Silene as a model system in ecology and evolution.

The genus Silene, studied by Darwin, Mendel and other early scientists, is re-emerging as a system for studying interrelated questions in ecology, evolution and developmental biology. These questions include sex chromosome evolution, epigenetic control of sex expression, genomic conflict and speciation. Its well-studied interactions with the pathogen Microbotryum has made Silene a model for the evolution and dynamics of disease in natural systems, and its interactions with herbivores have increased our understanding of multi-trophic ecological processes and the evolution of invasiveness. Molecular tools are now providing new approaches to many of these classical yet unresolved problems, and new progress is being made through combining phylogenetic, genomic and molecular evolutionary studies with ecological and phenotypic data.

Structural, metamorphic and geochronological relations between the Zanskar Shear Zone and the Miyar Shear Zone (NW Indian Himalaya): Evidence for two distinct tectonic structures and implications for the evolution of the High Himalayan Crystalline of Zanskar

The geologic structures and metamorphic zonation of the northwestern Indian Himalaya contrast significantly with those in the central and eastern parts of the range, where the high-grade metamorphic rocks of the High Himalayan Crystalline (HHC) thrust southward over the weakly metamorphosed sediments of the Lesser Himalaya along the Main Central Thrust (MCT). Indeed, the hanging wall of the MCT in the NW Himalaya mainly consists of the greenschist facies metasediments of the Chamba zone, whereas HHC high-grade rocks are exposed more internally in the range as a large-scale dome called the Gianbul dome. This Gianbul dome is bounded by two oppositely directed shear zones, the NE-dipping Zanskar Shear Zone (ZSZ) on the northern flank and the SW-dipping Miyar Shear Zone (MSZ) on the southern limb. Current models for the emplacement of the HHC in NW India as a dome structure differ mainly in terms of the roles played by both the ZSZ and the MSZ during the tectonothermal evolution of the HHC. In both the channel flow model and wedge extrusion model, the ZSZ acts as a backstop normal fault along which the high-grade metamorphic rocks of the HHC of Zanskar are exhumed. In contrast, the recently proposed tectonic wedging model argues that the ZSZ and the MSZ correspond to one single detachment system that operates as a subhorizontal backthrust off of the MCT. Thus, the kinematic evolution of the two shear zones, the ZSZ and the MSZ, and their structural, metamorphic and chronological relations appear to be diagnostic features for discriminating the different models. In this paper, structural, metamorphic and geochronological data demonstrate that the MSZ and the ZSZ experienced two distinct kinematic evolutions. As such, the data presented in this paper rule out the hypothesis that the MSZ and the ZSZ constitute one single detachment system, as postulated by the tectonic wedging model. Structural, metamorphic and geochronological data are used to present an alternative tectonic model for the large-scale doming in the NW Indian Himalaya involving early NE-directed tectonics, weakness in the upper crust, reduced erosion at the orogenic front and rapid exhumation along both the ZSZ and the MSZ.

The evolution of judgement bias in indirect reciprocity.

Indirect reciprocity is a form of reciprocity where help is given to individuals based on their reputation. In indirect reciprocity, bad acts (such as not helping) reduce an individual's reputation while good acts (such as helping) increase an individual's reputation. Studies of indirect reciprocity assume that good acts and bad acts are weighted equally when assessing the reputation of an individual. As different information can be processed in different ways, this is not likely to be the case, and it is possible that an individual could bias an actor's reputation by putting more weight to acts of defection (not helping) than acts of co-operation (helping) or vice versa. We term this difference 'judgement bias', and build an individual-based model of image scoring to investigate the conditions under which it may evolve. We find that, if the benefits of co-operation are small, judgement bias is weighted towards acts perceived to be bad; if the benefits are high, the reverse is true. Our result is consistent under both scoring and standing strategies, and we find that allowing judgement bias to evolve increases the level of co-operation in the population.

The genome sequence of taurine cattle: a window to ruminant biology and evolution.

To understand the biology and evolution of ruminants, the cattle genome was sequenced to about sevenfold coverage. The cattle genome contains a minimum of 22,000 genes, with a core set of 14,345 orthologs shared among seven mammalian species of which 1217 are absent or undetected in noneutherian (marsupial or monotreme) genomes. Cattle-specific evolutionary breakpoint regions in chromosomes have a higher density of segmental duplications, enrichment of repetitive elements, and species-specific variations in genes associated with lactation and immune responsiveness. Genes involved in metabolism are generally highly conserved, although five metabolic genes are deleted or extensively diverged from their human orthologs. The cattle genome sequence thus provides a resource for understanding mammalian evolution and accelerating livestock genetic improvement for milk and meat production.

On the evolution of harming and recognition in finite panmictic and infinite structured populations.

Natural selection may favor two very different types of social behaviors that have costs in vital rates (fecundity and/or survival) to the actor: helping behaviors, which increase the vital rates of recipients, and harming behaviors, which reduce the vital rates of recipients. Although social evolutionary theory has mainly dealt with helping behaviors, competition for limited resources creates ecological conditions in which an actor may benefit from expressing behaviors that reduce the vital rates of neighbors. This may occur if the reduction in vital rates decreases the intensity of competition experienced by the actor or that experienced by its offspring. Here, we explore the joint evolution of neutral recognition markers and marker-based costly conditional harming whereby actors express harming, conditional on actor and recipient bearing different conspicuous markers. We do so for two complementary demographic scenarios: finite panmictic and infinite structured populations. We find that marker-based conditional harming can evolve under a large range of recombination rates and group sizes under both finite panmictic and infinite structured populations. A direct comparison with results for the evolution of marker-based conditional helping reveals that, if everything else is equal, marker-based conditional harming is often more likely to evolve than marker-based conditional helping.

Structure of the extracellular domains of human and Xenopus Fn14: implications in the evolution of TWEAK and Fn14 interactions.

TWEAK (TNF homologue with weak apoptosis-inducing activity) and Fn14 (fibroblast growth factor-inducible protein 14) are members of the tumor necrosis factor (TNF) ligand and receptor super-families. Having observed that Xenopus Fn14 cross-reacts with human TWEAK, despite its relatively low sequence homology to human Fn14, we examined the conservation in tertiary fold and binding interfaces between the two species. Our results, combining NMR solution structure determination, binding assays, extensive site-directed mutagenesis and molecular modeling, reveal that, in addition to the known and previously characterized β-hairpin motif, the helix-loop-helix motif makes an essential contribution to the receptor/ligand binding interface. We further discuss the insight provided by the structural analyses regarding how the cysteine-rich domains of the TNF receptor super-family may have evolved over time. DATABASE: Structural data are available in the Protein Data Bank/BioMagResBank databases under the accession codes 2KMZ, 2KN0 and 2KN1 and 17237, 17247 and 17252. STRUCTURED DIGITAL ABSTRACT: TWEAK binds to hFn14 by surface plasmon resonance (View interaction) xeFn14 binds to TWEAK by enzyme linked immunosorbent assay (View interaction) TWEAK binds to xeFn14 by surface plasmon resonance (View interaction) hFn14 binds to TWEAK by enzyme linked immunosorbent assay (View interaction).

The fixation of metacentric chromosomes during the chromosomal evolution in the common shrew (Sorex araneus, Insectivora)

Rb fusions between acrocentric chromosomes leading to metacentrics tend to become fixed during the chromosomal evolution in the common shrew. Using microsatellite markers preliminary results show that populations are only slightly subdivided and genetic drift seems not to play an important role for the fixation of metacentrics. A significant segregation distortion in favour of metacentric chromosomes was found during male meiosis. This suggests that cytological factors such as facilitated fusion between acrocentric chromosomes or choice-effects at the level of gametes are more likely to play a role for the chromosomal evolution in the common shrew.

Developmental constraints on vertebrate genome evolution.

Constraints in embryonic development are thought to bias the direction of evolution by making some changes less likely, and others more likely, depending on their consequences on ontogeny. Here, we characterize the constraints acting on genome evolution in vertebrates. We used gene expression data from two vertebrates: zebrafish, using a microarray experiment spanning 14 stages of development, and mouse, using EST counts for 26 stages of development. We show that, in both species, genes expressed early in development (1) have a more dramatic effect of knock-out or mutation and (2) are more likely to revert to single copy after whole genome duplication, relative to genes expressed late. This supports high constraints on early stages of vertebrate development, making them less open to innovations (gene gain or gene loss). Results are robust to different sources of data -- gene expression from microarrays, ESTs, or in situ hybridizations; and mutants from directed KO, transgenic insertions, point mutations, or morpholinos. We determine the pattern of these constraints, which differs from the model used to describe vertebrate morphological conservation ("hourglass" model). While morphological constraints reach a maximum at mid-development (the "phylotypic" stage), genomic constraints appear to decrease in a monotonous manner over developmental time.

Evolution pondérale des patients au cours du traitement par autogreffe de cellules souches hématopoïétiques

Introduction et But de l'étude. - La transplantation de cellules souches hématopoïétiques est un des traitements proposés dans le cadre de certaines hémopathies malignes. Elle est fréquemment associée à une anorexie, des nausées et des douleurs buccales limitant les ingesta. Chez ces patients, il a été démontré qu'une altération du statut nutritionnel était associée à une durée de séjour hospitalier augmentée. Si l'évolution hospitalière est généralement bien documentée, peu d'informations nutritionnelles sur la période post-greffe sont disponibles. L'objectif de cette étude est de documenter l'évolution pondérale en fonction des différentes phases de traitement.Matériel et Méthodes. - Cette étude rétrospective a porté sur un collectif de patients suivis par la consultation ambulatoire d'onco-hématologie. Ont été inclus tous les dossiers de patients ayant bénéficié d'une autogreffe depuis plus de 100 jours. Les variables démographiques, médicales, nutritionnelles et fonctionnelles ont été recueillies aux périodes suivantes de prise en charge : lors du diagnostic (P1), à l'admission (P2) et à la sortie de l'hôpital lors de l'autogreffe (P3) et au 100e jour post-autogreffe (P4).Résultats. - L'échantillon était composé de 22 hommes et 11 femmes, ayant une moyenne d'âge de 52 ± 11 ans, un BMI moyen de 26,7 ± 4,2 et souffrant de lymphome (49 %), myélome (45 %), maladie de Hodgkin (3 %) ou amyloïdose (3 %). La durée moyenne d'hospitalisation pour l'autogreffe est de 21 ± 4 jours. À P1 et P3, seul 1 patient présentait un BMI < 18,5, et aucun patient aux autres périodes étudiées. Un BMI supérieur à 25 kg/m2 était présent chez 64 % à P1, 67 % à P2, 45 % à P3, 48 % à P4. Trente pour cent des patients perdent plus de 5 % de leur poids entre P1 et P4 dont 80 % sont des hommes. Leur BMI moyen à P1 est de 28,8 ± 3,3 kg/m2 (10 % de normal, 60 % de surpoids et 30 % d'obésité) et à P4 de 26,7 ± 3,1 kg/m2 (30 % de normal, 60 % de surpoids et 10 % d'obésité). Ces patients ont une perte de poids de 2,4 ± 4,5 % entre P1 et P2, de 8,6 ± 4,4 % entre P1 et P3 et de 7,4 ± 1,7 % entre P1 et P4.Durant le séjour hospitalier, les patients perdent en moyenne 5,6 ± 2,9 % de leur poids d'entrée (P2). Les jours qui suivent l'autogreffe50 % des sujets perdent 6 ± 3,5 %, Durant l'hospitalisation, 33 % des patients ont reçu un support nutritionnel. La prescription d'un support nutritionnel est corrélé avec la présence de candidose (r = 0,350 ; p = 0,044).Conclusion. - La majorité de ces patients oncohématologiques traités par autogreffe de cellules souches perdent du poids pendant l'hospitalisation et ceci persiste au 100e jour post-greffe pour 21 % de l'échantillon. Le BMI est élevé au moment du diagnostic et le reste tout au long de la prise en charge. Une étude prospective sur un échantillon plus large pourrait dans le futur permettre de déterminer les facteurs prédictifs d'une perte de poids persistante 3 mois après une autogreffe.

Prepupal Building Behavior in Drosophila melanogaster and Its Evolution under Resource and Time Constraints.

Structures built by animals are a widespread and ecologically important 'extended phenotype'. While its taxonomic diversity has been well described, factors affecting short-term evolution of building behavior within a species have received little experimental attention. Here we describe how, given the opportunity, wandering Drosophila melanogaster larvae often build long tunnels in agar substrates and embed their pupae within them. These embedded larvae are characterized by a longer egg-to-pupariation developmental time than larvae that pupate on the surface. Assuming that such building behaviors are likely to be energetically costly and/or time consuming, we hypothesized that they should evolve to be less pronounced under resource or time limitation. In accord with this prediction, larvae from populations evolved for 160 generations under a regime that combines larval malnutrition with limited developmental time dug shorter tunnels than larvae from control unselected populations. However, the proportion of larvae that embedded before pupation did not differ between the malnutrition-adapted and control populations, suggesting that tunnel length and likelihood of embedding before pupation are controlled by different genetic loci. The behaviors exhibited by wandering larvae of Drosophila melanogaster prior to pupation offer a model system to study evolution of animal building behaviors because the tunneling and embedding phenotypes are simple, facultative and highly variable.

Institutional change and the evolution of the regulatory state: evidence from the Swiss case

This article examines institutional change in a case that was expected to be particularly resilient but showed considerable structural transformation: the institutionalization of the regulatory state in Switzerland. This process is illustrated through the establishment of independent regulatory agencies (IRAs) in four areas: banking and finance; telecommunications; electricity; and competition. The theoretical framework developed by Streeck, Thelen and Mahoney is used to explore hypotheses about the modes of institutional change, with the methodology of diachronic within-case study. Results confirm only partially the expectations, pointing to layering and displacement as the prevalent modes of change. The concluding part discusses the type and the direction of change as additional explanatory factors.

High-precision dating and origin of synsedimentary volcanism in the Late Carboniferous Salvan-Dorenaz basin (Aiguilles-Rouges Massif, Western Alps)

Late Variscan volcanic activity is documented in the Late Carboniferous Salvan-Dorenaz sedimentary basin and in the neighboring basement units of the Aiguilles-Rouges and Mont-Blanc crystalline massifs (Western Alps). Precise U/Pb isotopic dating, zircon morphology and geochemical analyses indicate that volcanism occurred during short-lived pulses and that coexisting crustal and mantle sources were involved in the production of melts. Volcanic and subvolcanic products were emplaced along major N-S to NNE-SSW transtensional fracture zones, similar to the ones that governed intense basement exhumation and that favored the formation and filling of the Late Carboniferous Salvan-Dorenaz continental basin. In the Aiguilles-Rouges massif, dacitic flows outcropping at the base of the Salvan-Dorenaz basin erupted at 308 +/- 3 Ma; they represent the surface equivalent of the nearby Vallorcine peraluminous granite and associated rhyolitic dykes (311 +/- 17 Ma). In the Mont Blanc massif, calc-alkaline rhyolitic dykes were emplaced simultaneously (307 +/- 2 Ma) at shallow crustal levels, but they derive from deeper magma sources denoting enhanced mantellic activity. Recently identified tuffs and volcaniclastic layers embedded at different levels of the Salvan-Dorenaz stratigraphic record testify a 295 +3/-4 Ma old episode of highly explosive volcanism from distant volcanic centers, possibly located in the Aar-Gotthard massifs (Central Alps). Their zircon typology is highly heterogeneous. documenting wall-rock contamination of the melts and/or admixture of crustal sediments, whereas consistent subpopulations point to high-temperature magmas of deep-seated origin and alkaline affinity. The dated volcanic layers from the Salvan-Dorenaz basin set the beginning of the detrital sedimentation at 308 +/- 3 Ma and constrain the deposition of 1.5-1.7 km thick of elastic sediments within a time span of 10-15 Ma. These results infer minimum, long-term subsidence rates during basin evolution in the order of >0.1 mm/a, while in the surrounding basement units estimated exhumation rates are in the range of 1 mm/a. All dated rocks contain inherited zircon populations about 350, 450 or 600 Ma old.

Trace element chemistry and U-Pb dating of zircons from oceanic gabbros and their relationship with whole rock composition (Lanzo, Italian Alps)

The U-Pb ages and the trace element content of zircon U-Pb along with major and trace element whole rock data on gabbroic dikes from the Lanzo lherzolitic massif, N-Italy, have been determined to constrain crustal accretion in ocean-continent transition zones. Three Fe-Ti gabbros were dated from the central and the southern part of the massif providing middle Jurassic ages of 161 +/- 2, 158 +/- 2 and 163 +/- 1 Ma, which argue for magmatic activity over few millions of years. Zircon crystals are characterized by high but variable Th/U ratios, rare earth element patterns enriched in heavy rare earths, pronounced positive Ce and negative Eu-anomalies consistent with crystallization after substantial plagioclase fractionation. The zircon trace element composition coupled with whole rock chemistry was used to reconstruct the crystallization history of the gabbros. A number of gabbros crystallized in situ, and zircon precipitated from trapped, intercumulus liquid, while other gabbros represent residual liquids that were extracted from a cumulus pile and crystallized along syn-magmatic shear zones. We propose a model in which the emplacement mechanism of gabbroic rocks in ocean-continent transition zones evolves from in situ crystallization to stratified crystallization with efficient extraction of residual liquid along syn-magmatic shear zones. Such an evolution of the crystallization history is probably related to the thermal evolution of the underlying mantle lithosphere.