Estimation of Copper In‐use Stocks in Nanjing,China

Copper (Cu) is an essential but supply‐restricted resource in China. Characterization of in‐use stocks can provide useful instruction for the future recycling of copper. This article attempts to estimate copper in‐use stocks in a Chinese city. To this purpose, an extensive bottom‐up estimate of copper stocks in use in Nanjing in the year 2009 was conducted. The results are a total stock estimate of 295 gigagrams (Gg) of copper or 46.9 kilograms (kg) of copper per capita for 2009. Infrastructure, equipment, and buildings contain 42.0%, 26.1%, and 28.1% of the total stock, respectively, indicating that these three categories are principal potential reservoirs of a secondary copper resource. The copper in transportation amounts to only about 3.7% of the total amount. The per capita stock was compared with similar studies carried out in other regions of the world, and the results show that the Nanjing level is significantly lower than developed countries. On the whole, our results show that electric power transmission and distribution systems, buildings, household durables, and industrial equipment are the four largest potential reservoirs of copper scrap.     

Optimal surveillance and eradication of invasive species in heterogeneous landscapes

Cost-effective surveillance strategies are needed for efficient responses to biological invasions and must account for the trade-offs between surveillance effort and management costs. Less surveillance may allow greater population growth and spread prior to detection, thereby increasing the costs of damages and control. In addition, surveillance strategies are usually applied in environments under continual invasion pressure where the number, size and location of established populations are unknown prior to detection. We develop a novel modeling framework that accounts for these features of the decision and invasion environment and determines the long term sampling effort that minimises the total expected costs of new invasions. The optimal solution depends on population establishment and growth rates, sample sensitivity, and sample, eradication, and damage costs. We demonstrate how to optimise surveillance systems under budgetary constraints and find that accounting for spatial heterogeneity in sampling costs and establishment rates can greatly reduce management costs.     

The value of coordinated management of interacting ecosystem services

Coordinating decisions and actions among interacting sectors is a critical component of ecosystem-based management, but uncertainty about coordinated management's effects is compromising its perceived value and use. We constructed an analytical framework for explicitly calculating how coordination affects management decisions, ecosystem state and the provision of ecosystem services in relation to ecosystem dynamics and socio-economic objectives. The central insight is that the appropriate comparison strategy to optimal coordinated management is optimal uncoordinated management, which can be identified at the game theoretic Nash equilibrium. Using this insight we can calculate coordination's effects in relation to uncoordinated management and other reference scenarios. To illustrate how this framework can help identify ecosystem and socio-economic conditions under which coordination is most influential and valuable, we applied it to a heuristic case study and a simulation model for the California Current Marine Ecosystem. Results indicate that coordinated management can more than double an ecosystem's societal value, especially when sectors can effectively manipulate resources that interact strongly. However, societal gains from coordination will need to be reconciled with observations that it also leads to strategic simplification of the ecological food web, and generates both positive and negative impacts on individual sectors and non-target species.     

Maximising return on conservation investment in the conterminous USA

Efficient conservation planning requires knowledge about conservation targets, threats to those targets, costs of conservation and the marginal return to additional conservation efforts. Systematic conservation planning typically only takes a small piece of this complex puzzle into account. Here, we use a return‐on‐investment (ROI) approach to prioritise lands for conservation at the county level in the conterminous USA. Our approach accounts for species richness, county area, the proportion of species' ranges already protected, the threat of land conversion and land costs. Areas selected by a complementarity‐based greedy heuristic using our full ROI approach provided greater averted species losses per dollar spent compared with areas selected by heuristics accounting for richness alone or richness and cost, and avoided acquiring lands not threatened with conversion. In contrast to traditional prioritisation approaches, our results highlight conservation bargains, opportunities to avert the threat of development and places where conservation efforts are currently lacking.     

Where do adaptive shifts occur during invasion? A multidisciplinary approach to unravelling cold adaptation in a tropical ant species invading the Mediterranean area

Evolution may improve the invasiveness of populations, but it often remains unclear whether key adaptation events occur after introduction into the recipient habitat (i.e. post‐introduction adaptation scenario), or before introduction within the native range (i.e. prior‐adaptation scenario) or at a primary site of invasion (i.e. bridgehead scenario). We used a multidisciplinary approach to determine which of these three scenarios underlies the invasion of the tropical ant Wasmannia auropunctata in a Mediterranean region (i.e. Israel). Species distribution models (SDM), phylogeographical analyses at a broad geographical scale and laboratory experiments on appropriate native and invasive populations indicated that Israeli populations followed an invasion scenario in which adaptation to cold occurred at the southern limit of the native range before dispersal to Israel. We discuss the usefulness of combining SDM, genetic and experimental approaches for unambiguous determination of eco‐evolutionary invasion scenarios.     

Precision of host sanctions in the fig tree–fig wasp mutualism: consequences for uncooperative symbionts

Host sanctions that reduce the relative fitness of uncooperative symbionts provide a mechanism that can limit cheating and thus stabilise mutualisms over evolutionary timescales. Sanctions have been demonstrated empirically in several mutualisms. However, if multiple individual symbionts interact with each host, the precision with which individual cheating symbionts are targeted by host sanctions is critical to their short‐ and long‐term effectiveness. No previous empirical study has directly addressed this issue. Here, we report the precision of host sanctions in the mutualism between fig trees and their pollinating wasps. Using field experiments and molecular parentage analyses, we show that sanctions in Ficus nymphaeifolia act at the level of entire figs (syconia), not at the level of the individual flowers within. Such fig‐level sanctions allow uncooperative wasps, which do not bring pollen, to avoid sanctions in figs to which other wasps bring pollen. We discuss the relevance of sanction precision to other mutualisms.     

Why are defensive toxins so variable? An evolutionary perspective

Defensive toxins are widely used by animals, plants and micro-organisms to deter natural enemies. An important characteristic of such defences is diversity both in the quantity of toxins and the profile of specific defensive chemicals present. Here we evaluate evolutionary and ecological explanations for the persistence of toxin diversity within prey populations, drawing together a range of explanations from the literature, and adding new hypotheses. We consider toxin diversity in three ways: (1) the absence of toxicity in a proportion of individuals in an otherwise toxic prey population (automimicry); (2) broad variation in quantities of toxin within individuals in the same population; (3) variation in the chemical constituents of chemical defence. For each of these phenomena we identify alternative evolutionary explanations for the persistence of variation. One important general explanation is diversifying (frequency- or density-dependent) selection in which either costs of toxicity increase or their benefits decrease with increases in the absolute or relative abundance of toxicity in a prey population. A second major class of explanation is that variation in toxicity profiles is itself nonadaptive. One application of this explanation requires that predator behaviour is not affected by variation in levels or profiles of chemical defence within a prey population, and that there are no cost differences between different quantities or forms of toxins found within a population. Finally, the ecology and life history of the animal may enable some general predictions about toxin variation. For example, in animals which only gain their toxins in their immature forms (e.g. caterpillars on host plants) we may expect a decline in toxicity during adult life (or at least no change). By contrast, when toxins are also acquired during the adult form, we may for example expect the converse, in which young adults have less time to acquire toxicity than older adults. One major conclusion that we draw is that there are good reasons to consider within-species variation in defensive toxins as more than mere ecological noise. Rather there are a number of compelling evolutionary hypotheses which can explain and predict variation in prey toxicity.     

用模块化分子元件调控和编程生物系统

合成生物学的目标包括“通过合成来理解生命”以及用现代工程学方法设计合成复杂生物系统．其工程学目标的实现依赖于可集成、可调控、可重用、功能多样的蛋白质、RNA、DNA等基本分子元件．以分子机制为基础,合理设计与实验室进化相结合,改造和创建生物分子的相互作用特异性、调控方式、定量活性等,是实现生物系统人工调控与编程的重要策略,同时为自下而上设计合成日益复杂的人工生物系统奠定基础．     

茉莉酸甲酯和虫害诱导棉花对棉蚜及其天敌选择行为的影响

以棉蚜及其天敌十一星瓢虫、叶色草蛉为对象,通过Y型嗅觉仪测定了3种昆虫对不同味源物的行为反应。结果表明,健康棉株叶片对棉蚜的吸引作用与虫害棉叶和茉莉酸甲酯(MeJA)处理棉叶未存在显著性差异;十一星瓢虫和叶色草蛉对虫害棉叶的选择性是健康棉叶的2.7和2.2倍(P<0.001),对MeJA处理棉叶的选择性明显高于健康叶片(P<0.001),其中0.02μmol.mL-1处理的棉叶对天敌的吸引力最强,单一的MeJA对十一星瓢虫和叶色草蛉也具有吸引作用。     

海草生物活性成分的研究进展

本文综述了海草中生物活性成分的研究进展,其化学成分类型主要是苯酚类、黄酮类和二萜类化合物,生物活性主要包括抗菌、抗氧化、抗病毒、细胞毒性、抑制海藻生长和抗污损等.