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.cs.princeton.edu/~schapire/papers/ecolmod.pdf

Maximum entropy modeling of species geographic distributions

So far in this course we have dealt entirely with the evolution of characters that are controlled by simple Mendelian inheritance at a single locus. There are notes on the course website about gametic disequilibrium and how allele frequencies change at two loci simultaneously, but we didn’t discuss them. In every example we’ve considered we’ve imagined that we could understand something about evolution by examining the evolution of a single gene. That’s the domain of classical population genetics. For the next few weeks we’re going to be exploring a field that’s actually older than classical population genetics, although the approach we’ll be taking to it involves the use of population genetic machinery. If you know a little about the history of evolutionary biology, you may know that after the rediscovery of Mendel’s work in 1900 there was a heated debate between the “biometricians” (e.g., Galton and Pearson) and the “Mendelians” (e.g., de Vries, Correns, Bateson, and Morgan). Biometricians asserted that the really important variation in evolution didn’t follow Mendelian rules. Height, weight, skin color, and similar traits seemed to

Human biochemical genetics

Causal attribution of recent biological trends to climate change is complicated because non-climatic influences dominate local, short-term biological changes. Any underlying signal from climate change is likely to be revealed by analyses that seek systematic trends across diverse species and geographic regions; however, debates within the Intergovernmental Panel on Climate Change (IPCC) reveal several definitions of a 'systematic trend'. Here, we explore these differences, apply diverse analyses to more than 1,700 species, and show that recent biological trends match climate change predictions. Global meta-analyses documented significant range shifts averaging 6.1 km per decade towards the poles (or metres per decade upward), and significant mean advancement of spring events by 2.3 days per decade. We define a diagnostic fingerprint of temporal and spatial 'sign-switching' responses uniquely predicted by twentieth century climate trends. Among appropriate long-term/large-scale/multi-species data sets, this diagnostic fingerprint was found for 279 species. This suite of analyses generates 'very high confidence' (as laid down by the IPCC) that climate change is already affecting living systems.

/pdf/a-globally-coherent-fingerprint-of-climate-change-impacts-5duzh6vc6b.pdf

A globally coherent fingerprint of climate change impacts across natural systems

Physiological research suggests that tropical insects are particularly sensitive to temperature, but information on their responses to climate change has been lacking—even though the majority of all terrestrial species are insects and their diversity is concentrated in the tropics. Here, we provide evidence that tropical insect species have already undertaken altitude increases, confirming the global reach of climate change impacts on biodiversity. In 2007, we repeated a historical altitudinal transect, originally carried out in 1965 on Mount Kinabalu in Borneo, sampling 6 moth assemblages between 1,885 and 3,675 m elevation. We estimate that the average altitudes of individuals of 102 montane moth species, in the family Geometridae, increased by a mean of 67 m over the 42 years. Our findings indicate that tropical species are likely to be as sensitive as temperate species to climate warming, and we urge ecologists to seek other historic tropical samples to carry out similar repeat surveys. These observed changes, in combination with the high diversity and thermal sensitivity of insects, suggest that large numbers of tropical insect species could be affected by climate warming. As the highest mountain in one of the most biodiverse regions of the world, Mount Kinabalu is a globally important refuge for terrestrial species that become restricted to high altitudes by climate warming.

https://www.pnas.org/content/pnas/106/5/1479.full.pdf

Elevation increases in moth assemblages over 42 years on a tropical mountain

Evolutionary and population dynamics models suggest that the migration rate will affect the probability of survival in fragmented landscapes. Using data for butterfly species in the fragmented Brit...

Dispersal and extinction in fragmented landscapes

1. Studies of the spatio-temporal dynamics and structure of populations have identified many categories of population type. However, recognized categories intergrade, making it difficult to assign empirical population systems to single categories.



2. We suggest that most population categories can be arranged along two axes that combine per capita birth (B), death (D), emigration (E) and immigration (I) rates. The ‘Compensation Axis’ describes the source-sink component of population structure, with source populations exporting individuals (B > D, E > I) and sinks and pseudosinks consuming individuals (B < D, E < I). The ‘Mobility Axis’ describes the involvement of a local population in regional (I + E) rather than local (B + D) processes, running from separate populations, through metapopulations, to patchy populations.



3. Each sample area within a spatially structured population system can potentially be assigned to a position along each of these axes, with individual sample areas weighted by local population size. The positions of these sample areas and their relative weightings allow the relative importance of different types of process to be judged. A worked exampled is provided, using the butterfly Hesperia comma. This approach shifts the emphasis from pattern (categories that real population systems do not fit) onto process.



4. In many systems, continuous variation in habitat quality and demographic parameters make clear distinctions between ‘habitat’ and ‘non-habitat’ difficult to sustain. In such cases, we advocate the use of a spatial grid system, with effects of patch size and isolation combined into a single, weighted distance function (neighbourhood).



5. The relative importance of different processes depends on the spatial scale at which the system is observed. This again emphasizes the value of a process-based approach.

The spatial structure of populations

1. Metapopulation dynamics of the silver-spotted skipper butterfly Hesperia comma were studied between 1982 and 1991 along a 25-km stretch of chalk hills on the North Downs, Surrey, UK. Sixty-nine patches of suitable habitat were identified, of which 48 were occupied in 1982. Over the 9-year period, 12 patches were colonized, seven went extinct and nine patches remained vacant. Patches were more likely to be colonized if they were relatively large and close to other large, occupied patches. Local populations in small, isolated patches were more likely to go extinct. 2. Within a 70-ha section of a metapopulation, mark-release-recapture techniques were used in 1994 to investigate the effects of local patch area and isolation on movement of individuals among local patches. 988 butterflies were marked of which 133 moved between patches. 67% of between-patch movements were less than 50 m, although the longest recorded distance moved was 1070 m. Butterflies were most likely to move between large patches that were close together. 3. Metapopulation models have assumed that the distribution of distances moved by migrants follows a negative-exponential function. In our study, this distribution fitted an inverse-power function better than a negative-exponential. The under-estimation of long-distance migration by negative exponentials, compared with inverse power functions, may explain why theoretical models have under-estimated the number of occupied patches in metapopulations of H. comma following natural colonization. 4. Per capita emigration and immigration rates were significantly higher in small patches (area < 0.07 ha) compared with medium-sized (0.33-0.78 ha) or large patches (5.66 ha). However, in absolute numbers, more emigrants came from the largest patch where the source population was the largest. 5. The population system studied here shares attributes of several theoretical types of spatially structured population (patchy population, metapopulation, mainland-island system, non-equilibrium system) depending on the temporal and spatial scale examined. The distribution and dynamics of metapopulations should be regarded as being affected by a variety of behavioural and population processes, and real metapopulations can rarely be characterized as a single theoretical type.

Effects of habitat patch size and isolation on dispersal by Hesperia comma butterflies : implications for metapopulation structure

Evidence of anthropogenic global climate change is accumulating, but its potential consequences for insect distributions have received little attention. We use a 'climate response surface' model to investigate distribution changes at the northern margin of the speckled wood butterfly, Pararge aegeria. We relate its current European distribution to a combination of three bioclimatic variables. We document that P. aegeria has expanded its northern margin substantially since 1940, that changes in this species' distribution over the past 100 years are likely to have been due to climate change, and that P. aegeria will have the potential to shift its range margin substantially northwards under predicted future climate change. At current rates of expansion, this species could potentially colonize all newly available climatically suitable habitat in the UK over the next 50 years or more. However, fragmentation of habitats can affect colonization, and we show that availability of habitat may be constraining range expansion of this species at its northern margin in the UK. These lag effects may be even more pronounced in less-mobile species inhabiting more fragmented landscapes, and highlight how habitat distribution will be crucial in predicting species' responses to future climate change.

/pdf/climate-and-habitat-availability-determine-20th-century-2dzrp31js5.pdf

Chris D. Thomas

Papers

Elevation increases in moth assemblages over 42 years on a tropical mountain

Dispersal and extinction in fragmented landscapes

The spatial structure of populations

Effects of habitat patch size and isolation on dispersal by Hesperia comma butterflies : implications for metapopulation structure

Climate and habitat availability determine 20th century changes in a butterfly's range margin