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.

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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

Two examples, blue-green algal blooms and the fish-driven trophic cascade, illustrate important consequences of time scale dependency in lakes. Blue-green algae and fish populations are notably variable components of lake communities. The timing of colonization of the water column by blue-green algae, relative to population oscillations of grazers and other algal groups, determines the magnitude of subsequent blooms. Variability in colonization acts jointly with dynamic variability in herbivory to produce large fluctuations in blue-green algal concentration at time scales of weeks to years. Fishes exhibit high interannual variance in recruitment. Episodes of high recruitment cascade through lake food webs, inducing fluctuations in lower trophic levels at time scales of years to decades. Fishes, through their effects on herbivores, contribute to variability in blue-green algal blooms. Blue-green algae and fishes are foci of lake management, so analyses of their variable and scale-dependent interactions are important for applied limnology. Theories and models that address nonequilibrial dynamics, analyses of effects of time scale on correlations and experiments, and improved paleolimnological capabilities will yield valuable progress on temporal scale issues in limnology and ecology.

Temporal variance in lake communities: blue-green algae and the trophic cascade

Successful management of natural resources requires local action that adapts to larger‐scale environmental changes in order to maintain populations within the safe operating space (SOS) of acceptable conditions. Here, we identify the boundaries of the SOS for a managed freshwater fishery in the first empirical test of the SOS concept applied to management of harvested resources. Walleye (Sander vitreus) are popular sport fish with declining populations in many North American lakes, and understanding the causes of and responding to these changes is a high priority for fisheries management. We evaluated the role of changing water clarity and temperature in the decline of a high‐profile walleye population in Mille Lacs, Minnesota, USA, and estimated safe harvest under changing conditions from 1987 to 2017. Thermal–optical habitat area (TOHA)—the proportion of lake area in which the optimal thermal and optical conditions for walleye overlap—was estimated using a thermodynamic simulation model of daily water temperatures and light conditions. We then used a SOS model to analyze how walleye carrying capacity and safe harvest relate to walleye thermal–optical habitat. Thermal–optical habitat area varied annually and declined over time due to increased water clarity, and maximum safe harvest estimated by the SOS model varied by nearly an order of magnitude. Maximum safe harvest levels of walleye declined with declining TOHA. Walleye harvest exceeded safe harvest estimated by the SOS model in 16 out of the 30 yr of our dataset, and walleye abundance declined following 14 of those years, suggesting that walleye harvest should be managed to accommodate changing habitat conditions. By quantifying harvest trade‐offs associated with loss of walleye habitat, this study provides a framework for managing walleye in the context of ecosystem change.

Water clarity and temperature effects on walleye safe harvest: an empirical test of the safe operating space concept

Airborne inputs of terrestrial particulate organic carbon (TPOC) were measured during summ- er stratification for an oligotrophic north temperate lake located in a forested watershed. These inputs were episodic and associated with wind and rain events. The rate of deposition decreased exponentially with distance from shore. Yet, about 55 % of the total airborne TPOC input occurred more than 12 m from shore on this 25.8 ha lake. Of total deposition, 39 % was less than 153 mm in diameter - a size fraction not commonly measured in prior studies. Average air- borne deposition was 5 mg C m -2 d -1 , which is consistent with measurements from other lakes and equivalent to about 1.1 % of daily net primary production in our study lake. C:N ratios of TPOC were between 6:1 and 22:1 (molar), much lower than the values for terrestrial leaves which were between 39:1 and 48:1 (molar). These low C:N ratios suggest that TPOC may be a useful substrate for aquatic consumers and may supplement in-lake primary production as a food source, especially after wind and rain events when airborne TPOC inputs are high.

/pdf/airborne-carbon-deposition-on-a-remote-forested-lake-2782jcka8y.pdf

Airborne carbon deposition on a remote forested lake

Freshwaters include groundwater, rivers, lakes, and reservoirs These ecosystems represent about 7% of earth’s terrestrial surface area Although aquatic and terrestrial ecosystems appear clearly separate to the human eye, groundwaters, lakes, and rivers are in fact closely connected to terrestrial systems (Magnuson et al 2006) Climate, soils, and water-use haracteristics of terrestrial plants affect infiltration of water to groundwater and runoff to surface waters Terrestrial systems contribute nutrients and organic matter to freshwater systems Rivers in flood fertilize their valleys Terrestrial organisms are eaten by aquatic ones, and vice versa A natural unit for considering coupled terrestrial and aquatic ecosystems is the watershed Within a watershed, ecosystems are closely linked through flows of water, dissolved chemicals, including nutrients and organic matter, and movements of organisms Thus watersheds are natural units of analysis for freshwater resources

Freshwaters: Managing Across Scales in Space and Time

Predicting when the dynamics of a complex system will undergo a sudden transition is difficult New experiments show that the spatial distribution of organisms can indicate when such tipping points are near See Letter p355
 The behaviour of complex systems near tipping points, where a small change can lead to a large shift in the state of the system, is notoriously difficult to predict Recent studies have identified temporal factors such as recovery time and changes in size and timescale of fluctuations that precede some tipping points Lei Dai et al grew populations of the budding yeast that were spatially connected through controlled dispersal between nearest neighbours, and looked for spatiotemporal patterns that anticipated population collapse after perturbation — the introduction of sucrose solution more highly diluted than its surroundings As the distance from the diluted patch increased, yeast population density increased towards a steady state The distance required for recovery by connected populations was much greater when populations were close to collapse This work introduces the concept of 'recovery length' as a spatial counterpart to recovery time, and as boundaries between regions of different quality are ubiquitous in nature, many systems in the oceans and on land might be expected to be subject to such spatial instability

Stephen R. Carpenter

Papers

Temporal variance in lake communities: blue-green algae and the trophic cascade

Water clarity and temperature effects on walleye safe harvest: an empirical test of the safe operating space concept

Airborne carbon deposition on a remote forested lake

Freshwaters: Managing Across Scales in Space and Time

Complex systems: Spatial signatures of resilience