抗原变异可使得多种致病微生物易于逃避宿主免疫应答。表达在感染红细胞表面的恶性疟原虫红细胞表面蛋白1（PfPMP1）与感染红细胞、内皮细胞、树突状细胞以及胎盘的单个或多个受体作用，在黏附及免疫逃避中起关键的作用。每个单倍体基因组var基因家族编码约60种成员，通过启动转录不同的var基因变异体为抗原变异提供了分子基础。

疟原虫var基因转换速率变化导致抗原变异[英]／Paul H, Robert P, Christodoulou Z, et al//Proc Natl Acad Sci U S A

Preface to the Princeton Landmarks in Biology Edition vii Preface xi Symbols Used xiii 1. The Importance of Islands 3 2. Area and Number of Speicies 8 3. Further Explanations of the Area-Diversity Pattern 19 4. The Strategy of Colonization 68 5. Invasibility and the Variable Niche 94 6. Stepping Stones and Biotic Exchange 123 7. Evolutionary Changes Following Colonization 145 8. Prospect 181 Glossary 185 References 193 Index 201

The Theory of Island Biogeography

Hypothesis-testing methods for multivariate data are needed to make rigorous probability statements about the effects of factors and their interactions in experiments. Analysis of variance is particularly powerful for the analysis of univariate data. The traditional multivariate analogues, however, are too stringent in their assumptions for most ecological multivariate data sets. Non-parametric methods, based on permutation tests, are preferable. This paper describes a new non-parametric method for multivariate analysis of variance, after McArdle and Anderson (in press). It is given here, with several applications in ecology, to provide an alternative and perhaps more intuitive formulation for ANOVA (based on sums of squared distances) to complement the description pro- vided by McArdle and Anderson (in press) for the analysis of any linear model. It is an improvement on previous non-parametric methods because it allows a direct additive partitioning of variation for complex models. It does this while maintaining the flexibility and lack of formal assumptions of other non-parametric methods. The test- statistic is a multivariate analogue to Fisher's F-ratio and is calculated directly from any symmetric distance or dissimilarity matrix. P-values are then obtained using permutations. Some examples of the method are given for tests involving several factors, including factorial and hierarchical (nested) designs and tests of interactions.

/pdf/a-new-method-for-non-parametric-multivariate-analysis-of-2zyb4px7ty.pdf

A new method for non-parametric multivariate analysis of variance

Land use has generally been considered a local environmental issue, but it is becoming a force of global importance. Worldwide changes to forests, farmlands, waterways, and air are being driven by the need to provide food, fiber, water, and shelter to more than six billion people. Global croplands, pastures, plantations, and urban areas have expanded in recent decades, accompanied by large increases in energy, water, and fertilizer consumption, along with considerable losses of biodiversity. Such changes in land use have enabled humans to appropriate an increasing share of the planet’s resources, but they also potentially undermine the capacity of ecosystems to sustain food production, maintain freshwater and forest resources, regulate climate and air quality, and ameliorate infectious diseases. We face the challenge of managing trade-offs between immediate human needs and maintaining the capacity of the biosphere to provide goods and services in the long term.

/pdf/global-consequences-of-land-use-map7a6ziel.pdf

Global Consequences of Land Use

世界経済・社会統計 = World development indicators

Net ecosystem production (NEP) is the difference between gross primary production (GPP) and community respiration (R). We estimated in situ NEP using three independent approaches (net CO2 gas flux, net O 2 gas flux, and continuous diel O2 measurements) over a 4‐7 yr period in a series of small lakes in which food webs were manipulated and nutrient loadings were experimentally varied. In the absence of manipulation, these lakes were net heterotrophic according to all three approaches. NEP (NEP 5 GPP-R) was consistently negative and averaged 235.5 6 3.7 (standard error) mmol C m 22 d 21 . Nutrient enrichment, in the absence of strong planktivory, tended to cause increases in estimates of both GPP and R (estimated from the continuous O2 data) but resulted in little change in the GPP/R ratio, which remained ,1, or NEP, which remained negative. When planktivorous fish dominated the food web, large zooplankton were rare and nutrient enrichment produced positive values of NEP by all three methods. Among lakes and years, daily values of NEP ranged from 2241 to 1175 mmol m 22 d 21 ; mean seasonal NEP was positive only under a combination of high nutrient loading and a planktivore-dominated food web. Community R is significantly subsidized by allochthonous sources of organic matter in these lakes. Combining all lakes and years, we estimate that ;26 mmol C m 22 d 21 of allochthonous origin is respired on average. This respiration of allochthonous organic matter represents 13 to 43% of total R, and this fraction declines with increasing GPP.

https://aslopubs.onlinelibrary.wiley.com/doi/pdf/10.4319/lo.2000.45.8.1718

Persistence of net heterotrophy in lakes during nutrient addition and food web manipulations

The purpose of this paper is to provide ecologists and resource managers with a sense of where the economic science of ecosystem valuation has come from and where it might go in the future. To accomplish this, the paper provides a comprehensive synthesis of peer-reviewed economic data on surface freshwater ecosystems in the United States and examines major accomplishments and gaps in the literature. Economic value has been assigned to nonmarket goods and services provided by surface freshwater systems in the United States by 30 published, refereed articles in the scientific literature from 1971 to 1997. These studies have used variations of three approaches for a quantitative assessment of economic value: travel cost methods, hedonic pricing methods, and contingent valuation methods. To determine the economic value of nonmarket ecosystem goods and services, each method focuses on a different aspect of social benefit associated with lakes, streams, rivers, and wetlands. Valuation methodologies work from different underlying assumptions while possessing unique limitations and uncertainties. Dollar benefit estimates derived for nonmarket freshwater ecosystem goods and services from these studies tend to be specific to a particular method, ecosystem, and socioeconomic circumstance. Creative interdisci- plinary research is needed on the quantitative measurement of surface freshwater ecosystem goods and service values, the relation of these values to key limnological variates, and communication of limnological insights to the public and social scientists in ways that facilitate and improve future management and research.

/pdf/economic-valuation-of-freshwater-ecosystem-services-in-the-2gys7m8xm2.pdf

Economic valuation of freshwater ecosystem services in the united states: 1971-1997

Freshwater ecosystem services.

Adaptive capacity is the ability of a living system, such as a social-ecological system, to adjust responses to changing internal demands and external drivers. Although adaptive capacity is a frequent topic of study in the resilience literature, there are few formal models. This paper introduces such a model and uses it to explore adaptive capacity by contrast with the opposite condition, or traps. In a social- ecological rigidity trap, strong self-reinforcing controls prevent the flexibility needed for adaptation. In the model, too much control erodes adaptive capacity and thereby increases the risk of catastrophic breakdown. In a social-ecological poverty trap, loose connections prevent the mobilization of ideas and resources to solve problems. In the model, too little control impedes the focus needed for adaptation. Fluctuations of internal demand or external shocks generate pulses of adaptive capacity, which may gain traction and pull the system out of the poverty trap. The model suggests some general properties of traps in social-ecological systems. It is general and flexible, so it can be used as a building block in more specific and detailed models of adaptive capacity for a particular region.

/pdf/adaptive-capacity-and-traps-1yfe3iwqxr.pdf

Adaptive Capacity and Traps

Climate change, biodiversity loss, antibiotic resistance, and other global challenges pose major collective action problems: A group benefits from a certain action, but no individual has sufficient incentive to act alone. Formal institutions, e.g., laws and treaties, have helped address issues like ozone depletion, lead pollution, and acid rain. However, formal institutions are not always able to enforce collectively desirable outcomes. In such cases, informal institutions, such as social norms, can be important. If conditions are right, policy can support social norm changes, helping address even global problems. To judge when this is realistic, and what role policy can play, we discuss three crucial questions: Is a tipping point likely to exist, such that vicious cycles of socially damaging behavior can potentially be turned into virtuous ones? Can policy create tipping points where none exist? Can policy push the system past the tipping point?

https://science.sciencemag.org/content/sci/354/6308/42.full.pdf

Stephen R. Carpenter

Papers

Persistence of net heterotrophy in lakes during nutrient addition and food web manipulations

Economic valuation of freshwater ecosystem services in the united states: 1971-1997

Freshwater ecosystem services.

Adaptive Capacity and Traps

Social norms as solutions