975 resultados para European immigrant population


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Thesis (Master's)--University of Washington, 2016-06

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While the feasibility of bottleneck-induced speciation is in doubt, population bottlenecks may still affect the speciation process by interacting with divergent selection. To explore this possibility, I conducted a laboratory speciation experiment using Drosophila pseudoobscura involving 78 replicate populations assigned in a two-way factorial design to both bottleneck (present vs. absent) and environment (ancestral vs. novel) treatments. Populations independently evolved under these treatments and were then tested for assortative mating and male mating success against their common ancestor. Bottlenecks alone did not generate any premating isolation, despite an experimental design that was conducive to bottleneck-induced speciation. Premating isolation also did not evolve in the novel environment treatment, neither in the presence nor absence of bottlenecks. However, male mating success was significantly reduced in the novel environment treatment, both as a plastic response to this environment and as a result of environment-dependent inbreeding effects in the bottlenecked populations. Reduced mating success of derived males will hamper speciation by enhancing the mating success of immigrant, ancestral males. Novel environments are generally thought to promote ecological speciation by generating divergent natural selection. In the current experiment, however, the novel environment did not cause the evolution of any premating isolation and it reduced the likelihood of speciation through its effects on male mating success.

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A simulation-based modelling approach is used to examine the effects of stratified seed dispersal (representing the distribution of the majority of dispersal around the maternal parent and also rare long-distance dispersal) on the genetic structure of maternally inherited genomes and the colonization rate of expanding plant populations. The model is parameterized to approximate postglacial oak colonization in the UK, but is relevant to plant populations that exhibit stratified seed dispersal. The modelling approach considers the colonization of individual plants over a large area (three 500 km x 10 km rolled transects are used to approximate a 500 km x 300 km area). Our approach shows how the interaction of plant population dynamics with stratified dispersal can result in a spatially patchy haplotype structure. We show that while both colonization speeds and the resulting genetic structure are influenced by the characteristics of the dispersal kernel, they are robust to changes in the periodicity of long-distance events, provided the average number of long-distance dispersal events remains constant. We also consider the effects of additional physical and environmental mechanisms on plant colonization. Results show significant changes in genetic structure when the initial colonization of different haplotypes is staggered over time and when a barrier to colonization is introduced. Environmental influences on survivorship and fecundity affect both the genetic structure and the speed of colonization. The importance of these mechanisms in relation to the postglacial spread and genetic structure of oak in the UK is discussed.

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The genome of the European hedgehog, Erinaceus concolor and E. europaeus, shows a strong signal of cycles of restriction to glacial refugia and postglacial expansion. Patterns of expansion, however, differ for mitochondrial DNA (mtDNA) and preliminary analysis of nuclear markers. In this study, we determine phylogeographic patterns in the hedgehog using two loci of the major histocompatibility complex (MHC), isolated for the first time in hedgehogs. These genes show long persistence times and high polymorphism in many species because of the actions of balancing selection. Among 84 individuals screened for variation, only two DQA alleles were identified in each species, but 10 DQB alleles were found in E. concolor and six in E. europaeus. A strong effect of demography on patterns of DQB variability is observed, with only weak evidence of balancing selection. While data from mtDNA clearly subdivide both species into monophyletic subgroups, the MHC data delineate only E. concolor into distinct subgroups, supporting the preliminary findings of other nuclear markers. Together with differences in variability, this suggests that the refugia history and/or expansion patterns of E. concolor and E. europaeus differ.

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We report the clinical characteristics of a schizophrenia sample of 409 pedigrees-263 of European ancestry ( EA) and 146 of African American ancestry ( AA)-together with the results of a genome scan ( with a simple tandem repeat polymorphism interval of 9 cM) and follow-up fine mapping. A family was required to have a proband with schizophrenia ( SZ) and one or more siblings of the proband with SZ or schizoaffective disorder. Linkage analyses included 403 independent full-sibling affected sibling pairs ( ASPs) ( 279 EA and 124 AA) and 100 all-possible half-sibling ASPs ( 15 EA and 85 AA). Nonparametric multipoint linkage analysis of all families detected two regions with suggestive evidence of linkage at 8p23.3-q12 and 11p11.2-q22.3 ( empirical Z likelihood-ratio score [ Z(lr)] threshold >= 2.65) and, in exploratory analyses, two other regions at 4p16.1-p15.32 in AA families and at 5p14.3-q11.2 in EA families. The most significant linkage peak was in chromosome 8p; its signal was mainly driven by the EA families. Z(lr) scores >= 2.0 in 8p were observed from 30.7 cM to 61.7 cM ( Center for Inherited Disease Research map locations). The maximum evidence in the full sample was a multipoint Z(lr) of 3.25 ( equivalent Kong-Cox LOD of 2.30) near D8S1771 ( at 52 cM); there appeared to be two peaks, both telomeric to neuregulin 1 ( NRG1). There is a paracentric inversion common in EA individuals within this region, the effect of which on the linkage evidence remains unknown in this and in other previously analyzed samples. Fine mapping of 8p did not significantly alter the significance or length of the peak. We also performed fine mapping of 4p16.3-p15.2, 5p15.2-q13.3, 10p15.3-p14, 10q25.3-q26.3, and 11p13-q23.3. The highest increase in Z(lr) scores was observed for 5p14.1-q12.1, where the maximum Z(lr) increased from 2.77 initially to 3.80 after fine mapping in the EA families.

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As part of a longitudinal study of the epidemiology of rabbit haemorrhagic disease virus (RHDV) in New Zealand, serum samples were obtained from trapped feral animals that may have consumed European rabbit (Oryctolagus cuniculus) carcasses (non-target species). During a 21-month period when RHDV infection was monitored in a defined wild rabbit population, 16 feral house cats (Felis catus), 11 stoats (Mustela erminea), four ferrets (Mustela furo) and 126 hedgehogs (Erinaceus europaeus) were incidentally captured in the rabbit traps. The proportions of samples that were seropositive to RHDV were 38% for cats, 18% for stoats, 25% for ferrets and 4% for hedgehogs. Seropositive non-target species were trapped in April 2000, in the absence of an overt epidemic of rabbit haemorrhagic disease (RHD) in the rabbit population, but evidence of recent infection in rabbits was shown. Seropositive non-target species were found up to 2.5 months before and 1 month after this RHDV activity in wild rabbits was detected. Seropositive predators were also trapped on the site between 1 and 4.5 months after a dramatic RHD epidemic in February 2001. This study has shown that high antibody titres can be found in non-target species when there is no overt evidence of RHDV infection in the rabbit population, although a temporal relationship could not be assessed statistically owning to the small sample sizes. Predators and scavengers might be able to contribute to localised spread of RHDV through their movements.

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A longitudinal capture-mark-recapture study was conducted to determine the temporal dynamics of rabbit haemorrhagic disease (RHD) in a European rabbit (Oryctolagus cuniculus) population of low to moderate density on sand-hill country in the lower North Island of New Zealand. A combination of sampling ( trapping and radio-tracking) and diagnostic (cELISA, PCR and isotype ELISA) methods was employed to obtain data weekly from May 1998 until June 2001. Although rabbit haemorrhagic disease virus ( RHDV) infection was detected in the study population in all 3 years, disease epidemics were evident only in the late summer or autumn months in 1999 and 2001. Overall, 20% of 385 samples obtained from adult animals older than 11 weeks were seropositive. An RHD outbreak in 1999 contributed to an estimated population decline of 26%. A second RHD epidemic in February 2001 was associated with a population decline of 52% over the subsequent month. Following the outbreaks, the seroprevalence in adult survivors was between 40% and 50%. During 2000, no deaths from RHDV were confirmed and mortalities were predominantly attributed to predation. Influx of seronegative immigrants was greatest in the 1999 and 2001 breeding seasons, and preceded the RHD epidemics in those years. Our data suggest that RHD epidemics require the population immunity level to fall below a threshold where propagation of infection can be maintained through the population.

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Cadmium has been widely used in various industries for the past fifty years, with current world production standing at around 16,755 tonnes per year. Very little cadmium is ever recycled and the ultimate fate of all cadmium is the environment. In view of reports that cadmium in the environment is increasing, this thesis aims to identify population groups 'at risk' of receiving dietary intakes of cadmium up to or above the current Food and Agricultural Organisation/World Health Organisation maximum tolerable intake of 70 ug/day. The study involves the investigation of one hundred households (260 individuals) who grow a large proportion of their vegetable diet in garden soils in the Borough of Walsall, part of an urban/industrial area in the United Kingdom. Measurements were made of the cadmium levels in atmospheric deposition, soil, house dust, diet and urine from the participants. Atmospheric deposition of cadmium was found to be comparable with other urban/industrial areas in the European Community, with deposition rates as high as 209 g ha-1 yr-1. The garden soils of the study households were found to contain up to 33 mg kg-1 total cadmium, eleven times the highest level usually found in agricultural soils. Dietary intakes of cadmium by the residents from food were calculated to be as high as 68 ug/day. It is suggested that with intakes from other sources, such as air, adventitious ingestion, smoking and occupational exposure, total intakes of cadmium may reach or exceed the FAO/WHO limit. Urinary excretion of cadmium amongst a non-smoking, non-occupationally exposed sub-group of the study population was found to be significantly higher than that of a similar urban population who did not rely on home-produced vegetables. The results from this research indicate that present levels of cadmium in urban/industrial areas can increase dietary intakes and body burdens of cadmium. As cadmium serves no useful biological function and has been found to be highly toxic, it is recommended that policy measures to reduce human exposure on the European scale be considered.

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The induced lenses in the Yb:YAG rods and disks end-pumped by a Gaussian beam were analyzed both analytically and numerically. The thermally assisted mechanisms of the lens formation were considered to include: the conventional volume thermal index changes ("dn/dT"), the bulging of end faces, the photoelastic effect, and the bending (for a disk). The heat conduction equations (with an axial heat flux for a disk and a radial heat flux for a rod), and quasi-static thermoelastic equations (in the plane-stress approximation with free boundary conditions) were solved to find the thermal lens power. The population rate equation with saturation (by amplified spontaneous emission or an external wave) was examined to find the electronic lens power in the active elements.

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BACKGROUND/AIMS: Alcohol-related problems are relevant in the elderly, particularly in developed countries, but there is a lack of cross-country comparisons. The present work aims to examine the frequency and patterns of alcohol consumption in older adults across different European countries, and to analyze the relationship between socioeconomic status and gender with alcohol consumption. METHODS: General population-based household surveys of randomly selected adults over 60 years of age in 14 European countries. PARTICIPANTS: 10,119 subjects [mean age: 70.4 (SD = 7.1)], 61.9% women. RESULTS: There are marked differences in alcohol consumption across countries. Except for three countries from eastern regions, most people in all countries present moderate consumption regarding the amount of alcohol and pattern of use. However, there are marked gender differences, with a higher intake in men (effect sizes ranging from 0.57 to 1.27), although these differences are relatively proportional across countries. Finally, a higher socioeconomic status is positively related (B = 0.845, 95% CI: 0.30/1.40) with alcohol consumption after controlling for gender, age, health-functioning status and the country's development level. CONCLUSIONS: There are marked differences in consumption of alcohol in the elderly between the different countries, and male gender, as well as a higher SES, were associated with higher alcohol consumption.

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This study deals with the question of how German members of the European Parliament (MEPs) represent the German model of religion–state relations at the European level. Based on a survey and interviews with German MEPs as well as a content-analysis of German MEPs’ speeches, motions and parliamentary questions during the seventh term of the European Parliament (EP), our study demonstrates that this model is represented in three dimensions. First, German MEPs reflect the close cooperation between the churches and the state in Germany, primarily on social issues, through largely church- and religion-friendly attitudes and relatively frequent contacts with religious interest-groups. Second, by referring to religious freedoms and minorities primarily outside the EU and by placing Islam in considerably more critical contexts than Christianity, German MEPs create a cultural demarcation line between Islam and Christianity through their parliamentary activities, which is similar to, though less politicised than, cultural boundaries often produced in public debates in Germany. Third, our study illustrates similar patterns of religious affiliation and subjective religiosity among German parliamentarians in both the EP and the national Parliament, which to some degree also reflect societal trends in Germany. Yet our data also suggest that European political elites are more religious than the average German population. If the presence of religion in terms of religious interest-groups and arguments is included, the EP appears to be more secularist than the German Parliament.