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

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

Summary
1. Here, I present a new, multifunctional phylogenetics package, phytools, for the R statistical computing environment.

2. The focus of the package is on methods for phylogenetic comparative biology; however, it also includes tools for tree inference, phylogeny input/output, plotting, manipulation and several other tasks.

3. I describe and tabulate the major methods implemented in phytools, and in addition provide some demonstration of its use in the form of two illustrative examples.

4. Finally, I conclude by briefly describing an active web-log that I use to document present and future developments for phytools. I also note other web resources for phylogenetics in the R computational environment.

/pdf/phytools-an-r-package-for-phylogenetic-comparative-biology-yli0omoidd.pdf

phytools: an R package for phylogenetic comparative biology (and other things)

The primary rationale for the use of phylogenetically based statistical methods is that phylogenetic signal, the tendency for related species to resemble each other, is ubiquitous. Whether this assertion is true for a given trait in a given lineage is an empirical question, but general tools for detecting and quantifying phylogenetic signal are inadequately developed. We present new methods for continuous-valued characters that can be implemented with either phylogenetically independent contrasts or generalized least-squares models. First, a simple randomization procedure allows one to test the null hypothesis of no pattern of similarity among relatives. The test demonstrates correct Type I error rate at a nominal α = 0.05 and good power (0.8) for simulated datasets with 20 or more species. Second, we derive a descriptive statistic, K, which allows valid comparisons of the amount of phylogenetic signal across traits and trees. Third, we provide two biologically motivated branch-length transformat...

/pdf/testing-for-phylogenetic-signal-in-comparative-data-3lvcin7t3t.pdf

Testing for phylogenetic signal in comparative data: behavioral traits are more labile.

Lizards should be relatively invulnerable to warming: They are very good at evading thermal stress, tolerate high body temperatures, and resist water loss. Nevertheless, on page 894 of this issue, Sinervo et al. ( 1 ) document extinctions of lizard populations on five continents and argue that global warming is responsible. They use a simple biological model, validated against observed extinctions, to predict that warming will drive almost 40% of all global lizard populations extinct by 2080. If their prediction is even close to correct, lizards may be “the new amphibians” ( 2 ) in a race toward extinction.

Are Lizards Toast

Anoles have evolved independently on each island in the Greater Antilles, producing a suite of morphologically-distinct species that utilize different microhabitats. Comparisons among islands indicate that the same set of "ecomorphs"-distantly related species that are similar in morphology, ecology, and behavior-has evolved on each island. Despite considerable work on anoles over the past three decades, much remains to be learned about evolution of the ecomorphs. In particular, previous studies have focused on external measurements of gross limb proportions, tail length, mass, and number of lamellae. Using a variety of techniques, we examined these char- acters in greater detail and investigated a wide variety of other characters. We found that the ecomorph classes represent distinct entities in morphological space when morphological characters are examined in greater detail (e.g., each limb element was treated separately). In addition, we found that the ecomorphs differ in a variety of characters not previously examined, including toe pad area, pectoral and pelvic girdle dimensions, head dimensions, and tail shape. These differences were apparent regardless of how we defined body size, although comparisons of particular characters were affected by which body size variable was used. This finding indicates that convergence in ecomorph evolutibn extends beyond traits directly linked to habitat use and locomotion. We also examined a number of other taxa that have not traditionally been considered to be members of any ecomorph class. We found that many descendants of ecomorphs living on small islands near the Greater Antilles no longer belong to the ecomorph class of their ancestor. Many Lesser Antillean anoles appear to ibe trunk-crown anoles, whereas others do not belong to any ecomorph class. Montane anoles of the Greater Antilles and Chamaelinorops also do not belong to any ecomorph class, but Chamaeleolis, and possibly Phenacosaurus, are twig anoles.

Ecological morphology of caribbean anoles

On the large islands of the Greater Antilles, multi-species communities ofAnolislizards are composed of species specialized to use particular habitats; similar sets of specialized species have evolved independently on each island. We studied species of anoles found on small Caribbean islands. Because these islands contain at most only one other species of anole, we predicted that species on these islands should not be as specialized as Greater Antillean species; rather, they might be expected to exhibit a generalized morphology and a greater breadth of habitat use. Our findings, however, do not confirm these predictions. Lesser Antillean species do not exhibit greater breadth of habitat use than Greater Antillean species, nor do they exhibit a generalized morphology. Most species are ecologically and morphologically similar to specialized trunk-crown anoles of the Greater Antilles, although some species exhibit morphologies unlike those seen in Greater Antillean species. Among descendants of specialized Greater Antillean species occurring on one- or two-species islands, most descendants of trunk-crown species have diverged relatively little, whereas several descendants of trunk-ground anoles have diverged considerably. Consequently, we propose that ancestral species in the Greater Antilles may have been trunk-crown anoles.

Evolutionary consequences of ecological release in caribbean anolis lizards

We measured the force required to pull chameleons from perches of varying diameters and the sprint speed of chameleons on flat surfaces and on perches of varying diameters. The two species examined differ in their degree of terrestriality: Chamaeleo jacksonii is almost completely arboreal, whereas C. dilepis is semi-arboreal and is often observed on the ground. We tested the following hypotheses: (a) each species has relatively greater sprinting and clinging abilities on surfaces corresponding to those it uses most frequently; or (b) a trade-off exists between maximizing clinging and sprinting abilities. The results support the second hypothesis: C. dilepis runs faster than C. jacksonii on almost all diameters, but has poorer clinging ability on all diameters

Trade-Offs Between Sprinting and Clinging Ability in Kenyan Chameleons

Evolutionary ecologists have long debated the extent to which communities in similar environments but different geographic regions exhibit convergence. On the one hand, if species' adaptations and community structure are determined by environmental features, convergence would be expected. However, if historical contingencies have long-lasting effects convergence would be unlikely. Most studies to date have emphasized the differences between communities in similar environments and little quantitative evidence for convergence exists. The application of comparative phylogenetic methods to ecological studies provides an opportunity to further investigate hypotheses of convergence. We compared the evolutionary patterns of structural ecology and morphology of 42 species of iguanian lizards from deserts of Australia and North America. Using a comparative approach, we found that evolutionary convergence of ecology and morphology occurs both in overall, community-wide patterns and in terms of pairs of highly similar intercontinental pairs of species. This result indicates that in these desert lizards, deterministic adaptive evolution shapes community patterns and overrides the historical contingencies unique to particular lineages.

/pdf/intercontinental-community-convergence-of-ecology-and-13g1jrx9vi.pdf

Jonathan B. Losos

Papers

Are Lizards Toast

Ecological morphology of caribbean anoles

Evolutionary consequences of ecological release in caribbean anolis lizards

Trade-Offs Between Sprinting and Clinging Ability in Kenyan Chameleons

Intercontinental community convergence of ecology and morphology in desert lizards