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1.
The concept of refugee species provides a theoretical framework towards increasing the predictive power of the ‘declining population paradigm’ through identifying species which are expected to suffer from a declining population syndrome. Using a simple habitat model as a framework, refugee species are defined as those that can no longer access optimal habitat, but are confined to suboptimal habitats, with consequences of decreased fitness and density, and attendant conservation risks. Refugee species may be difficult to detect in the absence of information on prior habitat use and fitness and their observed ecology will be constrained by the habitat limits forced on them. Identification of refugee species, characterisation of pre‐refugee ecology and the restoration of such species to optimal habitat is critical to their successful conservation. The concept is showcased by addressing the conundrum of a large grazing bovid, the European bison Bison bonasus, being managed as a forest specialist, despite its evolutionary background, dental morphology, neonatal behaviour, diet and microhabitat selection being characteristic of a grazing species inhabiting open, grass‐rich habitats. It is hypothesized that a combination of increasing replacement of open steppe by forest cover after the last postglacial period and increasing human pressure forced bison into forests as a refuge habitat. This process was then reinforced through active management of bison in forests as managers committed themselves to the ‘bison as forest species’ paradigm. A research agenda to test this hypothesis using an experimental approach in the conservation management of European bison by introducing populations into diverse habitat types is suggested. 相似文献
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An important potential advantage of group-living that has been mostly neglected by life scientists is that individuals in animal groups may cope more effectively with unfamiliar situations. Social interaction can provide a solution to a cognitive problem that is not available to single individuals via two potential mechanisms: (i) individuals can aggregate information, thus augmenting their 'collective cognition', or (ii) interaction with conspecifics can allow individuals to follow specific 'leaders', those experts with information particularly relevant to the decision at hand. However, a-priori, theory-based expectations about which of these decision rules should be preferred are lacking. Using a set of simple models, we present theoretical conditions (involving group size, and diversity of individual information) under which groups should aggregate information, or follow an expert, when faced with a binary choice. We found that, in single-shot decisions, experts are almost always more accurate than the collective across a range of conditions. However, for repeated decisions - where individuals are able to consider the success of previous decision outcomes - the collective's aggregated information is almost always superior. The results improve our understanding of how social animals may process information and make decisions when accuracy is a key component of individual fitness, and provide a solid theoretical framework for future experimental tests where group size, diversity of individual information, and the repeatability of decisions can be measured and manipulated. 相似文献
3.
John Campbell 《Ethnic and racial studies》2013,36(4):670-690
This paper examines claims made about the role of ‘expert knowledge’ in analysing the language of individuals seeking asylum in the UK. I treat policy as a type of power and seek to understand how this policy uses the language of science to further the British government's stated interest to provide ‘secure borders’ and a ‘safe haven’ for refugees. I look at how the Home Office defines, shapes and implements the policy, and at how the policy has influenced judicial decisions. In short I unmask UKBA's claim that it relies upon expert, scientific knowledge to assess asylum claims. 相似文献
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Previous behavioral studies have shown that initial ownership influences individuals' fairness consideration and other-regarding behavior. However, it is not entirely clear whether initial ownership influences the brain activity when a recipient evaluates the fairness of asset distribution. In this study, we randomly assigned the bargaining property (monetary reward) to either the allocator or the recipient in the ultimatum game and let participants of the study, acting as recipients, receive either disadvantageous unequal, equal, or advantageous unequal offers from allocators while the event-related potentials (ERPs) were recorded. Behavioral results showed that participants were more likely to reject disadvantageous unequal and equal offers when they initially owned the property as compared to when they did not. The two types of unequal offers evoked more negative going ERPs (the MFN) than the equal offers in an early time window and the differences were not modulated by the initial ownership. In a late time window, however, the P300 responses to division schemes were affected not only by the type of unequal offers but also by whom the property was initially assigned to. These findings suggest that while the MFN may function as a general mechanism that evaluates whether the offer is consistent or inconsistent with the equity rule, the P300 is sensitive to top-down controlled processes, into which factors related to the allocation of attentional resources, including initial ownership and personal interests, come to play. 相似文献
6.
Ecotypic variation in the asymmetric Hawk-Dove game: When is Bourgeois an evolutionarily stable strategy? 总被引:1,自引:0,他引:1
Michael Mesterton-Gibbons 《Evolutionary ecology》1992,6(3):198-222
Summary This paper develops a mathematical model of an iterated, asymmetric Hawk-Dove game with the novel feature that not only are successive pairs of interactants — in the roles of owner and intruder contesting a site — drawn randomly from the population, but also the behaviour adopted at one interaction affects the role of a contestant in the next. Under the assumption that a site is essential for reproduction, the evolutionarily stable strategy (ESS) of the population is found to depend on the probability, w, that the game will continue for at least a further period (which is inversely related to predation risk), and five other parameters; two of them are measures of site scarcity, two are measures of fighting costs, and the last is a measure of resource holding potential (RHP). Among the four strategies — Hawk (H), Dove (D), Bourgeois (B) and anti-Bourgeois (X) — only D is incapable of being an ESS; and regions of parameter space are found in which the ESS can be only H, or only X, or only B; or either H or X; or either X or B; or either H or B; or any of the three. The scarcer the sites or the lower the costs of fighting, or the lower the value of w, the more likely it is that H is an ESS; the more abundant the sites or the higher the costs of fighting, or the higher the value of w, the more likely it is that X or B is an ESS. The different ESSs are interpreted as different ecotypes. The analysis suggests how a non-fighting population could evolve from a fighting population under decreasing risk of predation. If there were no RHP, or if RHP were low, then the ESS in the non-fighting population would be X; only if RHP were sufficiently high would the ESS be B, and the scarcer the sites, the higher the RHP would have to be. These conclusions support the thesis that if long-term territories are essential for reproduction and sites are scarce, then ownership is ruled out not only as an uncorrelated asymmetry for settling disputes in favour of owner, but also as a correlated asymmetry. 相似文献
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It has been anticipated that new, much more sensitive, next generation sequencing (NGS) techniques, using massively parallel
sequencing, will likely provide radical insights into the genetics of multifactorial diseases. While NGS has been used initially
to analyze individual human genomes, and has revealed considerable differences between healthy individuals, we have used NGS
to examine genetic variation within individuals, by sequencing tissues “in depth”, i.e., oversequencing many thousands of
times. Initial studies have revealed intra-tissue genetic heterogeneity, in the form of multiple variants of a single gene
that exist as distinct “majority and “minority” variants. This highly specialized form of somatic mosaicism has been found
within both cancer and normal tissues. If such genetic variation within individual tissues is widespread, it will need to
be considered as a significant factor in the ontogeny of many multifactorial diseases, including cancer. The discovery of
majority and minority gene variants and the resulting somatic cell heterogeneity in both normal and diseased tissues suggests
that selection, as opposed to mutation, might be the critical event in disease ontogeny. We, therefore, are proposing a hypothesis
to explain multifactorial disease ontogeny in which pre-existing multiple somatic gene variants, which may arise at a very
early stage of tissue development, are eventually selected due to changes in tissue microenvironments. 相似文献
10.
Sinéad O’Keeffe Stefan Majer Alberto Bezama Daniela Thrän 《The International Journal of Life Cycle Assessment》2016,21(6):885-902
Purpose
With many environmental burdens associated with bioenergy production occurring at the regional level, there is a need to produce more regional and spatially representative life cycle assessment of bioenergy systems. On the other hand, such assessments also need to account for the global and cumulative impacts along the full bioenergy life cycle in order to support effective regional policy measures and decision making. Therefore, the challenge is to find a balance. In other words, how should we define the regional context for bioenergy system assessments in order to complement life cycle thinking? The aim of this review is to answer this question by providing an overview of important considerations when assessing bioenergy systems in a regional and LCA context and how these two contexts intersect. It also aims to help guide and orientate LCA practitioners interested in including more regional aspects in their bioenergy studies. Until now, such a review which explores the integration of regional and life cycle contexts in relation to bioenergy systems and their products has not been done.Methods
As a first step, we define what we mean by the term region. We then look at the potential burdens relating to bioenergy systems and their relationship with the regional context. In a next step, we explore life cycle thinking and the intersection between the regional and LCA contexts by providing some examples from the literature. We then discuss the benefits and limitations of such regionally contextualized life cycle approaches in relation to bioenergy production systems and indeed other alternative biomass uses.Results and discussion
Three regional contexts were identified to help orientate life cycle thinking aiming to assess the regional and nonregional environmental implications of bioenergy production. These contexts were as follows: “within regional,” “regional and ROW,” and “regionalized.” The added value of implementing a regionally contextualized life cycle approach is the ability, therefore, to include greater regional and spatial details in the assessments of bioenergy production systems, without losing the links to the diversity of global supply chains. Thus, providing greater geographical and regional insight into how such potential burdens can be reduced or shifted burdens avoided or how associated regional production activities could be optimized to mitigate such burdens.Conclusions
The use of different regional contexts as proposed in this paper is not only useful to orientate life cycle thinking in relation to bioenergy systems but also for the assessment of alternative novel bio-based systems.11.
Sahar Sadeghi 《Ethnic and racial studies》2013,36(10):1613-1631
The 2015 refugee crisis is at the center of public and political discourse across Europe, especially among nations that have accepted refugees. Utilizing ethnographic fieldwork and 48 in-depth interviews conducted in 2011 and 2016 with Iranians in Hamburg, Germany, this paper considers how the refugee crisis impacts the racial boundaries between Germans and immigrant communities. It details how the crisis has made ethnic nationalism, Islamophobia, anti-foreigner prejudice and racism more pronounced and salient throughout Germany. The interviews demonstrate that this climate affects Iranians in several ways: they cite feeling more threat and stigma, as well as experiences of marginality, perpetual foreignness, and discrimination. This research contributes to sociological scholarship on migration and race by examining how critical international events influence and shape processes of racialization, identity and belonging, and social boundaries and hierarchies. 相似文献
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Tifeng Shan Shaojun Pang Xuemei Wang Jing Li Qianxi Li Li Su Xiaodong Li 《Journal of phycology》2020,56(6):1748-1753
Studies of quantitative trait loci based on genetic linkage maps require the establishment of a mapping population. Permanent mapping populations are more ideal than temporary ones because they can be used repeatedly. However, there has been no reported permanent sporophyte population of economically important kelp species. Based on the characteristics of the kelp life cycle, we proposed a method to establish, and then constructed experimentally, an “immortalized F2” (IF2) population of Undaria pinnatifida. Doubled-haploid “female” and “male” sporophytes were obtained through the parthenogenesis of a female gametophyte clone and the selfing of a “monoicous” gametophyte clone (originally male), respectively, and they were used as the parents. The F1 hybrid line was generated by crossing the female and male gametophytes derived from the respective female and male parents. Full-sibling F2 gametophyte clones, consisting of 260 females and 260 males, were established from an F1 hybrid sporophyte. Thirty-five females and 35 males were randomly selected and paired to give rise to an IF2 population containing 35 crossing lines. A parentage analysis using 10 microsatellite markers confirmed the accuracy of the IF2 population and indicated the feasibility of this method. This proposed method may be adapted for use in other kelp species, and thus, it will be useful for genetic studies of kelp. 相似文献
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《Dendrochronologia》2006,23(3):141-147
This paper illustrates the use of tree-ring indices as an indicator of economic stress. In the 19th century the rural economy in the Puna of Jujuy, Northwestern Argentina was based on livestock (llamas and sheep), and was heavily dependant on the availability of pasture and water in this arid landscape. In the absence of traditional indicators of socioeconomic stress, we used tree-ring indices from moisture sensitive trees (Juglans australis Griseb. and Polylepis tarapacana Phil.) as a proxy for droughts and their related economic stresses. Examining the relationship between population mortality and ring-width indices allows inferences to be drawn about the relative importance of environmental and sociopolitical factors in determining mortality patterns that contributed to the depopulation of this area in the late 19th century. 相似文献
14.
Alison G. Boyer Helen F. James Storrs L. Olson Jack A. Grant-Mackie 《Biodiversity and Conservation》2010,19(11):3207-3224
Through the continuing accumulation of fossil evidence, it is clear that first human arrival on islands around the world was
linked to a rise in the extinction rate for vertebrates. Bones in human-era fossil sites can also reveal changes in the composition
and structure of ecological communities due to human environmental impacts. New Caledonia is a large and biogeographically
distinct island in the southwest Pacific and is considered a critical priority for biodiversity conservation. We examined
fossil birds from the Mé Auré Cave site (WMD007), located in lowland dry forest on the west coast of New Caledonia. Accumulation
of bird skeletal material in the cave was primarily through deposition in barn owl (Tyto alba) pellets. The site recorded the island-wide extinction of two species and extirpation of at least two other species from
the lowlands in the past 1200 years. Species richness of birds in the stratigraphic deposit was quite high, reflecting the
catholic diet of barn owls on islands, and many species have continued to persist near the site despite loss and degradation
of the dry forest. However, we found substantial turnover in relative abundance of species in the cave deposit, with edge
and open country birds becoming more common through time. These changes may reflect the severe reduction of dry forest habitat
during the colonial period. This work provides a temporal record of avifaunal and environmental change in the threatened dry
forest habitat that should be particularly informative for ongoing conservation and restoration efforts. 相似文献
15.
Currently, the global annual flux of methane (CH4) to the atmosphere is fairly well constrained at ca. 645 Tg CH4 year?1. However, the relative magnitudes of the fluxes generated from different natural (e.g. wetlands, deep seepage, hydrates, ocean sediments) and anthropogenic sources remain poorly resolved. Of the identified natural sources, the contribution of vegetation to the global methane budget is arguably the least well understood. Historically, reviews of the contribution of vegetation to the global methane flux have focused on the role of plants as conduits for soil-borne methane emissions from wetlands, or the aerobic production of methane within plant tissues. Many recent global budgets only include the latter pathway (aerobic methane production) in estimating the importance of terrestrial vegetation to atmospheric CH4 flux. However, recent experimental evidence suggests several novel pathways through which vegetation can contribute to the flux of this globally important, trace greenhouse gas (GHG), such as plant cisterns that act as cryptic wetlands, heartwood rot in trees, the degradation of coarse woody debris and litter, or methane transport through herbaceous and woody plants. Herein, we synthesize the existing literature to provide a comprehensive estimate of the role of modern vegetation in the global methane budget. This first, albeit uncertain, estimate indicates that vegetation may represent up to 22 % of the annual flux of methane to the atmosphere, contributing ca. 32–143 Tg CH4 year?1 to the global flux of this important trace GHG. Overall, our findings emphasize the need to better resolve the role of vegetation in the biogeochemical cycling of methane as an important component of closing the gap in the global methane budget. 相似文献
16.
Howard McEwen D. L. McNeil S. B. Thorson W. Mary Longmore Maria G. Castelli 《CMAJ》1963,89(22):1133-1137
A survey of the management of diabetes mellitus in an “open” hospital, Calgary General Hospital, was conducted in 1954 by reviewing the records of 100 consecutive diabetic admissions and by interviewing medical, nursing and dietetic staff members. The diabetic state was controlled satisfactorily by diet and insulin, but early diabetic complications and patient education tended to be overlooked by physicians. Diabetic management from the nursing, administrative and dietetic standpoints was considered to be inefficient, unpredictable and incomplete.In 1955 a comprehensive diabetic service was instituted which co-ordinated the activities of medical, nursing and dietetic staffs and provided for patient education. A repeat survey conducted in 1961, in which the records of 87 consecutive diabetic admissions were reviewed, showed marked improvement in all areas of diabetic patient care.Objections to voluntary conformity by staff members were surprisingly absent. The institution of a diabetic service is recommended for all hospitals as a means of improving diabetic care. 相似文献
17.
Streptomycetes are antibiotic-producing filamentous microorganisms that have a mycelial life style. In many ways streptomycetes are the odd ones out in terms of cell division. While the basic components of the cell division machinery are similar to those found in rod-shaped bacteria such as Escherichia coli and Bacillus subtilis, many aspects of the control of cell division and its co-ordination with chromosome segregation are remarkably different. The rather astonishing fact that cell division is not essential for growth makes these bacteria unique. The fundamental difference between the cross-walls produced during normal growth and sporulation septa formed in aerial hyphae, and the role of the divisome in their formation are discussed. We then take a closer look at the way septum site localization is regulated in the long and multinucleoid Streptomyces hyphae, with particular focus on actinomycete-specific proteins and the role of nucleoid segregation and condensation. 相似文献
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Rodolfo Alejandro Hernández Corchado 《Dialectical Anthropology》2018,42(2):179-191
Since the late 1980s, indigenous Mixtecos of the Montaña region, in the southern state of Guerrero, Mexico, have become new members of the Mexican migrant working class in New York City (NYC). This article examines the contemporary history of proletarianization via migration of the Mixtecos of the Montaña. It shows to what extent the region became a supplier of migrant labor, and how its inhabitants transitioned from peasants and semi-proletarians of Mexico’s northwest agribusinesses to transnational migrant proletarians, as a result of major regional transformations related to state violence and drug cartel penetration. Indigenous Mixtecos have endured social inequality, racism, and state violence from post-revolutionary to contemporary neoliberal governments in Guerrero. Before their migration to NYC, they have gone through different rounds of proletarianization which differ from the Mexican mestizo migrant flow. The article aims to contribute to unravel such particularities, which have been subsumed as part of a homogeneous pattern in the history of Mexican migration and proletarianization in NYC.Based on ethnographic research conducted for my doctoral dissertation (2014) and using oral history, the article traces, through the life story of a Mixteco migrant worker, the different rounds of dispossession in the history of proletarianization of Mixteco indigenous migrants from the Montaña. 相似文献
20.
A marine sea slug, Elysia chlorotica, has acquired the ability to carry out photosynthesis as a result of forming an intracellular symbiotic association with chloroplasts of the chromophytic alga, Vaucheria litorea. The symbiont chloroplasts (kleptoplasts) are functional, i.e. they evolve oxygen and fix CO2 and actively transcribe and translate proteins for several months in the sea slug cytosol. Considering the dependency of plastid function on nuclear genes, the level of kleptoplast activity observed in the animal cell is quite remarkable. Possible factors contributing to this long-lasting functional association that are considered here include: the presence of an algal nuclear genome in the sea slug, autonomous chloroplasts, unusual chloroplast/protein stability, re-directing of animal proteins to the kleptoplast, and lateral gene transfer. Based on our current understanding, the acquisition and incorporation of intact algal plastids by E. chlorotica is aided by the robustness of the plastids and the long-term functional activity of the kleptoplasts appears to be supported by both plastid and protein stability and contributions from the sea slug. 相似文献