Jonathan B. Losos

Bio: Jonathan B. Losos is an academic researcher from Washington University in St. Louis. The author has contributed to research in topics: Anolis & Adaptive radiation. The author has an hindex of 89, co-authored 274 publications receiving 28673 citations. Previous affiliations of Jonathan B. Losos include University of California, Davis & Avila University.

Do the relationships between hindlimb anatomy and sprint speed variation differ between sexes in Anolis lizards

Abstract: The ability of an animal to run fast has important consequences on its survival capacity and overall fitness. Previous studies have documented how variation in the morphology of the limbs is related to variation in locomotor performance. Although these studies have suggested direct relations between sprint speed and hindlimb morphology, few quantitative data exist. Consequently, it remains unclear whether selection acts in limb segment lengths, overall muscle mass or muscle architecture (e.g. muscle fiber length and cross-sectional area). Here, we investigate whether muscle architecture (mass, fiber length and physiological cross-sectional area), hindlimb segment dimensions, or both, explain variation in sprint speed across 14 species of Anolis lizards. Moreover, we test whether similar relationships exist between morphology and performance for both sexes, which may not be the case given the known differences in locomotor behavior and habitat use. Our results show that the main driver of sprint speed is the variation in femur length for both males and females. Our results further show sexual dimorphism in the traits studied and, moreover, show differences in the traits that predict maximal sprint speed in males and females. For example, snout vent length and overall muscle mass are also good predictors of sprint speed in males, whereas no relationships between muscle mass and sprint speed was observed in females. Only a few significant relationships were found between muscle architecture (fiber length, cross-sectional area) and sprint speed in male anoles, suggesting that overall muscles size, rather than muscle architecture, appears to be under selection.

A Multigenerational Field Experiment on Eco-evolutionary Dynamics of the Influential Lizard Anolis sagrei: A Mid-term Report

Abstract: Only a handful of multi-generational experiments in natural systems of eco-evolutionary dynamics currently exist, despite Fussmann et al's call for more such studies nearly a decade ago To perform such a study, in 2008 we introduced the lizard Leiocephalus carinatus, a predator (and possible food competitor) of the lizard Anolis sagrei, to seven islands having A sagrei, with seven unmanipulated islands having A sagrei as controls Almost immediately, L carinatus, which is larger and more terrestrial than A sagrei, caused a major habitat shift in A sagrei away from the ground and toward higher and thinner perches; focal behavioral surveys showed that on islands where its predator was introduced, A sagrei had less conspicuous visual displays The expected pattern for density of A sagrei is that it would decrease markedly at first via predation from the larger lizard, but then it would increase as the habitat shift selected for individuals better able to live in higher vegetation Data through 2015

Ecology of the Flap-Necked Chameleon Chamaeleo dilepis In Southern Africa

Abstract: We quantified sexual size dimorphism, reproduction, and diet in the flap-necked chameleon, Chamaeleo dilepis, using museum specimens. Females were larger than males in both snout-vent length (SVL) and pelvic width. The smallest sexually reproductive female was 80 mm SVL, whereas the smallest mature male was 60 mm. Female body size also correlated with clutch size (mean: 44.2, range: 19–74) and volume, suggesting the female-biased size dimorphism may be the product of fecundity selection. Males and females have slightly asynchronous reproductive cycles but breed during spring–summer. Chamaeleo dilepis feeds on a range of arthropods, but their diet is dominated both numerically and volumetrically by orthopterans, followed by coleopterans.

Parallel increases in grip strength in two species of Anolis lizards after a major hurricane on Dominica

Abstract: A recent study showed that hurricanes can act as selective agents affecting the phenotype of anole populations subjected to these extreme climatic events. Specifically, Anolis lizards that survived hurricanes were shown to have larger toepads than those that did not. To test whether hurricanes more generally impact populations of Anolis lizards, we collected data on toepad size, lamella number and grip strength for two species of Anolis on the island of Dominica in 2018 and compared them with data collected in 2016 before Hurricane Maria devastated the island. Our results show that populations of both species showed higher clinging forces in 2018, consistent with our predictions that lizards that are better clingers would be more likely to survive hurricanes. Unexpectedly, the increase in clinging force was not accompanied by an increase in toepad size or lamella number, suggesting that the increase in clinging strength is more likely driven by changes at the level of the setae microstructure. While the mechanism driving this pattern cannot be determined until future before/after hurricane comparisons are made, our data provide further evidence that hurricanes may be a previously overlooked driver of form and function in Anolis lizards.

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

Abstract: 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。

The Theory of Island Biogeography

Abstract: 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

Human biochemical genetics

Abstract: 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

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

Abstract: 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.

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

Abstract: 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...