Geographical Regions (geographical + regions)

Distribution by Scientific Domains
Distribution within Life Sciences

Kinds of Geographical Regions

  • different geographical regions
  • other geographical regions


  • Selected Abstracts


    Corporate social and environmental responsibility in Asian countries and other geographical regions

    CORPORATE SOCIAL RESPONSIBILITY AND ENVIRONMENTAL MANAGEMENT, Issue 4 2007
    C. Christopher Baughn
    Abstract This study examines two aspects of corporate social responsibility (social and environmental CSR) in 15 Asian countries. The performance of firms in these Asian countries on the two types of CSR is also assessed relative to country economic, political and social conditions, and compared with those of other regions (Western Europe, East/Central Europe, Australia/New Zealand, US/Canada, Middle East and Africa). Drawing from over 8700 surveys of firms in 104 countries, this study demonstrates substantial country and regional differences in CSR. Firms are embedded in different country contexts, with differing underlying institutional capacities. Strong revealed relationships between CSR and country economic, political and social contexts reflect the importance of a country's development of such institutional capacity to promote and support CSR practices. Copyright © 2007 John Wiley & Sons, Ltd and ERP Environment. [source]


    The transferability of distribution models across regions: an amphibian case study

    DIVERSITY AND DISTRIBUTIONS, Issue 3 2009
    Flavio Zanini
    ABSTRACT Aim, Predicting species distribution is of fundamental importance for ecology and conservation. However, distribution models are usually established for only one region and it is unknown whether they can be transferred to other geographical regions. We studied the distribution of six amphibian species in five regions to address the question of whether the effect of landscape variables varied among regions. We analysed the effect of 10 variables extracted in six concentric buffers (from 100 m to 3 km) describing landscape composition around breeding ponds at different spatial scales. We used data on the occurrence of amphibian species in a total of 655 breeding ponds. We accounted for proximity to neighbouring populations by including a connectivity index to our models. We used logistic regression and information-theoretic model selection to evaluate candidate models for each species. Location, Switzerland. Results, The explained deviance of each species' best models varied between 5% and 32%. Models that included interactions between a region and a landscape variable were always included in the most parsimonious models. For all species, models including region-by-landscape interactions had similar support (Akaike weights) as models that did not include interaction terms. The spatial scale at which landscape variables affected species distribution varied from 100 m to 1000 m, which was in agreement with several recent studies suggesting that land use far away from the ponds can affect pond occupancy. Main conclusions, Different species are affected by different landscape variables at different spatial scales and these effects may vary geographically, resulting in a generally low transferability of distribution models across regions. We also found that connectivity seems generally more important than landscape variables. This suggests that metapopulation processes may play a more important role in species distribution than habitat characteristics. [source]


    Present and potential distribution of invasive garlic mustard (Alliaria petiolata) in North America

    DIVERSITY AND DISTRIBUTIONS, Issue 4 2002
    Erik Welk
    Abstract. This paper demonstrates the use of a bioclimatic model mapped over geographical regions as a tool for spatially refined risk assessment for the establishment of non-indigenous plants with invasive behaviour. Drawing on the relationship between plant distribution and climate, the approach uses gridded spatial interpolated monthly means of temperature and precipitation linked with accurate maps of general native distribution ranges to predict the long-term potential of a plant species to invade a certain region. The ascertained potential for establishment is illustrated by the example of garlic mustard (Alliaria petiolata[M. Bieb.] Cavara & Grande) in North America. The first step is to calculate and visualize the number of populated grid cells along climatic gradients in frequency diagrams for the general native distribution range. Interpretations of the response curves recorded are used for assessing apparent climatic range boundaries. Modelling was gradually optimized based on the results of experience-based interpretations and by examining omission and over-representation errors. The obtained climatic model of the range of A. petiolata shows considerable congruencies with its mapped, native Eurasian range. Degrees of climatic similarity between North America and the native range of A. petiolata were calculated with the help of GIS methodology and were used to assess the regionally different likelihood of establishment in North America of the invasive species under consideration. [source]


    Phytogeographical evidence for post-glacial dispersal limitation of European beech forest species

    ECOGRAPHY, Issue 6 2009
    Wolfgang Willner
    The post-glacial migration of European beech Fagus sylvatica has been addressed by many studies using either genetic or fossil data or a combination of both. In contrast to this, only little is known about the migration history of beech forest understorey species. In a review of phytosociological literature, we identified 110 plant species which are closely associated with beech forest. We divided the distribution range of European beech forests into 40 geographical regions, and the presence or absence of each species was recorded for each region. We compared overall species numbers per region and numbers of narrow-range species (species present in <10 regions). A multiple regression model was used to test for the explanatory value of three potential diversity controls: range in elevation, soil type diversity, and distance to the nearest potential refuge area. A hierarchical cluster analysis of the narrow-range species was performed. The frequency of range sizes shows a U-shaped distribution, with 42 species occurring in <10 regions. The highest number of beech forest species is found in the southern Alps and adjacent regions, and species numbers decrease with increasing distance from these regions. With only narrow-range species taken into consideration, secondary maxima are found in Spain, the southern Apennines, the Carpathians, and Greece. Distance to the nearest potential refuge area is the strongest predictor of beech forest species richness, while altitudinal range and soil type diversity had little or no predictive value. The clusters of narrow-range species are in good concordance with the glacial refuge areas of beech and other temperate tree species as estimated in recent studies. These findings support the hypothesis that the distribution of many beech forest species is limited by post-glacial dispersal rather than by their environmental requirements. [source]


    Adaptive advantages of myrmecochory: the predator-avoidance hypothesis tested over a wide geographic range

    ECOGRAPHY, Issue 5 2005
    Antonio J. Manzaneda
    The predator-avoidance hypothesis states that once released from the parent plant, myrmecochorous seeds are rapidly taken by ants to their nests, where they are protected from predators. Previous studies conducted to test this hypothesis have frequently neglected two major aspects necessary for its verification: 1) the influence of processes acting after the seed release and 2) the spatial evenness of such processes. Thus, large-scale variations in the mechanisms acting beyond seed release, and possibly influencing seed escape from predators, remain poorly documented. Here, we present the results of a post-dispersal seed-removal experiment on the myrmecochorous herb Helleborus foetidus, aimed at verifing the predator-avoidance hypothesis by considering two key post-release aspects of seed fate: seed destination (dispersed or nondispersed) and seed burial (buried or not buried). Experiments were performed in four different regions in the Iberian Peninsula. After three days of exposure of seeds to the main predator (fieldmice Apodemus sylvaticus), ca 30% of the seeds were removed. Seed destination affected the proportion of seeds escaping predation, but the sign, magnitude and statistical significance of the effect varied among the geographical regions. In the southern region (Cazorla), seeds dispersed in ant nests or intermediate destinations suffered scarcely any predation, but seeds under reproductive-age plants experienced losses ca 50%. Conversely, in the northern region (Caurel), seeds in nests suffered significantly greater losses than seeds under plants or intermediate destinations, suggesting that nests were especially unsafe destinations. Seed burial had a strong impact on seed escape from predators, and its effect was highly consistent among geographical regions. In view of the consistency of its effect at different spatial scales, seed burial was a more general mechanism for predation avoidance than seed relocation to ant nests, which was habitat- and/or ant-species-dependent. Our results thus only partially support the predator-avoidance hypothesis for the evolution of myrmecochory. [source]


    The implications of different species concepts for describing biodiversity patterns and assessing conservation needs for African birds

    ECOGRAPHY, Issue 5 2005
    Shaun Dillon
    It has been suggested that switching from the widely used Biological Species Concept to a Phylogenetic Species Concept, would result in the appearance of hitherto neglected patterns of endemism. The problem has mainly been analyzed with respect to endemic taxa and for rather limited geographical regions, but will here be analysed for the entire resident avifauna of sub-Saharan Africa. A database of African bird distributions was re-edited to create two new datasets representing 1572 biological species and 2098 phylogenetic species. Species richness patterns were virtually identical with the two taxonomies, and only subtle changes were found in the geographical variation in range-size rarity sum. However, there were some differences in the most range-restricted species, with increased complexity of long-recognized centres of endemism. Overall, then, the large-scale biogeographic patterns are robust to changes in species concepts. This reflects the aggregated nature of endemism, with certain areas acting as "species pumps" and large intervening areas being characterised by a predominance of widespread species which distribute themselves in accordance with contemporary environmental conditions. The percentages of phylogenetic and threatened species captured in a BSC near-minimum set of 64 grid-cells and a PSC near-maximum set, with the same number of grid-cells, are very similar. [source]


    Field theory for biogeography: a spatially explicit model for predicting patterns of biodiversity

    ECOLOGY LETTERS, Issue 1 2010
    James P. O'Dwyer
    Abstract Predicting the variation of biodiversity across the surface of the Earth is a fundamental issue in ecology, and in this article we focus on one of the most widely studied spatial biodiversity patterns: the species,area relationship (SAR). The SAR is a central tool in conservation, being used to predict species loss following global climate change, and is striking in its universality throughout different geographical regions and across the tree of life. In this article we draw upon the methods of quantum field theory and the foundation of neutral community ecology to derive the first spatially explicit neutral prediction for the SAR. We find that the SAR has three phases, with a power law increase at intermediate scales, consistent with decades of documented empirical patterns. Our model also provides a building block for incorporating non-neutral biological variation, with the potential to bridge the gap between neutral and niche-based approaches to community assembly. Ecology Letters (2010) 13: 87,95 [source]


    Phenotypic and genotypic characterization of encapsulated Escherichia coli isolated from blooms in two Australian lakes

    ENVIRONMENTAL MICROBIOLOGY, Issue 5 2005
    Michelle L. Power
    Summary Escherichia coli has long been used as an indicator organism for water quality assessment. Recently there has been an accumulation of evidence that suggests some strains of this organism are able to proliferate in the environment, a characteristic that would detract from its utility as an indicator of faecal pollution. Phenotypic and genotypic characterization of E. coli isolated from blooms in two Australian lakes, separated by a distance of approximately 200 km, identified that the blooms were dominated by three E. coli strains. A major phenotypic similarity among the three bloom strains was the presence of a group 1 capsule. Genetic characterization of a conserved region of the cps gene cluster, which encodes group 1 capsules, identified a high degree of genetic variation within the bloom isolates. This differs from previously described encapsulated E. coli strains which are highly conserved at the cps locus. The phenotypic or genotypic profiles of the bloom strains were not identified in 435 E. coli strains isolated from vertebrates. The occurrence of these encapsulated strains suggests that some E. coli have evolved a free-living lifestyle and do not require a host in order to proliferate. The presence of the same three strains in bloom events in different geographical regions of a temperate climate, and at different times, indicates that free-living E. coli strains are able to persist in these water reservoirs. This study provides further evidence of circumstances where caution is required in using E. coli as an indicator organism for water quality. [source]


    A prototype store choice and location modelling system using Dempster,Shafer theory

    EXPERT SYSTEMS, Issue 5 2002
    Malcolm Beynon
    This paper concerns the study of destination choice modelling, more specifically identifying within some area (e.g. a city) the region where a particular store is the most favourable to be visited by individuals. An influence measure is constructed for each individual, which incorporates the modern technique known as Dempster,Shafer theory. Based on the evidence of the shopping destinations of individuals, geographical regions are found for levels of largest belief and plausibility (within Dempster,Shafer theory) for specific stores being the most favourable to visit. Additionally, this method may be used to identify the possible position of new stores, based on regions of most uncertainty or conflict in store choice. A prototype choice modelling system is introduced to enable the series of associated results to be easily visualized and analysed. [source]


    Construction of a multivalent vaccine strain of Shigella flexneri and evaluation of serotype-specific immunity

    FEMS IMMUNOLOGY & MEDICAL MICROBIOLOGY, Issue 3 2006
    Amy V. Jennison
    Abstract Shigella flexneri causes more fatalities by shigellosis than any other Shigella species. There are 13 different serotypes of S. flexneri and their distribution varies between endemic geographical regions. The immune response against S. flexneri is serotype-specific, so current immunization strategies have required the administration of multiple vaccine strains to provide protection against multiple serotypes. In this study, we report the construction of a multivalent S. flexneri vaccine strain, SFL1425, expressing the O-antigen structure specific for serotypes 2a and 5a. This combination of type antigens has not previously been reported for S. flexneri. The multivalent vaccine strain, SFL1425 was able to induce a specific immune response against both serotypes 2a and 5a in a mouse pulmonary model. [source]


    Repetitive elements sequence (REP/ERIC)-PCR based genotyping of clinical and environmental strains of Yersinia enterocolitica biotype 1A reveal existence of limited number of clonal groups

    FEMS MICROBIOLOGY LETTERS, Issue 2 2004
    Pooja Sachdeva
    Abstract REP- and ERIC-PCR genotyping were used to assess genetic heterogeneity among 81 strains of Yersinia enterocolitica biotype 1A isolated from India, Germany, France and the USA. Although both gave comparable results, ERIC fingerprints discriminated the strains better. The rep- (REP and ERIC) PCR genotyping showed that strains having different serotypes produced identical rep-profiles indicating their limited genetic diversity. The concatenated dendrogram of REP- and ERIC-PCR fingerprints clustered the biotype 1A strains into two major groups. In each group, majority of the Indian, European and American strains exhibited similarities ranging from 85% to >95%. Similarity of rep-PCR fingerprints amongst strains isolated from widely separated geographical regions revealed existence of a limited number of clonal groups of Y. enterocolitica biotype 1A. The present study failed to reveal unequivocal relationships between rep-PCR genotypes and the source of isolation. However, the clinical serotype O:6,30-6,31 strains formed a tight cluster and the aquatic O:6,30-6,31 strains formed a yet another tight cluster. [source]


    Aroma of minor tropical fruits

    FLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2005
    M. R. B. Franco
    Abstract Publications on the volatile composition of some minor tropical fruits, i.e. acerola, cupuaçu, soursop, bacuri, genipap, umbu-cajá, araçá-boi, camu-camu, umbu, murici and cashew apple, are reviewed. Differences observed in the volatile composition of a same fruit could be due to the methodology and[sol ]or to different cultivars or geographical regions. Bound volatiles can also be liberated during the extraction procedures under drastic conditions. Copyright © 2005 John Wiley & Sons. Ltd. [source]


    Carp (Cyprinus carpio) as a powerful invader in Australian waterways

    FRESHWATER BIOLOGY, Issue 7 2004
    John D. Koehn
    Summary 1. The invasion of carp (Cyprinus carpio L.) in Australia illustrates how quickly an introduced fish species can spread and dominate fish communities. This species has become the most abundant large freshwater fish in south-east Australia, now distributed over more than 1 million km2. 2. Carp exhibit most of the traits predicted for a successful invasive fish species. In addition, degradation of aquatic environments in south-east Australia has given them a relative advantage over native species. 3. Derivation of relative measures of 13 species-specific attributes allowed a quantitative comparison between carp and abundant native fish species across five major Australian drainage divisions. In four of six geographical regions analysed, carp differed clearly from native species in their behaviour, resource use and population dynamics. 4. Climate matching was used to predict future range expansion of carp in Australia. All Australian surface waters appear to be climatically suitable for carp. 5. This assessment strongly reinforces the need for immediate management of carp in Australia to include targeted control of human-assisted dispersal, such as use of carp as bait by anglers, distribution to new locations by anglers and the use of the ,Koi' strain in the aquarium industry. 6. Given their historical spread, dispersal mechanisms and ecological requirements, the expansion of carp across most of the remainder of Australia is to be expected. [source]


    Post-merger strategy and performance: evidence from the US and European banking industries

    ACCOUNTING & FINANCE, Issue 4 2009
    Jens Hagendorff
    G21; G34; G28 Abstract The banking industry has one of the most active markets for mergers and acquisitions. However, little is known about the type of operational strategies adopted by banking firms in the years following a deal. For a sample of bidding banks in the USA and Europe, this study compares the design and performance implications of different post-merger strategies in both geographical regions. Using accounting data, we show that European banks pursue a cost-cutting strategy by increasing efficiency levels vis-à-vis non-merging banks and by cutting back on both labour costs and lending activities. US banks, on the other hand, raise both interest and non-interest income in the post-merger period. [source]


    Cost inefficiency and hospital health outcomes

    HEALTH ECONOMICS, Issue 7 2008
    Niccie L. McKay
    Abstract This study explores the association between cost inefficiency and health outcomes in a national sample of acute-care hospitals in the US over the period 1999,2001, with health outcomes being measured by both mortality and complications rates. The empirical analysis examines health outcomes as a function of cost inefficiency and other determinants of outcomes, using stochastic frontier analysis to obtain hospital cost inefficiency scores. The results showed no systematic pattern of association between cost inefficiency and hospital health outcomes; the basic results were unchanged regardless of whether cost inefficiency was measured with or without using instrumental variables. The analysis also indicated, however, that the association between cost inefficiency and health outcomes may vary substantially across geographical regions. The study highlights the importance of distinguishing between ,good' costs that reflect the efficient use of resources and ,bad' costs that stem from waste and other forms of inefficiency. In particular, the study's results suggest that hospital programs focused on reducing cost inefficiency are unlikely to be associated with worsened hospital-level mortality or complications rates, while, on the other hand, across-the-board reductions in cost could well have adverse consequences on health outcomes by reducing efficient as well as inefficient costs. Copyright © 2007 John Wiley & Sons, Ltd. [source]


    Survey ranking of job competencies by perceived employee importance: Comparing China's three regions

    HUMAN RESOURCE DEVELOPMENT QUARTERLY, Issue 4 2006
    Jin Xiao
    The acquisition of skills that match job requirements has become an issue in human resource development. A uniform but vague list of desirable skills often provided by policymakers or advocated by scholars is used as a guide in education and training programs in China. Using survey data, this study analyzes the core skills that workforces in China consider to be important in carrying out job routines in different jobs, different industries, and different geographical regions. This study surveyed 25,933 employees from 397 randomly sampled firms of four counties in each of the East, Central, and West regions of China. Twenty kinds of job skills were deduced from interviews conducted in the field. Five categories of skills were identified by the employees: dispositional characteristics, technical know-how skills, job basics, problem solving, and communication. Using a hierarchical model, the analysis is focused on whether employees in different occupations ( for example, managerial, professional, salesperson, frontline workers) had different perceptions of required job skills. The results show both differences related to occupation and work experience and similarities in perceived job competencies among industries and across three regions. [source]


    Trends in childhood acute lymphoblastic leukemia in Western Australia, 1960,2006

    INTERNATIONAL JOURNAL OF CANCER, Issue 5 2008
    Elizabeth Milne
    Abstract Increases in the incidence of childhood acute lymphoblastic leukemia (ALL) have been reported in some countries, while other reports from similar geographical regions have indicated stable rates. The reasons for the discrepancies have been debated in the literature, with the focus on whether the observed increases are "real" or an artifact resulting from improvements in diagnosis, case ascertainment and population coverage over time. We used population-based data from Western Australia to investigate trends in the incidence of childhood ALL between 1960 and 2006. Age-standardized incidence rates (ASRs) and rate ratios (indicating annual percent change) were estimated using Poisson regression. Between 1960 and 2006, the ASR was 3.7 per 100,000 person-years, with an annual percent increase of 0.40% (95% CI: ,0.20, 1.00). Between 1982 and 2006, the ASR was 3.8, with an annual percent increase of 0.80% (95% CI = ,0.70 to 2.30). This increased to 1.42% (95% CI: ,0.30, 3.0) when a sensitivity analysis was undertaken to assess the effect of excluding the final 2 years of data. Annual increases of 3.7% (95% CI: ,0.50, 8.00) among children aged 5,14 years, and of 3.10% (95% CI: 0.50, 5.70) in girls, were observed for this latter period. These results were supported by national Australian incidence data available for 1982,2003. There may have been a small increase in the incidence of ALL since 1982 among girls and older children, but an overall increase appears unlikely. No impact of folate supplementation or fortification is apparent. © 2007 Wiley-Liss, Inc. [source]


    Patterns of variability in the satellite microwave sounding unit temperature record: comparison with surface and reanalysis data

    INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 15 2003
    Giovanni Sturaro
    Abstract Principal component analysis is applied to global temperature records to study the differences in the patterns of variability between surface and troposphere. Surface, Microwave Sounding Unit (lower troposphere, channel 2 and channel 4) and National Centers for Environmental Prediction,National Center for Atmospheric Research reanalysis thickness data are studied in the common period 1979,2000. The patterns of variability are classified into geographical regions and compared. The series of their time coefficients are correlated to assess the existence of common and significant climate-change signals in the form of climatic trends. The objective is to identify the physical processes determining the records' variations and the differences between the surface and the satellite records that might be related to the discrepancy in their globally averaged trend. Major differences were found in the Tropics, where the surface warming is not paralleled in any other record. The surface record has two major patterns over the Tropics, one of which is connected to El Niño,southern oscillation. Satellite variability is instead described by only one pattern, most probably deriving from the merging of the two distinct patterns found for the near-surface records. In the eastern Antarctic a higher troposphere and lower stratosphere negative trend is found connected to ozone depletion. This signal prevails in the satellite record, despite evidence that it is confined only above 500 hPa. A pattern over Siberia is linked to the ,Euro-Siberian oscillation', i.e. the change in the pressure field determining the tracks of the Atlantic storms over the area Copyright © 2003 Royal Meteorological Society [source]


    Microwave depolarization versus rain attenuation on earth space in Malaysia

    INTERNATIONAL JOURNAL OF SATELLITE COMMUNICATIONS AND NETWORKING, Issue 6 2008
    J. S. Mandeep
    Abstract The wave propagation experiments using Japanese geostationary satellite Superbird-C have been performed at the Universiti Sains Malaysia earth station. A relationship between rain depolarization and attenuation, valid for earth-space path at microwave wavelengths, is presented. Cumulative rain attenuation and cross-polarization discrimination (XPD) statistics are given for the period of 4 years (2002,2005) at 12.255,GHz. XPD varied from 44,dB at 1% to 16,dB at 0.001% of time the abscissa is exceeded. Comparisons were made with available data sets and with five simple XPD models and the results indicate a good performance by the simple isolation model and the CHU model compared with the others. These results serve as checks on the theoretical models needed for predicting communication system performance in geographical regions especially for equatorial climate where measurements are not available. Copyright © 2008 John Wiley & Sons, Ltd. [source]


    Organizational culture in nursing schools in Turkey: faculty members' perspectives

    INTERNATIONAL NURSING REVIEW, Issue 3 2009
    F. Kantek rn
    Background:, Among the benefits of examining an organization's culture are the opportunity to understand the basic mechanisms of the institutional and structural procedures, to determine the need for change and to ensure the development and satisfaction of the faculty members. Aim:, To determine the perceptions of faculty members of organizational culture at nursing schools in Turkey and to examine different perceptions in relation to demographic variables. Method:, The study was conducted with 180 faculty members from seven nursing schools in state universities located in different geographical regions of Turkey that granted permission for the study. All faculty members in these schools with at least 1 year of institutional experience were included in the research. No sampling was required. A demographic information form and an organizational culture scale were used as data collection materials. The organizational culture scale contains 30 items and resolves the organizational culture in three dimensions. The minimum score obtained was 1 and the maximum was 5. Findings:, The mean score for faculty members' in total scale was 3.40 (SD = 0.68), while it was 3.26 (SD = 0.77) for the management style dimension, 3.39 (SD = 0.73) for the organizational commitment/relations dimension and 3.68 (SD = 0.73) for the student-oriented dimension. There was no statistical difference between the perception of organizational culture and work experience at the institution, marital status or educational status, but there were differences in age, number of years in the profession and academic titles. Conclusion:, It was found that strong perceptions have been established in nursing schools in regard to student-oriented practices, and that groups consisting of senior academic personnel and experienced academicians are considered to be better at perceiving the importance of the organizational culture. The administrators are recommended to promote policies to enhance the participation in decision-making processes and regularly monitor the cultural changes in the organization. [source]


    Leaf Quality of Some Tropical and Temperate Tree Species as Food Resource for Stream Shredders

    INTERNATIONAL REVIEW OF HYDROBIOLOGY, Issue 1 2010
    Manuel A. S. Graça
    Abstract We tested the hypotheses that (1) plant defenses against consumers increase in the tropics, and that these differences in quality are perceived by detritivores; and (2) microbial conditioning of leaf litter is important for the feeding ecology of shredders from both geographical regions. We compared quality parameters of 8 tree species from Portugal and 8 from Venezuela. The tropical leaves were tougher, but did not differ from temperate leaves in terms of N, C: N, and polyphenols. In multiple-choice experiments, shredders from Portugal (Sericostoma vittatum and Chaetopteryx lusitanica) and from Venezuela (Nectopsyche argentata and Phylloicus priapulus) discriminated among conditioned leaves, preferentially consuming softer leaves. In another set of experiments, all shredders preferentially fed on conditioned rather than unconditioned leaves, grew faster when fed conditioned than unconditioned leaves and fed more on temperate than tropical leaves. We conclude that leaf litter from the tropics is a low-quality resource compared to leaves in temperate systems, because of differences in toughness, and that tropical shredders benefit from microbial colonization, as previously demonstrated for temperate systems. We suggest that leaf toughness could be one explanation for the reported paucity of shredders in some tropical streams. (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]


    Adaptive radiation into ecological niches with eruptive dynamics: a comparison of tenthredinid and diprionid sawflies

    JOURNAL OF ANIMAL ECOLOGY, Issue 3 2005
    PETER W. PRICE
    Summary 1We tested the hypothesis that the bottom-up influence of coniferous plant resources promotes the probability of outbreak or eruptive dynamics in sawflies. The literature was examined for three geographical regions , North America north of Mexico, Europe and Japan. 2In each region tenthredinid sawflies (Hymenoptera: Tenthredinidae) were significantly more likely to be eruptive on conifers than on angiosperms. 3The diprionid sawflies (Hymenoptera: Diprionidae) that attack conifers exclusively showed a significantly higher probability of eruptive dynamics than the tenthredinid sawflies on angiosperms in two regions, North America and Europe, and in Japan the trend was in the same direction. 4The probability of species showing eruptive dynamics on coniferous hosts was not significantly different among tenthredinids and diprionids on conifers in North America, Europe and Japan. 5The weight of evidence supports the hypothesis of conifers supporting a higher percentage of eruptive species than angiosperms. 6In the adaptive radiation of tenthredinid sawflies from flowering plants onto conifers, larches (Larix) appear to be particularly favourable for colonization, but pines (Pinus) have not been colonized in any region, a pattern likely to be explained by the growth characteristics of the host plants. 7Among tenthredinid species in Europe, where sawfly/host relationships are best known, there is a significant trend for an increasing proportion of outbreaking species from herbs, to shrubs, to trees. 8The results indicate for the first time the strong bottom-up effects of plant resources on the population dynamics of sawflies, involving general features of host plant taxa and growth characteristics. [source]


    The influence of spatial errors in species occurrence data used in distribution models

    JOURNAL OF APPLIED ECOLOGY, Issue 1 2008
    Catherine H Graham
    Summary 1Species distribution modelling is used increasingly in both applied and theoretical research to predict how species are distributed and to understand attributes of species' environmental requirements. In species distribution modelling, various statistical methods are used that combine species occurrence data with environmental spatial data layers to predict the suitability of any site for that species. While the number of data sharing initiatives involving species' occurrences in the scientific community has increased dramatically over the past few years, various data quality and methodological concerns related to using these data for species distribution modelling have not been addressed adequately. 2We evaluated how uncertainty in georeferences and associated locational error in occurrences influence species distribution modelling using two treatments: (1) a control treatment where models were calibrated with original, accurate data and (2) an error treatment where data were first degraded spatially to simulate locational error. To incorporate error into the coordinates, we moved each coordinate with a random number drawn from the normal distribution with a mean of zero and a standard deviation of 5 km. We evaluated the influence of error on the performance of 10 commonly used distributional modelling techniques applied to 40 species in four distinct geographical regions. 3Locational error in occurrences reduced model performance in three of these regions; relatively accurate predictions of species distributions were possible for most species, even with degraded occurrences. Two species distribution modelling techniques, boosted regression trees and maximum entropy, were the best performing models in the face of locational errors. The results obtained with boosted regression trees were only slightly degraded by errors in location, and the results obtained with the maximum entropy approach were not affected by such errors. 4Synthesis and applications. To use the vast array of occurrence data that exists currently for research and management relating to the geographical ranges of species, modellers need to know the influence of locational error on model quality and whether some modelling techniques are particularly robust to error. We show that certain modelling techniques are particularly robust to a moderate level of locational error and that useful predictions of species distributions can be made even when occurrence data include some error. [source]


    Genetic structure of Hypochaeris uniflora (Asteraceae) suggests vicariance in the Carpathians and rapid post-glacial colonization of the Alps from an eastern Alpine refugium

    JOURNAL OF BIOGEOGRAPHY, Issue 12 2007
    Patrik Mráz
    Abstract Aim, The range of the subalpine species Hypochaeris uniflora covers the Alps, Carpathians and Sudetes Mountains. Whilst the genetic structure and post-glacial history of many high-mountain plant taxa of the Alps is relatively well documented, the Carpathian populations have often been neglected in phylogeographical studies. The aim of the present study is to compare the genetic variation of the species in two major European mountain systems , the Alps and the Carpathians. Location, Alps and Carpathians. Methods, The genetic variation of 77 populations, each consisting of three plants, was studied using amplified fragment length polymorphism (AFLP). Results, Neighbour joining and principal coordinate analyses revealed three well-supported phylogeographical groups of populations corresponding to three disjunct geographical regions , the Alps and the western and south-eastern Carpathians. Moreover, two further clusters could be distinguished within the latter mountain range, one consisting of populations from the eastern Carpathians and the second consisting of populations from the southern Carpathians. Populations from the Apuseni Mountains had an intermediate position between the eastern and southern Carpathians. The genetic clustering of populations into four groups was also supported by an analysis of molecular variance, which showed that most genetic variation (almost 46%) was found among these four groups. By far the highest within-population variation was found in the eastern Carpathians, followed by populations from the southern and western Carpathians. Generally, the populations from the Alps were considerably less variable and displayed substantially fewer region-diagnostic markers than those from the south-eastern Carpathians. Although no clear geographical structure was found within the Alps, based on neighbour joining or principal coordinate analyses, some trends were obvious: populations from the easternmost part were genetically more variable and, together with those from the south-western part, exhibited a higher proportion of rare AFLP fragments than populations in other areas. Moreover, the total number of AFLP fragments per population, the percentage of polymorphic loci and the proportion of rare AFLP fragments significantly decreased from east to west. Main conclusions, Deep infraspecific phylogeographical gaps between the populations from the Alps and the western and south-eastern Carpathians suggest the survival of H. uniflora in three separate refugia during the last glaciation. Our AFLP data provide molecular evidence for a long-term geographical disjunction between the eastern and western Carpathians, previously suggested from the floristic composition at the end of 19th century. It is likely that Alpine populations survived the Last Glacial in the eastern part of the Alps, from where they rapidly colonized the rest of the Alps after the ice sheet retreated. Multiple founder effects may explain a gradual loss of genetic variation during westward colonization of the Alps. [source]


    Historical biogeography of scarabaeine dung beetles

    JOURNAL OF BIOGEOGRAPHY, Issue 9 2002
    Adrian L. V. Davis
    Abstract Aim, (1) To review briefly global biogeographical patterns in dung beetles (Coleoptera: Scarabaeidae: Scarabaeinae), a group whose evolutionary history has been dominated by ecological specialization to vertebrate dung in warmer climates. (2) To develop hypotheses accounting for the evolution of these patterns. Location, Six principal biogeographical regions: Palaearctic, Oriental, Afrotropical, Australasia, Neotropical, Nearctic and five outlying islands or island groups harbouring endemic genera: Caribbean, Madagascar, Mauritius, New Caledonia, New Zealand. Methods, Major patterns of tribal, generic and species distribution are investigated using cluster analysis, ordination, parsimony analysis of endemism and track analysis. Attempts are made to resolve biogeographical patterns with findings in the fields of plate tectonics, fossil and evolutionary history, plus phylogeny of both mammals and dung beetles. Results, Because of conflict between published findings, it is uncertain at what point in time density of dinosaur dung, mammal dung or both became sufficiently great to select for specialized habits in dung beetles. However, biogeographical evidence would suggest a Mesozoic origin followed by further taxonomic radiation during the Cenozoic, possibly in response to the increasing size and diversity of mammalian dung types in South America and Afro-Eurasia. Proportional generic distribution in fourteen tribes and subtribes showed four principal biogeographical patterns: (1) southerly biased Gondwanaland distribution, (2) Americas or (3) Madagascar endemism, and (4) northerly biased, Afro-Eurasian-centred distribution with limited numbers of genera also widespread in other regions. Proportional composition of faunas in eleven geographical regions indicated three principal distributional centres, East Gondwanaland fragments, Afro-Eurasia and the Americas. These patterns probably result from three principal long-term range expansion and vicariance events (Mesozoic: Gondwanaland interchange and fragmentation, Cenozoic: Afro-Eurasian/Nearctic interchange and the Great American interchange). It is suggested that old vicariance caused by the Mesozoic fragmentation of Gondwanaland leads to a high degree of regional endemism at generic or tribal level across one or more Gondwanaland tracks. In contrast, it is suggested that the more recent Cenozoic range expansions occurred primarily towards northern regions leading to endemism primarily at species level. These Cenozoic radiations were facilitated by the re-linking of continents, either because of tectonic plate movements (Africa to Eurasia in Miocene), climatically induced sea-level change (Afro-Eurasia to Nearctic in Miocene and Pleistocene), or similar coupled with orogenics (Nearctic to Neotropical in Pliocene). Speciation has followed vicariance either because of climatic change or physical barrier development. These recent range expansions probably occurred principally along an Afro-Eurasian land track to the Nearctic and Neotropical and an Americas land track northwards from the Neotropics to the Nearctic, with limited dispersal from Eurasia to Australia, probably across a sea barrier. This accounts for the overall, spatially constrained, biogeographical pattern comprising large numbers of species-poor genera endemic to a single biogeographical region and fewer more species-rich genera, many of which show wider biogeographical distributions. In most southerly regions (Australasia, Madagascar, Neotropical), faunal composition and generic endemism is primarily dominated by elements with Gondwanaland ancestry, which is consistent with the Gondwanaland origin claimed for Scarabaeinae. In Afro-Eurasia (Palaearctic, Oriental, Afrotropical), generic endemism of monophyletically derived Afro-Eurasian and widespread lineages is centred in the Afrotropical region and faunal composition is numerically dominated by Afro-Eurasian and widespread elements. In the Nearctic region, the fauna is jointly dominated by widespread elements, derived from Afro-Eurasia, and Gondwanaland and Americas elements derived from the Neotropical region. Main conclusions, Global biogeographical patterns in scarabaeine dung beetles primarily result from Mesozoic and Cenozoic range expansion events followed by vicariance, although recent dispersal to Australia may have occurred across sea barriers. Detailed phylogenetics research is required to provide data to support dispersal/vicariance hypotheses. [source]


    The regulation of ecosystem functions by ecotypic variation in the dominant plant: a Spartina alterniflora salt-marsh case study

    JOURNAL OF ECOLOGY, Issue 1 2002
    Denise M. Seliskar
    Summary 1Genetic differences among populations of a keystone species may affect ecosystem functional properties. We tested this by planting Spartina alterniflora from different geographical regions in a newly created salt marsh in Delaware, USA. 2Spartina alterniflora plants from morphologically distinct short-form (back marsh) populations were originally collected from Massachusetts (41°34, N), Delaware (38°47, N), and Georgia (31°25, N) in the USA and vegetatively propagated for 6 years in a salt water-irrigated common garden in Delaware before transfer to a newly created salt marsh. 3The magnitude of the expression of marsh functions in the created marsh, measured over 5 years, remained distinct in patches of each ecotype. End of season aerial biomass, below-ground biomass, root and rhizome distribution, canopy height, stem density, and carbohydrate reserves were closer to values reported for the plants' native sites than to those typical of Delaware. Thus, many of the plant features characteristic of particular latitudes appear to be under genetic control. Such ecotypic differentiation influences ecosystem function through keystone resource and keystone modifier activities. 4Respiration of the microbial community associated with either dead shoots or the soil varied with plant ecotype in the created wetland and the patterns reflected those reported for their native sites. High edaphic respiration under the Massachusetts ecotype was correlated with the high percentage of sugar in the rhizomes. Edaphic chlorophyll was greater under the canopies of the Massachusetts and Delaware ecotypes than under the Georgia canopy and exhibited a relationship similar to that of algal production rates reported for the native sites. Larval fish were most abundant in pit traps in the Massachusetts ecotype. [source]


    Genetic characterization of hepatitis C virus strains in Estonia: Fluctuations in the predominating subtype with time

    JOURNAL OF MEDICAL VIROLOGY, Issue 4 2007
    Tatjana Tallo
    Abstract During the last decade, there has been a dramatic increase in intravenous drug use in young adults in Estonia with an increased incidence of both hepatitis B and C as a consequence. Since genetic data are limited regarding hepatitis C virus (HCV) strains in Estonia, the aim of the study was to characterize HCV strains in different risk groups to determine their relatedness to strains from other geographical regions. Three hundred fifty-three anti-HCV positive sera collected during 1994,2004 from hospitalized patients, blood donors and health care workers were used as source of HCV RNA. Two hundred nine (59%) of the sera were positive for HCV RNA by PCR directed to the 5,-UTR region. For 174 strains the HCV subtype was determined by analyses of the NS5B and/or the 5,UTR-core regions. 1b (71%) was the most common subtype followed by 3a (24%), 2c (2%), 1a (1%), and 2a (1%). The 1b and 3a strains were similar to strains from other regions of the former USSR. Within genotype 1b there were several HCV lineages. However, for 3a there seemed to be two separate introductions into Estonia. There was a relative shift from subtype 1b to 3a in 1999,2000 with a further replacement of 3a with 1b in intravenous drug users in 2001 and onwards (P,<,0.05). However, both subtypes were found to co-circulate in the community independent of risk factors. One patient was infected with the 2k/1b recombinant presumed to originate from St. Petersburg being the first isolate of this recombinant recovered outside Russia. J. Med. Virol. 79:374,382, 2007. © 2007 Wiley-Liss, Inc. [source]


    Comparative Sequence Analysis of Coat Protein Gene of Iranian Citrus tristeza virus Isolates

    JOURNAL OF PHYTOPATHOLOGY, Issue 7-8 2005
    A. Barzegar
    Abstract Twenty-two isolates of Citrus tristeza virus (CTV) collected from two different geographical regions of Iran were characterized based on coat protein (CP) gene sequences. Thirteen virus isolates were collected from northern parts of Iran with high distribution of CTV infection and nine isolates were obtained from southern regions where the presence and aphid transmission of CTV was previously reported. All isolates were recovered from field trees showing varied CTV symptoms such as decline in most citrus varieties on sour orange rootstock, inverse pitting on some sour orange rootstocks below bud union, mild-to-moderate stem pitting on the trunk of some sweet orange. Isolates F, G, MB1, MB7, MB2, MB8, MB9, MB11 and MB17 were recovered from healthy looking Miyagawa Satsuma on trifoliate rootstock originally infected with CTV imported from Japan in late-1960s. The presence of virus in citrus samples was confirmed using polyclonal as well as monoclonal antibody. The CTV CP gene of all isolates was amplified by reverse transcriptase polymerase chain reaction (RT,PCR) using CP gene-specific primers yielding 672 bp amplicon. The restriction fragment length polymorphism (RFLP) profile, nucleotide and deduced amino acid sequences were analysed and compared with each other and also with some other exotic CP gene sequences of CTV isolates available in GenBank. Analysis of our data revealed that Iranian isolates have high similarity to California SY568 severe stem pitting and Japanese NUagA seedling yellows strains (up to 97%). The dendrogram generated from the deduced amino acid sequence could separate MB1, MB2, MB8, MB9, MB11 and MB17 isolates from others. However, no major dissociation between the isolates from northern and southern region could be obtained. [source]


    Isozyme Analysis and Soluble Mycelial Protein Pattern in Iranian Isolates of Several formae speciales of Fusarium oxysporum

    JOURNAL OF PHYTOPATHOLOGY, Issue 5 2004
    M. Mohammadi
    Abstract A total of 13 representative isolates of Fusarium oxysporum f. sp. melonis (FOM) from Iran, USA and France, eight isolates of seven formae speciales from Iran and one isolate of F. oxysporum f. sp. niveum from the USA were compared based on isozyme analysis and soluble mycelial protein pattern. Isozyme analyses of alkaline phosphatase (ALP), catalase (CAT), esterase (EST), malate dehydrogenase (MDH), superoxide dismutase (SOD) and xanthine dehydrogenase (XDH) revealed polymorphism among the F. oxysporum isolates in which 22 electrophoretic phenotypes (EP) were determined. At least 10 putative loci for these six enzymes were detected and they were all polymorphic. Maximum genetic diversity was observed in CAT, EST and XDH loci. Using UPGMA, the 22 isolates were separated into three main groups with one of the groups divided into two subgroups. Group I included isolates belonging to five formae speciales from Iran, whereas group II that included FOM isolates from both Iran and the USA was divided into two subgroups each containing the vast majority of the respective isolates from either country. Group III constituted FOM isolates from France and one pathogenic isolate on pepper from Iran. FOM isolates representing five different geographical regions from Iran belonged to two different races of 1 and 1,2Y and one vegetative compatibility group (VCG)0134 and thus were genetically homologous. Isozyme polymorphism in these isolates was highly correlated with VCG and geographical origins and to a lesser extent with races. Variations in soluble protein profile in FOM isolates were correlated with genetic distances determined in isozyme analysis. This study suggests that isozyme analysis could be a useful tool for identifying genetic diversity not only in FOM but also several formae speciales of F. oxysporum. [source]


    A Seven-Year Follow-Up Comparing Attendees and Nonattendees at a Statewide, School Employee Wellness Conference

    JOURNAL OF SCHOOL HEALTH, Issue 4 2001
    Gay James PhD Associate Professor
    ABSTRACT: This study involved a follow-up assessment of the status of school employee wellness programs in the same matched comparison groups examined in 1992. In spring 1999, surveys were mailed to the 98 Texas school districts that sent employees to the statewide health promotion conference at least once during 1988,1991, and to the matched comparison group of 98 nonattendees during 1988,1991. Groups were matched on geographical regions, enrollment, and expenditure per pupil. Follow-up survey response rates were 59% for the attendee group and 54% for the nonattendee group. Although the follow-up survey results indicated no significant differences between groups, attendee group respondents reported offering more active employee wellness programs. [source]