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Accurate understanding of population connectivity is important to conservation because dispersal can play an important role in population dynamics, microevolution, and assessments of extirpation risk and population rescue. Genetic methods are increasingly used to infer population connectivity because advances in technology have made them more advantageous (e.g., cost effective) relative to ecological methods. Given the reductions in wildlife population connectivity since the Industrial Revolution and more recent drastic reductions from habitat loss, it is important to know the accuracy of and biases in genetic connectivity estimators when connectivity has declined recently. Using simulated data, we investigated the accuracy and bias of 2 common estimators of migration (movement of individuals among populations) rate. We focused on the timing of the connectivity change and the magnitude of that change on the estimates of migration by using a coalescent‐based method (Migrate‐n) and a disequilibrium‐based method (BayesAss). Contrary to expectations, when historically high connectivity had declined recently: (i) both methods over‐estimated recent migration rates; (ii) the coalescent‐based method (Migrate‐n) provided better estimates of recent migration rate than the disequilibrium‐based method (BayesAss); (iii) the coalescent‐based method did not accurately reflect long‐term genetic connectivity. Overall, our results highlight the problems with comparing coalescent and disequilibrium estimates to make inferences about the effects of recent landscape change on genetic connectivity among populations. We found that contrasting these 2 estimates to make inferences about genetic‐connectivity changes over time could lead to inaccurate conclusions.  相似文献   
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Jesse McEntee 《Local Environment》2013,18(9-10):785-803
The increasingly popular local food movement in the US has experienced wide-scale buy-in on behalf of the general public as well as in academic arenas. However, there have been recent efforts to critique this movement, typically for being inequitable and unfairly geared towards those with above-average financial means. In this article, I examine local food efforts and present a new conceptualisation of food localism. While geographically localised food consumption activities are taking place, some have ideological labels attached to them, whereas others do not. What I have termed contemporary and traditional localisms exist in the same physical but different social space. The contemporary local is represented by current local food initiatives and corresponding aspirations to support local farmers and to promote sustainability through local purchasing behaviour. The traditional local, on the other hand, is similar in that it represents food growing activities that are in close geographical proximity to consumption, but lacks the motivation associated with the contemporary local's programmatic literature; instead, it is guided by a motivation to obtain fresh and affordable food. I substantiate the contemporary/traditional localism framework with qualitative fieldwork findings from Grafton County, New Hampshire, USA, and describe the practical as well as conceptual implications of this framework.  相似文献   
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IntroductionTheword“environment”nowbecomesacatchwordinChina,buttheterm“environmentalawareness(EA)”isstillnotinthesameposition.ThisisthereasonwhyItrytomakeabriefinquiryinthispaperabouttherelationshipbetweentheEAandChina○ssociety.EAisanunderstandingofv…  相似文献   
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在领导当代中国发展的过程中,邓小平把发展问题提到了前所未有的高度,明确提出了“发展才是硬道理”的科学论断,全面论述了发展问题的极端重要性.他始终强调:发展应该是有科学理论指导的,必须毫不动摇地坚持马克思主义在当代中国发展中的指导地位;发展是有性质和方向的,中国的发展必须坚持社会主义的制度属性、发展方向和根本原则;发展是必须坚持科学方法的,要把重点论和全面论、阶段论和持续性统一起来,贯彻统筹兼顾的原则,实现全面、持续、稳定、协调的发展.邓小平的科学发展思想有着重大的理论意义和启示价值:必须从战略高度看待发展问题,真正把发展看作是执政兴国的第一要务、科学发展观的第一要义;必须始终牢固坚持马克思主义的指导地位,反对指导思想的多元化;必须科学理解发展的性质和方向,破除“发展主义的意识形态”;必须坚持统筹兼顾的方法论原则,按照全面、协调、可持续的要求推动当代中国的发展.  相似文献   
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Abstract: Effective population size (Ne) determines the strength of genetic drift in a population and has long been recognized as an important parameter for evaluating conservation status and threats to genetic health of populations. Specifically, an estimate of Ne is crucial to management because it integrates genetic effects with the life history of the species, allowing for predictions of a population's current and future viability. Nevertheless, compared with ecological and demographic parameters, Ne has had limited influence on species management, beyond its application in very small populations. Recent developments have substantially improved Ne estimation; however, some obstacles remain for the practical application of Ne estimates. For example, the need to define the spatial and temporal scale of measurement makes the concept complex and sometimes difficult to interpret. We reviewed approaches to estimation of Ne over both long‐term and contemporary time frames, clarifying their interpretations with respect to local populations and the global metapopulation. We describe multiple experimental factors affecting robustness of contemporary Ne estimates and suggest that different sampling designs can be combined to compare largely independent measures of Ne for improved confidence in the result. Large populations with moderate gene flow pose the greatest challenges to robust estimation of contemporary Ne and require careful consideration of sampling and analysis to minimize estimator bias. We emphasize the practical utility of estimating Ne by highlighting its relevance to the adaptive potential of a population and describing applications in management of marine populations, where the focus is not always on critically endangered populations. Two cases discussed include the mechanisms generating Ne estimates many orders of magnitude lower than census N in harvested marine fishes and the predicted reduction in Ne from hatchery‐based population supplementation.  相似文献   
6.
Wild game management for hunting in Western society has become increasingly complex as stakeholders have multiplied and as ‘sustainability’ influences the contemporary debate. This paper questions whether the current legal framework for game management, which has evolved from early European civilisations to focus on ‘hunting rights’, is relevant to regulate the contemporary environmental, social and economic dimensions of wild game and their management. Employing a narrative analysis to focus on deer, the study identifies key legislative tenets and highlights the pertinence of historical laws to contemporary conflicts. The analysis suggests that current legislation is increasingly divergent from contemporary trends and has created inertia with respect to sustainable deer management. The paper offers four options to redress this: state intervention; voluntary collaboration; financial incentives; and establishing a legal responsibility for management. It is concluded that significant innovation is required in one or more of these four areas to facilitate the contemporary sustainable management of wild deer in Britain.  相似文献   
7.
先秦儒家生态文明思想的内容主要包括生态精神文明和生态制度文明两个部分;其特征有三:轻视物质文明,产生于落后生产力时期的农业文明,集中于对第一大历史形态的思考。以此形成对当代生态文明建设的三点重要启示。  相似文献   
8.
阐述了当代第三条道路理论的形成背景及发展状况,并对第三条道路经济发展观的具体内容作了客观地阐述,然后就第三条道路经济观对当代中国经济发展的借鉴意义进行了有益的探讨.参13.  相似文献   
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Plant translocation is a useful tool for implementing assisted gene flow in recovery plans of critically endangered plant species. Although it helps to restore genetically viable populations, it is not devoid of genetic risks, such as poor adaptation of transplants and outbreeding depression in the hybrid progeny, which may have negative consequences in terms of demographic growth and plant fitness. Hence, a follow-up genetic monitoring should evaluate whether the translocated populations are genetically viable and self-sustaining in the short and long term. The causes of failure to adjust management responses also need to be identified. Molecular markers and fitness-related quantitative traits can be used to determine whether a plant translocation enhanced genetic diversity, increased fitness, and improved the probability of long-term survival. We devised guidelines and illustrated them with studies from the literature to help practitioners determine the appropriate genetic survey methods so that management practices can better integrate evolutionary processes. These guidelines include methods for sampling and for assessing changes in genetic diversity and differentiation, contemporary gene flow, mode of local recruitment, admixture level, the effects of genetic rescue, inbreeding or outbreeding depression and local adaptation on plant fitness, and long-term genetic changes.  相似文献   
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