Effects Of Geographic Region Research Articles

Modelling with uncertainty: Introducing a probabilistic framework to predict animal population dynamics

Predictive population models designed to assist managers and policy makers require an explicit treatment of inherent uncertainty and variability. These are particular concerns when modelling non-native and reintroduced species, when data have been collected within one geographical or ecological context but predictions are required for another, or when extending models to predict the consequences of environmental change (e.g., climate or land-use). We present an aspatial, probabilistic framework of hierarchical process models for predicting population growth even when data are sparse or of poor quality. Insight into the factors affecting population dynamics in real landscapes can be provided and Kullback–Leibler distances are used to compare the relative output of models. This flexible yet robust framework gives easily interpretable results, allowing managers as well as modellers to invalidate anomalous models and apply others to real-life scenarios. We illustrate the framework’s power with a meta-analysis of European wild boar ( Sus scrofa) data. We test hypotheses about the effect of geographic region, hunting and mast years on wild boar population growth, to build models of wild boar dynamics for the UK. The framework quantifies the importance of hunting pressure as a driver of population growth, and confirms that reproductive success is greatly decreased in poor mast years, suggesting that the key to predicting wild boar dynamics is to ascertain local hunting pressure and to better understand changing food availability. Geography had no significant effect, indicating that it is not a good proxy for modelling the impact of change in climate or land-use on wild boar populations at the European scale. We use the framework to predict population abundance 9 years after an isolated population of wild boar established in the UK; in a comparison with the only field data and two independent modelling exercises, our framework provides the most robust and informative results.

Prevalence of coccidia parasites (Protozoa) in red squirrels (Sciurus vulgaris): effects of host phenotype and environmental factors.

We investigated the relative importance of environmental factors versus host phenotype in determining parasite prevalence in Eurasian red squirrels (Sciurus vulgaris). One hundred and forty-three fecal samples of 116 different squirrels collected in 2000 and 2001 from five study areas in the Italian Alps, were examined for intestinal protozoans. Two species of Eimeria were present with a medium to high prevalence in both years and in all areas, while two other species were rare, occurring only in some areas and not in all years. Cryptosporidium parvum had a high prevalence in the two study areas of the Western Alps, while in the three areas of the Central Alps it was recorded only once. The prevalence of Eimeria sciurorum and C. parvum fluctuated in parallel with squirrel density, suggesting a possible correlation between the presence of these protozoans and host density. A gender effect on E. sciurorum prevalence at low density could be explained by different space use patterns and social organization of males and females. C. parvum occurred more frequently in young squirrels, suggesting an acquired immunity in adults, but age-related susceptibility was not found for eimerian species. The coccidian community was more similar within than between regions, and study area and year were key parameters in predicting coccidia infection. There was no evidence of competition between coccidian species, but one positive interaction between E. sciurorum and E. andrewsi was observed. Our results suggest that the effects of geographic region, area features, and year effects probably related to fluctuations in host population density, were more important than individual phenotypic host characteristics in structuring the coccidian assemblage and determining levels of parasite prevalence in red squirrel populations.

Geographical variation in disease progression in HIV-1 seroconverted injecting drug users in Europe?

Human immunodeficiency virus (HIV) disease progression might vary by geographical region due to differences in the spectrum of HIV-related illnesses and (access to) health care. Therefore, the effect of geographical region, next to the effect of other potential cofactors, on disease progression in 664 injecting drug users (IDU) with documented HIV seroconversion from eight cohorts in Europe was studied. Kaplan-Meier methods and Cox proportional hazards analysis were performed to assess the effect of geographical region, other sociodemographics, drug use and repeated HIV exposure on progression from HIV seroconversion to immunosuppression, AIDS and death with AIDS. We considered the confounding effect of study-design related factors (e.g. setting of follow-up), and accounted for pre-AIDS death from natural causes by imputing when each endpoint would have occurred, had they not died without AIDS. Estimates of progression to AIDS and death with AIDS were substantially faster after taking pre-AIDS mortality into account. Median incubation time from seroconversion to the first CD4 count < 200 cells/microliter was 7.7 years (95% CI: 7.1-8.3) and to AIDS 10.4 years (95% CI: 9.8-infinity). The 10-year survival was 70.3% (95% CI: 62.8-76.6). The relative hazards (RH) of AIDS for IDU from central and southern Europe compared with IDU from northern Europe was 1.9 (95% CI: 1.2-3.0) and 1.2 (95% CI: 0.6-2.3), respectively, before, and 1.5 (95% CI: 0.7-3.2) and 1.1 (95% CI: 0.6-2.3) after taking differences in study-design related factors into account. Accounting for these factors, the RH of death with AIDS was 0.9 (95% CI: 0.3-2.5) for central and 1.2 (95% CI: 0.4-3.4) for southern Europe compared with northern Europe. For the first CD4 count < 200 cells/microliter these figures were 0.8 (95% CI: 0.5-1.4) and 0.8 (95% CI: 0.5-1.4). Age at seroconversion was the strongest predictor of disease progression. No statistically significant differences in disease progression were found by gender, foreign nationality, drug use and potential repeated HIV exposure. We found no evidence for regional variability in HIV disease progression among European IDU. Future studies evaluating geographical differences should consider the confounding effect of study-design related factors and differential non-AIDS mortality. As age is an important determinant of disease progression, it should be considered in recommending treatment.

Alien plants in Czech village flora: An analysis of species numbers

AbstractFlora of 42 villages located at the territory of the Czech Republic between 12–16 °E and 49–51 °N was analysed to (1) quantify the proportion of archaeophytes (i.e. aliens introduced before 1500), neophytes (aliens introduced after that date) and native species, and (2) assess the factors affecting the representation of these particular groups. Alien species constitute on average about one third of the species present in the flora of a Czech village, archaeophytes contributing 17.8% (32.3 species), neophytes 14.4% (26.8 species). Number and proportion of archaeophytes increased with village size and decreased with its altitude, native species were correlated with neither factor. Village size, expressed as the number of houses, and the distance from a middle‐sized town were the significant predictors explaining nearly 50% of variation in number of neophytes. There was also an effect of geographical region in which a village was located on the representation of neophytes. Neither the richness nor the proportion of neophytes in village floras were correlated with the distance from a small town or that from railway, nearest river and main road.

An Application of Commercial Panel Data for Public Policy Research: Estimates of Tip Earnings1

Unique panel data provided by NPD Research, Inc., were used to investigate the magnitude and interactive effects upon tipping aggregates and levels. The analysis revealed that tips by American households aggregate to $6.2, $6.3, and $6.7 billion annually in restaurants and other eating places in 1982, 1983, and 1984 respectively. The information was collected by means of diaries kept by the tippers themselves, which was regarded as a more accurate source than inquiries of either the tip recipients or their employers. The paper covers the relationship between the characteristics of the tippers and of the tipping occasions and the propensity and magnitude of tipping. One finding of the regression analysis is that there are sizable differences in tip rates across tipping type restaur­ ant categories when the combined effects of geographic region, metropolitan size, and restaurant options such as acceptance of credit cards and reservations and service of alcoholic beverages are considered.

Selected Indexes of the Academic and Professional Preparation of Music Supervisors in Canada

The purpose of this baseline study was to describe indexes of the academic and professional preparation of music supervisors in Canada, with particular emphasis given to the effects of geographic region in Canada, music supervisor type, and jurisdiction size type on these indexes. The study constitutes a first step toward the generation of a theoretical model and subsequently, of a competency-based model of the academic and professional preparation of music supervisors. The study is based on descriptive data derived from a national questionnaire survey of music supervisors in Canada.