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

https://www.wsl.ch/staff/niklaus.zimmermann/papers/ecomod135_147.pdf

Predictive habitat distribution models in ecology

Species richness is a fundamental measurement of community and regional diversity, and it underlies many ecological models and conservation strategies. In spite of its importance, ecologists have not always appreciated the effects of abundance and sampling effort on richness measures and comparisons. We survey a series of common pitfalls in quantifying and comparing taxon richness. These pitfalls can be largely avoided by using accumulation and rarefaction curves, which may be based on either individuals or samples. These taxon sampling curves contain the basic information for valid richness comparisons, including category‐subcategory ratios (species-to-genus and species-toindividual ratios). Rarefaction methods ‐ both sample-based and individual-based ‐ allow for meaningful standardization and comparison of datasets. Standardizing data sets by area or sampling effort may produce very different results compared to standardizing by number of individuals collected, and it is not always clear which measure of diversity is more appropriate. Asymptotic richness estimators provide lower-bound estimates for taxon-rich groups such as tropical arthropods, in which observed richness rarely reaches an asymptote, despite intensive sampling. Recent examples of diversity studies of tropical trees, stream invertebrates, and herbaceous plants emphasize the importance of carefully quantifying species richness using taxon sampling curves.

/pdf/quantifying-biodiversity-procedures-and-pitfalls-in-the-2ut2f3nw4g.pdf

Quantifying biodiversity: procedures and pitfalls in the measurement and comparison of species richness

▪ Abstract The focus of most ideas on diversity maintenance is species coexistence, which may be stable or unstable. Stable coexistence can be quantified by the long-term rates at which community members recover from low density. Quantification shows that coexistence mechanisms function in two major ways: They may be (a) equalizing because they tend to minimize average fitness differences between species, or (b) stabilizing because they tend to increase negative intraspecific interactions relative to negative interspecific interactions. Stabilizing mechanisms are essential for species coexistence and include traditional mechanisms such as resource partitioning and frequency-dependent predation, as well as mechanisms that depend on fluctuations in population densities and environmental factors in space and time. Equalizing mechanisms contribute to stable coexistence because they reduce large average fitness inequalities which might negate the effects of stabilizing mechanisms. Models of unstable coexitence...

/pdf/mechanisms-of-maintenance-of-species-diversity-340h1nopps.pdf

Mechanisms of Maintenance of Species Diversity

We use two types of age-structured population models to study how the distribution of toxins among segments of the twigs of woody plants, by affecting the feeding behavior of snowshoe hares, might affect snowshoe hare population dynamics. In the first model a twig has $N$ discrete toxin containing segments joined end to end. Depending on species these segments vary tremendously in length. Preferred browse species such as the deciduous shrub birch Betula glandulosa have a small number of long twig segments and defend only the youngest segments near the twig tip. Hares counter this defense by biting off a twig at an older segment, eating only the older segments and rejecting younger, more toxic attached segments. Twigs of less preferred foods, such as the juvenile developmental stages of the evergreen spruces Picea glauca and P. mariana, have an arrangement of toxin producing resin ducts along their twig's long axis that is best modeled using a large number of short segments. We also propose a continuous mo...

A Mathematical Model of Woody Plant Chemical Defenses and Snowshoe Hare Feeding Behavior in Boreal Forests: The Effect of Age-Dependent Toxicity of Twig Segments

A spatially explicit model is developed to simulate the small fish community
and its underlying food web, in the freshwater marshes of the Everglades
The community is simplified to a few small fish species feeding on
periphyton and invertebrates Other compartments are detritus, crayfish, and
a piscivorous fish species This unit food web model is applied to each of
the 10,000 spatial cells on a 100 x 100 pixel landscape Seasonal variation
in water level is assumed and rules are assigned for fish movement in
response to rising and falling water levels, which can cause many spatial
cells to alternate between flooded and dry conditions It is shown that
temporal variations of water level on a spatially heterogeneous landscape
can maintain at least three competing fish species In addition, these
environmental factors can strongly affect the temporal variation of the food
web caused by top-down control from the piscivorous fish

Food web dynamics in a seasonally varying wetland.

Recent theoretical work on mutualism, the interaction between species populations that is mutually beneficial, is reviewed. Several ecological facts that should be addressed in the construction of dynamic models for mutualism are examined. Basic terminology is clarified. (PSB)

Evolution of mutualism between species

Printed on recycled paper Plant communities are key components of the Greater Everglades. In addition to providing food and shelter to higher trophic level species, plants influence abiotic ecosystem processes such as fires. The hydrologic modifications, proposed as part of the Comprehensive Everglades Restoration Plan (CERP), will affect both the spatial distribution of plants through time and the fire regime. Changes in the local complement of plants can influence the frequency and intensity of fires in a given area through consequent changes in flammability and rates of fuel production. Hydrologic restoration may, therefore, contribute to the restoration of more natural fire patterns by altering the local risk of fire in different areas. Fires also play an important role in shaping the floral landscape. For example, some fires burn soils, lowering local topography and changing local hydrologic patterns. Fires also can result in the establishment of fire-climax communities, and therefore, are capable of altering the local plant community structure and composition. Understanding the complex interrelationships among these components and processes is an important part of evaluating hydrologic restoration efforts. Under the Across Trophic Level System Simulation (ATLSS) Program, models have been developed for vegetation succession and fire that incorporate the effects of hydrology. These models examine relative differences under proposed hydrologic changes in the: (1) number, diversity, and spatial configuration of Everglades plant communities; and (2) number, size, frequency, and distribution of fires in the Everglades.

Modeling the effects of hydrology on fire, vegetation dynamics, and their interaction in the Florida Everglades

Using carbon isotope ratios to verify predictions of a model simulating the interaction between coastal plant communities and their effect on ground water salinity

Donald L. DeAngelis

Papers

A Mathematical Model of Woody Plant Chemical Defenses and Snowshoe Hare Feeding Behavior in Boreal Forests: The Effect of Age-Dependent Toxicity of Twig Segments

Food web dynamics in a seasonally varying wetland.

Evolution of mutualism between species

Modeling the effects of hydrology on fire, vegetation dynamics, and their interaction in the Florida Everglades

Using carbon isotope ratios to verify predictions of a model simulating the interaction between coastal plant communities and their effect on ground water salinity