a set of common core competencies. A set of 12 competency areas that are shared by existing frameworks used in the OST field are identified. The age of youth being served, descriptions of mastery for each competency area, an emphasis on developing mid-level managers, and incorporating research emerge as factors that should be addressed in future competency frameworks