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Using a novel database on venue short sales and market design characteristics, we ask: Where do short sellers exploit their information advantage? Consistent with the prediction of Zhu (2014), we find that exchange short sales comprise a larger proportion of trading and are more informative about future prices than dark-pool short sales, particularly when there is greater competition among short sellers to trade and in the presence of short-lived information. When examining market design characteristics, we find that dark pools offering volume-weighted average price crossing attract more short sales, whereas those offering block trading attract fewer short sales.
The conservation and management of peatlands by practitioners is often assumed to work best when guided by science (e.g. Maltby 1997). However, there are also many excellent peatland management and restoration projects, which have built upon years of practical experience (sometimes through trial and error), undertaken by organisations involved in hands-on peatland conservation. Parry, Holden and Chapman (2014) provide many examples of techniques developed through common sense and ingenuity on the part of practitioners, often with little input from the science community. Often restoration projects have to make progress well before the science is fully understood. Significant investment is being poured into peatland management projects across the world (Parish et al. 2008), and it is important for those investing resources in peatland environments that there is some evaluation of the impacts of such investment. Evaluating the success of peatland management projects may involve the scientific community (e.g. taking measurements of carbon fluxes). In many instances, however, practitioners may involve less stringent measures with success measured by recording some simple visible changes to the landscape. The evaluation of success may indeed be an economic one (Kent 2000) based on cost–benefit analyses (Christie et al. 2011) of, for example, money spent on restoration that has been or will be saved elsewhere through, for instance, improved water quality entering water company treatment works. The observations for measuring peatland conservation success may depend on spatial and temporal scale, geographic settings and project targets, as well as available expertise and funding. There are therefore questions about how we measure success and how scientists, practitioners and policy makers can work closely together to deliver the best outcomes for peatland ecosystem services. Careful attention should be given to the mechanisms for science knowledge exchange between science and practical application so that practical experience and knowledge by those managing peatlands is transferred into the scientific understanding of peatlands. Scientists value the opinions and ideas of the restoration community and there have been recent attempts to move towards improved co-design of research and co-production of knowledge of science and practitioner communities in peatland restoration environments (Reed 2008; Reed et al. 2009).
Taking an ecosystem services approach to peatland conservation means that scientists, practitioners and policy makers have to understand the wider interconnectedness of peatland processes that lead to the provision of goods and services to society.
This essay will address the developments in the literature on U.S. foreign relations from the perspectives of technology and the environment in the period since 1941. Only in the past fifteen years or so have diplomatic historians generally recognized these to be fruitful topics worth exploring at their intersections with foreign relations. Because of the comparative newness of such perspectives within the field, the rich debates or competing schools of thought that mark the literature on other topics have not yet developed. Therefore, a thematic approach to this area offers perhaps the best method to explore the principal ways that foreign relations historians have been thinking about technology and the environment in the global economy since mid-century. We can categorize this scholarship as dealing with weapons, energy, communications, transportation, export control, modernization theory, scientific expertise, and the environment. Because of space limitations, much of what follows in this essay is by necessity from a U.S. perspective. Nevertheless, the interconnectedness of the world means that multinational, multilingual, and multiarchival explorations of these topics are both ongoing and important in their own right.
Studies of recently isolated populations are useful because observed differences can often be attributed to current environmental variation. Two populations of the lizard Anolis lemurinus have been isolated on the islands of Cayo Menor and Cayo Mayor in the Cayos Cochinos Archipelago of Honduras for less than 15 000 y. We measured 12 morphometric and 10 habitat-use variables on 220 lizards across these islands in 2 y, 2008 and 2009. The goals of our study were (1) to explore patterns of sexual dimorphism, and (2) to test the hypothesis that differences in environment among islands may have driven divergence in morphology and habitat use despite genetic homogeneity among populations. Although we found no differences among sexes in habitat use, males had narrower pelvic girdles and longer toe pads on both islands. Between islands, males differed in morphology, but neither males nor females differed in habitat use. Our data suggest that either recent selection has operated differentially on males despite low genetic differentiation, or that they display phenotypic plasticity in response to environmental variation. We suggest that patterns may be driven by variation in intrapopulation density or differences in predator diversity among islands.
Rare bouts of extreme environmental perturbations (catastrophes) have been predicted to have a major influence on the probability of extinction. Yet very little information is available on the frequency and severity of catastrophes. Improving the available information concerning catastrophe parameters would allow for an evaluation of their effect and a start towards understanding their causes. We used the Global Population Dynamics Database to determine the frequency and severity of die-offs in 88 species of vertebrates. We define a catastrophe as any 1-year decrease in population size of 50% or greater. The data yielded three findings. (1) The frequency of severe die-offs in vertebrate populations is strongly related to the generation length of the organism. (2) The probability of a severe die-off for a particular population is approximately 14% per generation. (3) The frequency of die-off severity can be modelled as a modified power function with the frequency of die-offs decreasing with increasing magnitude of effect. The distribution is not consistent with catastrophes stemming from environmental sources different than those responsible for smaller fluctuations, but seems to represent the tail of a continuous distribution of environmental perturbations.
We sampled blood from free-living spotted salamanders (Ambystoma maculatum) to test whether differences in the concentrations of a stress hormone (corticosterone) were associated with different qualities of breeding and migration habitat. Spotted salamanders are forest specialists that migrate to vernal pools to breed, and upland habitat degradation may have sub-lethal effects on animals that lead to population declines. An individual's level of physiological stress may function as a biomonitor for sub-lethal effects, and thus as a biomonitor for ecosystem quality. We compared unstressed (baseline) and stress-induced corticosterone concentrations in spotted salamanders: (1) at sites that differed in amount of forest loss; (2) during breeding migration across forest habitat versus pavement; (3) in microhabitats that varied in soil drainage and canopy cover. Removal of large amounts of terrestrial habitat surrounding a breeding pond was correlated with lower baseline (in males) and stress-induced corticosterone concentrations, which may indicate healthy individuals with a reduced ability to respond to additional stress or individuals experiencing chronic stress. Male salamanders migrating across pavement had elevated baseline corticosterone concentrations compared to animals migrating through a forest, consistent with an acute stress response. However, concentrations of corticosterone did not differ between individuals in microhabitats with canopy cover and well-drained soil versus those in microhabitats with no canopy cover and/or swampy soil. This endocrinological technique may be one useful measure of a population's health, helping to identify populations where further ecological study is recommended to evaluate conservation concerns.