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1.
Evolutionary studies suggest that the potential for rapid emergence of novel host–parasite associations is a “built-in feature” of the complex phenomenon that is Darwinian evolution. The current Emerging Infectious Disease (EID) crisis is thus a new manifestation of an old and repeating phenomenon. There is evidence that previous episodes of global climate change and ecological perturbation, broadly defined, throughout earth history have been associated with environmental disruptions that produce episodic bursts of new host–parasite associations, each of which would have been called an EID at the time of its first appearance. This perspective implies that there are many evolutionary accidents waiting to happen, requiring only the catalyst of climate change, species introductions, and the intrusion of humans into areas they have never inhabited before.  相似文献   

2.
Climate change, as an environmental hazard operating at the global scale, poses a unique and “involuntary exposure” to many societies, and therefore represents possibly the largest health inequity of our time. According to statistics from the World Health Organization (WHO), regions or populations already experiencing the most increase in diseases attributable to temperature rise in the past 30 years ironically contain those populations least responsible for causing greenhouse gas warming of the planet. Average global carbon emissions approximate one metric ton per year (tC/yr) per person. In 2004, United States per capita emissions neared 6 tC/yr (with Canada and Australia not far behind), and Japan and Western European countries range from 2 to 5 tC/yr per capita. Yet developing countries’ per capita emissions approximate 0.6 tC/yr, and more than 50 countries are below 0.2 tC/yr (or 30-fold less than an average American). This imbalance between populations suffering from an increase in climate-sensitive diseases versus those nations producing greenhouse gases that cause global warming can be quantified using a “natural debt” index, which is the cumulative depleted CO2 emissions per capita. This is a better representation of the responsibility for current warming than a single year’s emissions. By this measure, for example, the relative responsibilities of the U.S. in relation to those of India or China is nearly double that using an index of current emissions, although it does not greatly change the relationship between India and China. Rich countries like the U.S. have caused much more of today’s warming than poor ones, which have not been emitting at significant levels for many years yet, no matter what current emissions indicate. Along with taking necessary measures to reduce the extent of global warming and the associated impacts, society also needs to pursue equitable solutions that first protect the most vulnerable population groups; be they defined by demographics, income, or location. For example, according to the WHO, 88% of the disease burden attributable to climate change afflicts children under age 5 (obviously an innocent and “nonconsenting” segment of the population), presenting another major axis of inequity. Not only is the health burden from climate change itself greatest among the world’s poor, but some of the major mitigation approaches to reduce the degree of warming may produce negative side effects disproportionately among the poor, for example, competition for land from biofuels creating pressure on food prices. Of course, in today’s globalized world, eventually all nations will share some risk, but underserved populations will suffer first and most strongly from climate change. Moreover, growing recognition that society faces a nonlinear and potentially irreversible threat has deep ethical implications about humanity’s stewardship of the planet that affect both rich and poor.  相似文献   

3.
The behavior of frogs from southern areas with an arid climate released during the reproductive period between their “home” pond and a less distant river is shown to be independent of weather conditions. The experiments were performed on frogs living near the village of Dosang, Astrakhan oblast. The frogs were released 60 to 150 m from their “home” breeding waterbody and 60 to 80 m from an “alien” waterbody. Four experiments were performed on 27 individuals. The movements of the frogs were traced by the method of “tracking by a thread.” The results revealed no preference in the frogs to return to their own breeding ponds, rather than to the nearby river. This behavior is peculiar to frogs of southern populations.  相似文献   

4.
This essay argues that what makes “global health” “global” has more to do with configurations of space and time, and the claims to expertise and moral stances these configurations make possible, than with the geographical distribution of medical experts or the universal, if also uneven, distribution of threats to health. Drawing on a study of public–private partnerships supporting Botswana’s HIV/AIDS treatment program, this essay demonstrates ethnographically the processes by which “global health” and its quintessential spaces, namely “resource-limited” or “resource-poor settings,” are constituted, reinforced, and contested in the context of medical education and medical practice in Botswana’s largest hospital. Using Silverstein’s work on orders of indexicality, I argue that the terms of “global health” are best understood as chronotopic, and demonstrate how actors orient themselves and others spatio-temporally, morally, and professionally by using or refuting those terms. I conclude by arguing that taking “global health” on its own terms obscures the powerful forces by which it becomes intelligible. At stake are the frames within which medical anthropologists understand their objects of study, as well as the potential for the spaces of “global health” intervention to expand ever outward as American medical personnel attempt to calibrate their experiences to their expectations.  相似文献   

5.
A four-site haplotype system at the dopamine D2 receptor locus (DRD2) has been studied in a global sample of 28 distinct populations. The haplotype system spans about 25 kb, encompassing the coding region of the gene. The four individual markers include three TaqI restriction site polymorphisms (RSPs) – TaqI “A”, “B”, and “D” sites – and one dinucleotide short tandem repeat polymorphism (STRP). All four of the marker systems are polymorphic in all regions of the world and in most individual populations. The haplotype system shows the highest average heterozygosity in Africa, a slightly lower average heterozygosity in Europe, and the lowest average heterozygosities in East Asia and the Americas. Across all populations, 20 of the 48 possible haplotypes reached a frequency of at least 5% in at least one population sample. However, no single population had more than six haplotypes reaching that frequency. In general, African populations had more haplotypes present in each population and more haplotypes occurring at a frequency of at least 5% in that population. Permutation tests for significance of overall disequilibrium (all sites considered simultaneously) were highly significant (P<0.001) in all 28 populations. Except for three African samples, the pairwise disequilibrium between the outermost RSP markers, TaqI “B” and “A”, was highly significant with D’ values greater than 0.8; in two of those exceptions the RSP marker was not polymorphic. Except for those same two African populations, the 16-repeat allele at the STRP also showed highly significant disequilibrium with the TaqI “B” site in all populations, with D’ values usually greater than 0.7. Only four haplotypes account for more than 70% of all chromosomes in virtually all non-African populations, and two of those haplotypes account for more than 70% of all chromosomes in most East Asian and Amerindian populations. A new measure of the amount of overall disequilibrium shows least disequilibrium in African populations, somewhat more in European populations, and the greatest amount in East Asian and Amerindian populations. This pattern seems best explained by random genetic drift with low levels of recombination, a low mutation rate at the STRP, and essentially no recurrent mutation at the RSP sites, all in conjunction with an “Out of Africa” model for recent human evolution. Received: 14 January 1998 / Accepted 19 March 1998  相似文献   

6.
In Landscapes and Labscapes Robert Kohler emphasized the separation between laboratory and field cultures and the creation of new “hybrid” or mixed practices as field sciences matured in the early twentieth century. This article explores related changes in laboratory practices, especially novel designs for the analysis of organism–environment relations in the mid-twentieth century. American ecologist Victor Shelford argued in 1929 that technological improvements and indoor climate control should be applied to ecological laboratories, but his recommendations were too ambitious for the time. In the postwar period Frits W. Went, plant physiologist at the California Institute of Technology, created a new high-tech laboratory, dubbed a “phytotron”, in the hope that it would transform plant sciences by allowing for unprecedented control of environmental variables. Went’s aspirations, the research conducted in his laboratory, and its impact in initiating an international movement, are considered. Went’s laboratory can be seen as a “hybrid culture” evolving in the laboratory, complementing and intersecting with some of the field practices that Kohler describes. It was also a countercultural movement against the reductionist trends of molecular biology in the 1950s and 1960s. By considering the history of the laboratory in relation to field sciences, we can explore how new funding sources and cross-disciplinary relations affected the development of field sciences, especially in the postwar period.  相似文献   

7.
We may consider that most of the human behavior is a set of learned responses to certain patterns which recur frequently in the course of human life. Some “abnormal” events or experiences may result in the learning of abnormal responses, and thus in abnormal behavior. The “abnormal” responses may begin to be learned after some of the normal response patterns have been fairly well established. The development of both normal and abnormal behavior may thus be represented by learning curves of the type studied by H. D. Landahl. Applying some of the results of the theory of learning curves and considering that the normal and abnormal reactions may reciprocally inhibit each other, a quantitative theory of some psychoses may be developed. In particular, the effects of shock may be deduced from the assumption that they cause the more recently learned abnormal reactions to be “unlearned” more readily, than the earlier learned “normal” reactions. The effectiveness of shock treatments as a function of the duraction of psychosis is discussed from this point of view.  相似文献   

8.
The Ortolan bunting Emberiza hortulana was censused in Poland during the Common Breeding Birds Monitoring Project in 2003–2009. Data from 683 monitoring polygons, covering in total more than 0.23% of the country, were used in the analysis. Based on the data and environmental information gathered in GIS databases (Corine land cover “CLC2000 and 2006” database, digital elevation model “GTOPO30” dataset, “Wordclim” dataset, and NDVI dataset), we modeled a habitat- and spatial-related variation of the Ortolan bunting’s presence. Birds were recorded in 13.2% grid cells. The mean density was 0.5 individual/km2. We modeled the spatial presence of birds using multivariate adaptive regression splines (MARS). Then models were cross-validated to check their consistency. The environment-use model shows that the Ortolan bunting prefers extensively cultivated farmland dominated by non-irrigated arable fields, small coniferous and mixed forests, complex cultivation patterns, and meadows. The preferred areas are located on lowlands in western and central parts of the country where the climate is the driest and warmest. Such a repeatable spatial pattern model of the population helped to create a predictive map of the Ortolan bunting’s presence in Poland. The general rule is that the probability gradient of its presence increases from the northeastern part of the country to the central and southwestern parts of Poland. Additionally, the Ortolan bunting avoids severe continental climate and regions with dense ground-level vegetation.  相似文献   

9.
The classical approach of evolutionism is based on the concept of the survival of the fittest individuals. More and more data indicate that natural selection often acts with supra-individual mechanisms favoring genes and actions harmful for the individual. The most striking type of cases is when an individual kills himself or his offspring by actions genetically determined or favored. The neologism “phenoptosis” describes these events and implicates that they are not evolutionary anomalies but physiological phenomena determined by natural selection. The most important and familiar kind of phenoptosis, the “slow phenoptosis” or aging, which is currently considered an inevitable and scarcely changeable event, is transformed by this different interpretation into a function, in principle modifiable and manageable. Perhaps, the neologism “phenoptosis” will represent, together with the term supra-individual selection, the mark of a vital enrichment of evolutionism, conceived in broader terms of which the individual selection is just a particular case, and will be referred to as the brand and the standard for the start of a new era.  相似文献   

10.
Swidden agriculture, commercial logging and plantation development have been considered to be the primary common causes of degradation and loss of tropical rain forests in Southeast Asia. In this paper, I chose a part of northeastern Sarawak, East Malaysia as my case study area to analyze the changes in its land-use characteristics. In the study area, as well as primeval forests, we see that land use began about 100 years ago by a native group called the Iban; commercial logging began in the 1960s, and the development of oil palm plantations began recently. I describe the changes in land use as well as their social and economic causes by referring to aerial photographs, literature surveys, interviews with government officers and the Iban, and observation of land use. My analysis of land use demonstrates that on “state land”, where commercial logging and oil palm plantation development are occurring, large areas of forest have been disturbed in a short period of time. The objective is to benefit economically in response to the social and economic conditions surrounding the study area. On the other hand, in the “Iban territory,” where the Iban practice their land use, land conversion has not occurred on a large scale and in a short period of time, even though the forest has been cut and agricultural fields have been created in response to social and economic conditions as well. They disperse small agricultural fields throughout their forest land. Therefore, the landscape of the “Iban territory” is based on secondary forest, composed of patches of forest in various stages and with several types of agricultural land. Today in Sarawak, monocrop plantations are rapidly expanding and little primeval forest remains. Given these conditions, the land-use practices of natives such as the Iban will be evaluated from the viewpoint of ecosystem and biodiversity conservation. It could play an important role in providing habitats for natural wildlife.  相似文献   

11.
The present study was undertaken to evaluate non-random mating patterns in two groups of mantled howler monkeys in two tropical dry forest habitats. Sexual dimorphism, female estrus stage, male dominance rank, sexual solicitations and copulations were assessed. Males are significantly larger than females, but female weight varies more than male weight. The length of female estrus cycles is comparable in both habitats, but females in the more strongly seasonal habitat demonstrate greater estrus synchrony relative to their numbers. Males solicit potential mates more frequently than females, a pattern explained by the relatively high rate of sexual solicitation by high-ranking males. Females in “peak” estrus solicit “alpha” males, while females in other stages of estrus solicit males equally by rank. Intersexual aggression occurs rarely, and “forced copulations” are attempted but, apparently, are unsuccessful. Sexual solicitations by “alpha” males and “peak” estrus females are most likely to lead to copulation, and “alpha” males are more likely to copulate than “gamma” males. In general, latencies from first solicitation to copulation are expensive in time, especially for high-ranking males. Estimated annual reproduction success favors high-ranking males, and results indicate that male and female mating behavior is mutually coordinated and controlled.  相似文献   

12.
Introduced species, those dispersed outside their natural ranges by humans, now cause almost all biological invasions, i.e., entry of organisms into habitats with negative effects on organisms already there. Knowing whether introduction tends to give organisms specific ecological advantages or disadvantages in their new habitats could help understand and control invasions. Even if no specific species traits are associated with introduction, introduced species might out-compete native ones just because the pool of introduced species is very large (“global competition hypothesis”). Especially in the case of intentional introduction, high initial propagule pressure might further increase the chance of establishment, and repeated introductions from different source populations might increase the fitness of introduced species through hybridization. Intentional introduction screens species for usefulness to humans and so might select for rapid growth and reproduction or carry species to suitable habitats, all which could promote invasiveness. However, trade offs between growth and tolerance might make introduced species vulnerable to extreme climatic events and cause some invasions to be transient (“reckless invader hypothesis”). Unintentional introduction may screen for species associated with human-disturbed habitats, and human disturbance of their new habitats may make these species more invasive. Introduction and natural long-distance dispersal both imply that species have neither undergone adaptation in their new habitats nor been adapted to by other species there. These two characteristics are the basis for many well-known hypotheses about invasion, including the “biotic resistance”, “enemy release”, “evolution of increased competitive ability” and “novel weapon” hypotheses, each of which has been shown to help explain some invasions. To the extent that biotic resistance depends upon local adaption by native species, altering selection pressures could reduce resistance and promote invasion (“local adaptation hypothesis”), and restoring natural regimes could reverse this effect.  相似文献   

13.
This article describes the slight impact of Lysenkoism upon Polish botany. I begin with an account of the development of plant genetics in Poland, as well as the attitude of scientists and the Polish intelligentsia toward Marxist philosophy prior to the World War II. Next I provide a short history of the introduction and demise of Lysenkoism in Polish science, with a focus on events in botany, in context with key events in Polish science from 1939 to 1958. The article outlines the little effects of Lysenkoism upon botanists and their research, as well as how botanists for the most part rejected what was often termed the “new biology.” My paper shows that though Lysenko’s theories received political support, and were actively promoted by a small circle of scientists and Communist party activists, they were never accepted by most botanists. Once the political climate in Poland altered after the events of 1956, Lysenko’s theories were immediately abandoned.  相似文献   

14.
This review builds upon previous classifications of angiosperm female gametophytes but offers two new perspectives. Firstly, the course of development is compared to an algorithm: a predetermined set of rules that produces a mature female gametophyte. This analogy allows hypotheses to be developed as to what changes in the “developmental program” are responsible for variant forms of development. Secondly, the review recognizes that the four meiotic products of a megaspore mother cell have different genetic constitutions and may have conflicting interests. In most cases, only one member of a megaspore tetrad gives rise to a functional egg. This megaspore is called the germinal spore. The other members of the tetrad are called somatic spores. Somatic spores do not give rise to functional eggs and, therefore, cannot leave direct genetic descendants. Non-monosporic embryo sacs are genetic chimeras containing derivatives of more than one megaspore nucleus. Conflict may arise within such embryo sacs between the derivatives of the germinal megaspore nucleus and the derivatives of somatic megaspore nuclei. “Antipodal eggs” and chalazal “strike” are interpreted as evidence of this conflict. The behavior of somatic spores and their derivatives is often variable for different embryo sacs produced by the same sporophyte. This has created difficulties for existing classifications of embryo sac “types” because more than one type is sometimes recognized within a species. A new classification of developmental algorithms is presented that emphasizes the fate of the germinal spore and its derivatives.  相似文献   

15.
The deep and lasting changes to human behaviour that are required to address the global environmental crisis necessitate profound shifts in moral foundations. They amount to a change in what individuals and societies conceive of as progress. This imperative raises important questions about the justification, ends, and means of large-scale changes in people’s ethics. In this essay I will focus on the ends—the direction of moral change as prescribed by the goal of sustainable human flourishing. I shall present a meta-ethical critique of anthropocentrism and propose that only an ecocentric ethic can support the sustainable flourishing of humanity. This proposition does not necessarily contradict itself. My claim will be that the values subsumed under the broad concept of anthropocentrism are categorically counterproductive, informing an undesirable concept of “progress”. I support this claim with two lines of argument. On the one hand, the end values of anthropocentrism are shallow and the “flourishing of humanity” is ill-defined. The conceptual constraints of anthropocentrism itself preclude a more concise definition which would take into account the utter dependence of the flourishing of humanity on the health of ecological support structures. On the other hand, pursuing the values that inform the actions of anthropocentrists (which may be identical with the “flourishing of humanity”) leads to unintended and undesirable outcomes, even from the view of the anthropocentrist herself. Those problems are not encountered with an ecocentric ethic, and the conceptual steps necessary to adopt it are not insurmountable.  相似文献   

16.
Ali R  Zhao H 《EcoHealth》2008,5(2):159-166
This article briefly reviews environmental history in the “Sister Cities” of Wuhan, China and Pittsburgh, USA. Specifically, it analyzes key changes in air, water, land, and sustainability in each of the two cities in terms of both “driving forces” and of the actions of key stakeholders (policymakers, educators, industry/business, nongovernmental organizations [NGOs], and the public). It concludes by discussing prospects for synergies between the two cities in continuing to improve environmental health, and the implications of these ideas for other cities in both the “developing” and the “developed” world.  相似文献   

17.
Microfibril angle (MFA) is an important factor in determining the mechanical properties of individual cells and wood as a whole. While some studies have described the variation of MFA within trees, little work has been done on the extent to which MFA is influenced by climate, despite it being known to respond to climatic events. Year-to-year variation in MFA and ring width was measured at high resolution by SilviScan-3? on 30 dated Picea crassifolia trees growing in the northeastern Tibetan plateau. The climate signals registered in MFA and ring width were analyzed using dendroclimatological methods. The response function of MFA accounted for 67% of total variance, of which 60% was explained by climate elements. The response function of ring width explained 57% total variance, 37% of which was explained by climate variables. MFA significantly responded to July–August temperatures, and to precipitation in March, May and September. Over the period 1987–2009 temperatures generally increase and appeared to have a greater influence on MFA. A decrease in the strength of the relationship between MFA and ring width over the period 1987–2009 was also observed. MFA offers the potential to build robust climate proxies. The strong climate sensitivity of MFA to increasing temperature or the observed changes in the MFA–ring width relationship may contribute to resolving the “divergence problem” in temperature reconstructions. As far as we are aware, this study is the first to show a strong climate response in MFA and suggests that it might be a useful climate proxy.  相似文献   

18.
In the rapid “quench” kientics of myosin, the “initial phosphate burst” is the excess inorganic phosphate that is produced during the early time-course of ATP hydrolysis by myosin subfragment-1 (S-1) or HMM. In general, the existence of a Pi burst implies a rapid (i.e., generally an order of magnitude faster than the steady-state hydrolysis rate) lysis of the phospho-anhydride bond within the ATP molecule, followed by one or more slower steps that are rate limiting for the process. Thus, the presence of a Pi burst can provide an important clue to the mechanism of the reaction. However, in the case of actomyosin, this clue as long been the subject of controversy and misunderstanding. To measure the (initial) Pi burst, myosin S-1 (or HMM) is rapidly mixed with ATP and then the mixture is acid quenched after a specific time period. The medium produced contains free Pi generated from hydrolysis of the ATP. The quantitative measure of the phosphate generated in this way has always been significantly greater than that expected by steady-state “release” of Pi alone, and it is that very difference between this measured Pi after the quench and that amount of Pi expected to be released by steady-state considerations in that same time period that has been referred to as the “initial Pi burst”. Recent investigations of the kinetics of Pi release have used an entirely new method that directly measures the release of Pi from the enzyme-product complex. These studies have made reference to the properties of the “initial Pi burst” in the presence of actin, as well as to a new kinetic entity: the “burst of Pi release”, and have been often vague concerning the true nature of the initial Pi burst, as well as the properties of Pi release as predicted by the current models of the actin activation of the myosin ATPase activity. The purpose of the current article is to correct this oversight, to discuss the “burst” in some detail, and to display the kinetics predicted by the current models for the actin activation of myosin. Furthermore, predictions for the kinetics of the new “burst of Pi release” are discussed in terms of its ability to discriminate between the two current competing models for actin activation of the myosin ATPase activity.  相似文献   

19.
The objective of this study was to analyze the spatial and temporal dynamics of Chironomidae larvae assemblages in a subtropical mountain river basin of northwestern Argentina. We hypothesized that they would respond to (1) environmental changes along the altitudinal gradient in the Yungas forests; (2) environmental changes caused by spates (e.g., increased discharge or sediment transportation). We sampled five sites along an altitudinal gradient of ca. 1,500 m (from 680 to 2,170 m) during low-water and high-water period for 2 years. The Chironomidae larvae assemblages varied along the altitudinal gradient and between sampling periods based on an indicator species analyses and an ordination analyses (NMDS). The best indicator for high altitude sites was “Genus X” followed by Onconeura sp.2, “Genus 9”, “Genus 10”, and Rheotanytarsus sp.2; while Rheotanytarsus lamellatus, Oliveiriella sanjavieri, and Thienemanniella sp. were good indicators for low altitude sites. O. sanjavieri and R. lamellatus were the best indicators for high-water period. The most relevant environmental variables influencing their spatial and temporal distribution were altitude, water temperature, conductivity, and pH. This study is the first to analyze and describe in detail the spatial and temporal distribution of Chironomidae larvae assemblages in northwestern Argentina, and most of the taxa reported here are new records for the region.  相似文献   

20.
Atmospheric variables play a fundamental role in driving man-managed ecosystems and more specifically in agro-ecosystems, determining the quantity and quality of crop production. On the other hand, climate variability can be seen as the superimposition of gradual and abrupt changes. This paper is focused on European surface air temperature in the period 1951–2010. Analysis of this dataset identified breakpoints that define two homogeneous sub-periods: 1951–1987 and 1988–2010. Thermal resources for crops were analyzed adopting a “normal heat hours” approach. Computation highlighted a general increase in thermal resources in the European continent for crop groups II and III (C3 and C4 plants adapted to high or moderate temperatures), while a decline of thermal resources for crop group I (cold adapted C3) was highlighted in the Mediterranean area. The climate variability justifies a change in the potential latitudinal limits of different groups of crops, representing a fundamental step for crop adaptation to climate change.  相似文献   

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