1,537 research outputs found

    Extinctions of aculeate pollinators in Britain and the role of large-scale agricultural changes

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    Pollinators are fundamental to maintaining both biodiversity and agricultural productivity, but habitat destruction, loss of flower resources, and increased use of pesticides are causing declines in their abundance and diversity. Using historical records we assessed the rate of extinction of bee and flower-visiting wasp species in Britain, from the mid 19th century to the present. The most rapid phase of extinction appears to be related to changes in agricultural policy and practice beginning in the 1920s, before the agricultural intensification prompted by the Second World War, often cited as the most important driver of biodiversity loss in Britain. Slowing of the extinction rate from the 1960s onwards may be due to prior loss of the most sensitive species and/or effective conservation programs

    Robust Approximation to Adaptive Control by Use of Representative Parameter Sets with Particular Reference to Type 1 Diabetes

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    This paper describes an approach to adaptive optimal control in the presence of model parameter calculation difficulties. This has wide application in a variety of biological and biomedical research and clinical problems. To illustrate the techniques, the approach is applied to the development and implementation of a practical adaptive insulin infusion algorithm for use with patients with Type 1 diabetes mellitus

    Network analysis of phenological units to detect important species in plant-pollinator communities: can it inform conservation strategies?

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    Conservation of species is often focused either only on those that are endangered, or on maximising the number recorded on species lists. However, species share space and time with others, thus interacting and building frameworks of relationships that can be unravelled by community-level network analysis. It is these relationships that ultimately drive ecosystem function via the transfer of energy and nutrients. However interactions are rarely considered in conservation planning. Network analysis can be used to detect key species ("hubs") that play an important role in cohesiveness of networks. We applied this approach to plant-pollinator communities on two montane Northern Apennine grasslands, paying special attention to the modules and the identity of hubs. We performed season-wide sampling and then focused the network analyses on time units consistent with plant phenology. After testing for significance of modules, only some modules were found to be significantly segregated from others. Thus, networks were organized around a structured core of modules with a set of companion species that were not organized into compartments. Using a network approach we obtained a list of important plant and pollinator species, including three Network Hubs of utmost importance, and other hubs of particular biogeographical interest. By having a lot of links and high partner diversity, hubs should convey stability to networks. Due to their role in the networks, taking into account such key species when considering the management of sites could help to preserve the greatest number of interactions and thus support many other species

    The macroecology of animal versus wind pollination: ecological factors are more important than historical climate stability

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    Background: The relative frequency of wind and animal pollinated plants is non-randomly distributed across the globe and numerous hypotheses have been raised for the greater occurrence of wind pollination in some habitats and towards higher latitudes. To date, however, there has been no comprehensive global investigation of these hypotheses. Aims: Investigating a range of hypotheses for the role of biotic and abiotic factors as determinants of the global variation in animal versus wind pollination. Methods: We analysed 67 plant communities ranging from 70º North to 34º South. For these we determined habitat type, species richness, insularity, topographic heterogeneity, current climate and Late-Quaternary climate change. The predictive effects of these factors on the proportion of wind- and animal-pollinated plants were tested using correlations, ordinary least squares (OLS) and logistic regression analyses with information-theoretic model selection. Results: The proportion of animal-pollinated plant species was positively associated with plant species richness and current temperature. Furthermore, in forest, animal pollination was positively related to precipitation. Historical climate was only weakly and idiosyncratically correlated with animal pollination. Conclusion: Results were consistent with the hypothesised reduced chance for wind-transported pollen reaching conspecific flowers in species-rich communities, fewer constraints on nectar production in warm and wet habitats, and reduced relative effectiveness of wind dispersal in humid areas. There was little evidence of a legacy of historical climate change affecting these patterns

    The influence of floral traits on specialisation and modularity of plant-pollinator networks in a biodiversity hotspot in the Peruvian Andes

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    Background and Aims: Modularity is a ubiquitous and important structural property of ecological networks which describes the relative strengths of sets of interacting species and gives insights into the dynamics of ecological communities. However, this has rarely been studied in species-rich, tropical plant–pollinator networks. Working in a biodiversity hotspot in the Peruvian Andes we assessed the structure of quantitative plant–pollinator networks in nine valleys, quantifying modularity among networks, defining the topological roles of species and the influence of floral traits on specialization. Methods: A total of 90 transects were surveyed for plants and pollinators at different altitudes and across different life zones. Quantitative modularity (QuanBiMo) was used to detect modularity and six indices were used to quantify specialization. Key Results: All networks were highly structured, moderately specialized and significantly modular regardless of size. The strongest hubs were Baccharis plants, Apis mellifera, Bombus funebris and Diptera spp., which were the most ubiquitous and abundant species with the longest phenologies. Species strength showed a strong association with the modular structure of plant–pollinator networks. Hubs and connectors were the most centralized participants in the networks and were ranked highest (high generalization) when quantifying specialization with most indices. However, complementary specialization d' quantified hubs and connectors as moderately specialized. Specialization and topological roles of species were remarkably constant across some sites, but highly variable in others. Networks were dominated by ecologically and functionally generalist plant species with open access flowers which are closely related taxonomically with similar morphology and rewards. Plants associated with hummingbirds had the highest level of complementary specialization and exclusivity in modules (functional specialists) and the longest corollas. Conclusions: We have demonstrated that the topology of networks in this tropical montane environment was non-random and highly organized. Our findings underline that specialization indices convey different concepts of specialization and hence quantify different aspects, and that measuring specialization requires careful consideration of what defines a specialist

    Vegetation cover and grasslands in the vicinity accelerate development of carabid beetle assemblages on restored landfill sites

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    There is increasing evidence that rare and scarce carabid species of conservation importance are frequent in brownfield sites such as restored landfill. However, this potential has largely been unexplored and was investigated here by examining carabid species composition, richness, and abundance in relation to habitat quality and landscape structure on landfill sites in comparison to paired reference sites of existing wildlife value. Sampling was conducted by collecting carabids in ten pitfall traps set along two 100 m transects on each of nine restored landfill and their paired reference sites in the East Midlands region of the UK. A total of 1014 individuals representing thirty seven carabid species were found during April to September in 2007 and 2008. On the landfill sites, generalist species were common, while no nationally rare or scarce species were found. Neither species richness nor diversity of carabid species was found to be different from that of the reference sites. Seeding during restoration was found to have a strong positive effect on richness and diversity, with seeded landfill sites tending to be similar to reference sites in terms of carabid species composition. Marked differences in diversity and richness were also attributed to variation in the amount of local vegetation cover, with presence of grassland in the surrounding landscape having a positive effect on carabid assemblages. We suggest that initial seeding may be an appropriate conservation strategy to improve beetle diversity and richness, coupled with management in terms of cutting to increase the potential of these sites for carabid conservation at the landscape scale

    Cardiovascular disease in chinese women: An emerging high-risk population and implications for nursing practice

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    Globally, cardiovascular disease (CVD) is the leading cause of death among women. In China, the burden of CVD is increasing at an alarming rate; yet, it is underestimated and has important primary, secondary, and tertiary prevention issues. AIM:: This article seeks to document the issues surrounding the increased rate of CVD among Chinese women and describe the etiological factors and potential strategies to decrease the burden of disease. METHODS:: The Medline, Current Information in Nursing and Allied Health Literature, Ovid, Science Direct, and Government Reports were searched using the key words heart disease, cardiovascular, ischemic heart disease, coronary, women, and Chin (China, Chinese). Articles were selected if they described epidemiological factors and/or interventions to address heart disease in Chinese women. FINDINGS:: Rapid industrialization and urbanization in China have extended the life expectancy of the population, particularly among women. Social, political, and economic factors have caused lifestyle changes that have a direct bearing on health. Heart disease has become the most common cause of death among Chinese women and the second most common cause among men. Paradoxically, prevention and management strategies are sparse in relation to the high prevalence. A number of modifiable risk factors have been identified as major contributors of CVD and should be a focus of primary, secondary, and tertiary prevention. CONCLUSION:: Cardiovascular disease is already a leading cause of death and disability among Chinese women. The high prevalence of risk factors and low rate of awareness, treatment, and control signal an urgent need for focusing on this issue in Chinese women. Strategies on individual, community, and government levels are recommended. Involving Chinese nurses in these strategies is essential. © 2008 Lippincott Williams & Wilkins

    Global Trends in the Status of Bird and Mammal Pollinators

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    Biodiversity is declining, with direct and indirect effects on ecosystem func-tions and services that are poorly quantified. Here, we develop the first globalassessment of trends in pollinators, focusing on pollinating birds and mam-mals. A Red List Index for these species shows that, overall, pollinating birdand mammal species are deteriorating in status, with more species movingtoward extinction than away from it. On average, 2.5 species per year havemoved one Red List category toward extinction in recent decades, represent-ing a substantial increase in the extinction risk across this set of species. Thismay be impacting the delivery of benefits that these species provide to people.We recommend that the index be expanded to include taxonomic groups thatcontribute more significantly to pollination, such as bees, wasps, and butter-flies, thereby giving a more complete picture of the state of pollinating speciesworldwide

    Using the literature to test pollination syndromes — some methodological cautions

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    “Pollination syndromes” are specific combinations of floral traits that are proposed to evolve convergently across angiosperm lineages in response to different types of animal pollinators. In spite of their long history, pollination syndromes have not been tested adequately–they rarely have been examined critically to determine how well they describe floral trait diversity or predict pollinators. In a recent meta-analysis of data from the literature, Rosas-Guerrero et al. (2014) provide a welcome test that draws on insights from past studies. At the same time, their study illustrates several difficulties of meta-analysis approaches in general, and for pollination biology in particular. Here we discuss those difficulties and propose some solutions. We first consider how to gather studies from the literature without introducing unintended bias, such as the old-fashioned method of working backward from cited literature. We next consider how to deal with difficulties that invariably arise when extracting and analyzing often-incomplete information from heterogeneous studies. Finally we discuss issues of interpreting and presenting the results in the most informative manner. We conclude that although Rosas-Guerrero et al. (2014) and other studies such as Ollerton et al. (2009) have arrived at different conclusions about the utility of pollination syndromes, their results are not necessarily incompatible
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