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

Identifying and quantifying planetary boundaries that must not be transgressed could help prevent human activities from causing unacceptable environmental change, argue Johan Rockstrom and colleagues.

/pdf/a-safe-operating-space-for-humanity-tynyc6i2kf.pdf

A safe operating space for humanity

The planetary boundaries framework defines a safe operating space for humanity based on the intrinsic biophysical processes that regulate the stability of the Earth system. Here, we revise and update the planetary boundary framework, with a focus on the underpinning biophysical science, based on targeted input from expert research communities and on more general scientific advances over the past 5 years. Several of the boundaries now have a two-tier approach, reflecting the importance of cross-scale interactions and the regional-level heterogeneity of the processes that underpin the boundaries. Two core boundaries—climate change and biosphere integrity—have been identified, each of which has the potential on its own to drive the Earth system into a new state should they be substantially and persistently transgressed.

/pdf/planetary-boundaries-guiding-human-development-on-a-changing-5gmf909etg.pdf

Planetary boundaries: Guiding human development on a changing planet

Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the re- lationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are struc- tured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain.

/pdf/effects-of-biodiversity-on-ecosystem-functioning-a-consensus-13j8vabcus.pdf

Effects of biodiversity on ecosystem functioning: a consensus of current knowledge

Building phylogenies: are the big easy?

Ecology, evolution, and historical events all contribute to biogeographic patterns, but studies that integrate them are scarce. Here we focus on how biotic exchanges of mammals during the Late Cenozoic have contributed to current geographic body size patterns. We explore differences in the environmental correlates and phylo- genetic patterning of body size between groups of mammals partic- ipating and not participating in past biotic exchanges. Both the as- sociation of body size with environmental predictors and its phylogenetic signal were stronger for groups that immigrated into North or South America than for indigenous groups. This pattern, which held when extinct clades were included in the analyses, can be interpreted on the basis of the length of time that clades have had to diversify and occupy niche space. Moreover, we identify a role for historical events, such as Cenozoic migrations, in configuring contemporary mammal body size patterns and illustrate where these influences have been strongest for New World mammals.

http://www3.uah.es/marodriguez/MARodriguez_Papers/Morales-Castilla_etal_2012_AmNat.pdf

The Imprint of Cenozoic Migrations and Evolutionary History on the Biogeographic Gradient of Body Size in New World Mammals

The chapter presents both phylogenetic and nonphylogenetic comparative analysis of how testes mass, sperm numbers, and sperm length scale with body mass in Marsupials and Monotremes. In eutherian mammals, a negative correlation between body mass and sperm size, as indicated by the length of the sperm tail, occurs. When data for individual species are examined, it became clear that for species within the same genus and often family, the data shows similar trends suggesting a phylogenetic influence, and that, for some groups there is a marked deviation from the average body mass. However, data on social organization and information on breeding systems, copulatory behavior and paternity guards are relatively sparse. But, in some cases, the occurrence of a multimale breeding system is evident, with the potential for intermale sperm competition. These species tend to have large relative testis size and high sperm numbers, thus the presence or absence of intermale sperm competition is likely to be one of the factors responsible for the variation in relative mass of the testis in marsupial species. Sperm competition is one of the driving forces that influence testis size and sperm numbers in this group of animals.

Reproduction, mating strategies, and sperm competition in marsupials and monotremes

The world’s forests are crucially important for both biodiversity conservation and climate mitigation. New forest status and forest change spatial layers using remotely sensed data have revolutionised forest monitoring globally, and provide fine-scale deforestation alerts that can be actioned in near-real time. However, existing products are restricted to representing tree cover and do not reflect the considerable spatial variation in the biological importance of forests. Here we link modelled biodiversity values to remotely sensed data on tree cover to develop global maps of forest biodiversity significance (based on the rarity-weighted richness of forest mammal, bird, amphibian and conifer species) and forest biodiversity intactness (based on the modelled relationship between anthropogenic pressures and community intactness). The strengths and weaknesses of these products for policy and local decision-making are reviewed and we map out future improvements and developments that are needed to enhance their usefulness.

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Measuring Forest Biodiversity Status and Changes Globally

The robust macro-ecological observation that there are more small-bodied species implies that smallbodied organisms have experienced elevated net rates of diversification. We investigate the role of body size in creating non-random differences in rates of cladogenesis using a set of 38 species-level phylogenies drawn from a range of animal groups. We use independent contrasts to explore the relationship between body size and species richness within individual phylogenies and across related sets of phylogenies. We also carry out a meta-analysis looking for associations between body size and species richness across the taxa. We find little evidence for increased cladogenesis among small-bodied organisms within taxa, and no evidence for any consistent differences between taxa. We explore possible explanations for the inconsistency of our findings with macro-ecological patterns.

/pdf/are-most-species-small-not-within-species-level-phylogenies-3ahia3mp34.pdf

Andy Purvis

Papers

Building phylogenies: are the big easy?

The Imprint of Cenozoic Migrations and Evolutionary History on the Biogeographic Gradient of Body Size in New World Mammals

Reproduction, mating strategies, and sperm competition in marsupials and monotremes

Measuring Forest Biodiversity Status and Changes Globally

Are most species small? Not within species-level phylogenies.