TY - JOUR AB - In this Letter, we explore experimentally the phase behavior of a dense active suspension of self-propelled colloids. In addition to a solidlike and gaslike phase observed for high and low densities, a novel cluster phase is reported at intermediate densities. This takes the form of a stationary assembly of dense aggregates—resulting from a permanent dynamical merging and separation of active colloids—whose average size grows with activity as a linear function of the self-propelling velocity. While different possible scenarios can be considered to account for these observations—such as a generic velocity weakening instability recently put forward—we show that the experimental results are reproduced mathematically by a chemotactic aggregation mechanism, originally introduced to account for bacterial aggregation and accounting here for diffusiophoretic chemical interaction between colloidal swimmers. AU - Theurkauff, I. AU - Cottin-Bizonne, C. AU - Palacci, Jérémie A AU - Ybert, C. AU - Bocquet, L. ID - 9014 IS - 26 JF - Physical Review Letters SN - 00319007 TI - Dynamic clustering in active colloidal suspensions with chemical signaling VL - 108 ER - TY - JOUR AB - We demonstrate how to appropriately estimate the zero-frequency (static) hyperpolarizability of an organic molecule from its charge distribution, and we explore applications of these estimates for identifying and evaluating new organic nonlinear optical (NLO) materials. First, we calculate hyperpolarizabilities from Hartree-Fock-derived charge distributions and find order-of-magnitude agreement with experimental values. We show that these simple arithmetic calculations will enable systematic searches for new organic NLO molecules. Second, we derive hyperpolarizabilities from crystallographic data using a multipolar charge-density analysis and find good agreement with empirical calculations. This demonstrates an experimental determination of the full static hyperpolarizability tensor in a solid-state sample. AU - Higginbotham, Andrew P AU - Cole, Jacqueline AU - Blood Forsythe, Martin AU - Hickstein, Daniel ID - 91 IS - 3 JF - Journal of Applied Physics TI - Identifying and evaluating organic nonlinear optical materials via molecular moments VL - 111 ER - TY - JOUR AB - In models of radiative–convective equilibrium it is known that convection can spontaneously aggregate into one single localized moist region if the domain is large enough. The large changes in the mean climate state and radiative fluxes accompanying this self-aggregation raise questions as to what simulations at lower resolutions with parameterized convection, in similar homogeneous geometries, should be expected to produce to be considered successful in mimicking a cloud-resolving model. The authors investigate this self-aggregation in a nonrotating, three-dimensional cloud-resolving model on a square domain without large-scale forcing. It is found that self-aggregation is sensitive not only to the domain size, but also to the horizontal resolution. With horizontally homogeneous initial conditions, convective aggregation only occurs on domains larger than about 200km and with resolutions coarser than about 2km in the model examined. The system exhibits hysteresis, so that with aggregated initial conditions, convection remains aggregated even at our finest resolution, 500m, as long as the domain is greater than 200–300km. The sensitivity of self-aggregation to resolution and domain size in this model is due to the sensitivity of the distribution of low clouds to these two parameters. Indeed, the mechanism responsible for the aggregation of convection is the dynamical response to the longwave radiative cooling from low clouds. Strong longwave cooling near cloud top in dry regions forces downward motion, which by continuity generates inflow near cloud top and near-surface outflow from dry regions. This circulation results in the net export of moist static energy from regions with low moist static energy, yielding a positive feedback. AU - Muller, Caroline J AU - Held, Isaac M. ID - 9142 IS - 8 JF - Journal of the Atmospheric Sciences KW - Atmospheric Science SN - 0022-4928 TI - Detailed investigation of the self-aggregation of convection in cloud-resolving simulations VL - 69 ER - TY - JOUR AB - The Arabidopsis thaliana central cell, the companion cell of the egg, undergoes DNA demethylation before fertilization, but the targeting preferences, mechanism, and biological significance of this process remain unclear. Here, we show that active DNA demethylation mediated by the DEMETER DNA glycosylase accounts for all of the demethylation in the central cell and preferentially targets small, AT-rich, and nucleosome-depleted euchromatic transposable elements. The vegetative cell, the companion cell of sperm, also undergoes DEMETER-dependent demethylation of similar sequences, and lack of DEMETER in vegetative cells causes reduced small RNA–directed DNA methylation of transposons in sperm. Our results demonstrate that demethylation in companion cells reinforces transposon methylation in plant gametes and likely contributes to stable silencing of transposable elements across generations. AU - Ibarra, Christian A. AU - Feng, Xiaoqi AU - Schoft, Vera K. AU - Hsieh, Tzung-Fu AU - Uzawa, Rie AU - Rodrigues, Jessica A. AU - Zemach, Assaf AU - Chumak, Nina AU - Machlicova, Adriana AU - Nishimura, Toshiro AU - Rojas, Denisse AU - Fischer, Robert L. AU - Tamaru, Hisashi AU - Zilberman, Daniel ID - 9451 IS - 6100 JF - Science SN - 0036-8075 TI - Active DNA demethylation in plant companion cells reinforces transposon methylation in gametes VL - 337 ER - TY - JOUR AB - The most well-studied function of DNA methylation in eukaryotic cells is the transcriptional silencing of genes and transposons. More recent results showed that many eukaryotes methylate the bodies of genes as well and that this methylation correlates with transcriptional activity rather than repression. The purpose of gene body methylation remains mysterious, but is potentially related to the histone variant H2A.Z. Studies in plants and animals have shown that the genome-wide distributions of H2A.Z and DNA methylation are strikingly anticorrelated. Furthermore, we and other investigators have shown that this relationship is likely to be the result of an ancient but unknown mechanism by which DNA methylation prevents the incorporation of H2A.Z. Recently, we discovered strong correlations between the presence of H2A.Z within gene bodies, the degree to which a gene's expression varies across tissue types or environmental conditions, and transcriptional misregulation in an h2a.z mutant. We propose that one basal function of gene body methylation is the establishment of constitutive expression patterns within housekeeping genes by excluding H2A.Z from their bodies. AU - Coleman-Derr, D. AU - Zilberman, Daniel ID - 9535 JF - Cold Spring Harbor Symposia on Quantitative Biology SN - 0091-7451 TI - DNA methylation, H2A.Z, and the regulation of constitutive expression VL - 77 ER - TY - JOUR AB - Due to the omnipresent risk of epidemics, insect societies have evolved sophisticated disease defences at the individual and colony level. An intriguing yet little understood phenomenon is that social contact to pathogen-exposed individuals reduces susceptibility of previously naive nestmates to this pathogen. We tested whether such social immunisation in Lasius ants against the entomopathogenic fungus Metarhizium anisopliae is based on active upregulation of the immune system of nestmates following contact to an infectious individual or passive protection via transfer of immune effectors among group members—that is, active versus passive immunisation. We found no evidence for involvement of passive immunisation via transfer of antimicrobials among colony members. Instead, intensive allogrooming behaviour between naive and pathogen-exposed ants before fungal conidia firmly attached to their cuticle suggested passage of the pathogen from the exposed individuals to their nestmates. By tracing fluorescence-labelled conidia we indeed detected frequent pathogen transfer to the nestmates, where they caused low-level infections as revealed by growth of small numbers of fungal colony forming units from their dissected body content. These infections rarely led to death, but instead promoted an enhanced ability to inhibit fungal growth and an active upregulation of immune genes involved in antifungal defences (defensin and prophenoloxidase, PPO). Contrarily, there was no upregulation of the gene cathepsin L, which is associated with antibacterial and antiviral defences, and we found no increased antibacterial activity of nestmates of fungus-exposed ants. This indicates that social immunisation after fungal exposure is specific, similar to recent findings for individual-level immune priming in invertebrates. Epidemiological modeling further suggests that active social immunisation is adaptive, as it leads to faster elimination of the disease and lower death rates than passive immunisation. Interestingly, humans have also utilised the protective effect of low-level infections to fight smallpox by intentional transfer of low pathogen doses (“variolation” or “inoculation”). AU - Konrad, Matthias AU - Vyleta, Meghan AU - Theis, Fabian AU - Stock, Miriam AU - Tragust, Simon AU - Klatt, Martina AU - Drescher, Verena AU - Marr, Carsten AU - Ugelvig, Line V AU - Cremer, Sylvia ID - 3242 IS - 4 JF - PLoS Biology TI - Social transfer of pathogenic fungus promotes active immunisation in ant colonies VL - 10 ER - TY - GEN AB - Due to the omnipresent risk of epidemics, insect societies have evolved sophisticated disease defences at the individual and colony level. An intriguing yet little understood phenomenon is that social contact to pathogen-exposed individuals reduces susceptibility of previously naive nestmates to this pathogen. We tested whether such social immunisation in Lasius ants against the entomopathogenic fungus Metarhizium anisopliae is based on active upregulation of the immune system of nestmates following contact to an infectious individual or passive protection via transfer of immune effectors among group members—that is, active versus passive immunisation. We found no evidence for involvement of passive immunisation via transfer of antimicrobials among colony members. Instead, intensive allogrooming behaviour between naive and pathogen-exposed ants before fungal conidia firmly attached to their cuticle suggested passage of the pathogen from the exposed individuals to their nestmates. By tracing fluorescence-labelled conidia we indeed detected frequent pathogen transfer to the nestmates, where they caused low-level infections as revealed by growth of small numbers of fungal colony forming units from their dissected body content. These infections rarely led to death, but instead promoted an enhanced ability to inhibit fungal growth and an active upregulation of immune genes involved in antifungal defences (defensin and prophenoloxidase, PPO). Contrarily, there was no upregulation of the gene cathepsin L, which is associated with antibacterial and antiviral defences, and we found no increased antibacterial activity of nestmates of fungus-exposed ants. This indicates that social immunisation after fungal exposure is specific, similar to recent findings for individual-level immune priming in invertebrates. Epidemiological modeling further suggests that active social immunisation is adaptive, as it leads to faster elimination of the disease and lower death rates than passive immunisation. Interestingly, humans have also utilised the protective effect of low-level infections to fight smallpox by intentional transfer of low pathogen doses (“variolation” or “inoculation”). AU - Konrad, Matthias AU - Vyleta, Meghan AU - Theis, Fabian AU - Stock, Miriam AU - Klatt, Martina AU - Drescher, Verena AU - Marr, Carsten AU - Ugelvig, Line V AU - Cremer, Sylvia ID - 9755 TI - Data from: Social transfer of pathogenic fungus promotes active immunisation in ant colonies ER - TY - GEN AB - We propose a two-step procedure for estimating multiple migration rates in an approximate Bayesian computation (ABC) framework, accounting for global nuisance parameters. The approach is not limited to migration, but generally of interest for inference problems with multiple parameters and a modular structure (e.g. independent sets of demes or loci). We condition on a known, but complex demographic model of a spatially subdivided population, motivated by the reintroduction of Alpine ibex (Capra ibex) into Switzerland. In the first step, the global parameters ancestral mutation rate and male mating skew have been estimated for the whole population in Aeschbacher et al. (Genetics 2012; 192: 1027). In the second step, we estimate in this study the migration rates independently for clusters of demes putatively connected by migration. For large clusters (many migration rates), ABC faces the problem of too many summary statistics. We therefore assess by simulation if estimation per pair of demes is a valid alternative. We find that the trade-off between reduced dimensionality for the pairwise estimation on the one hand and lower accuracy due to the assumption of pairwise independence on the other depends on the number of migration rates to be inferred: the accuracy of the pairwise approach increases with the number of parameters, relative to the joint estimation approach. To distinguish between low and zero migration, we perform ABC-type model comparison between a model with migration and one without. Applying the approach to microsatellite data from Alpine ibex, we find no evidence for substantial gene flow via migration, except for one pair of demes in one direction. AU - Aeschbacher, Simon AU - Futschik, Andreas AU - Beaumont, Mark ID - 9758 TI - Data from: Approximate Bayesian computation for modular inference problems with many parameters: the example of migration rates ER - TY - GEN AB - To fight infectious diseases, host immune defences are employed at multiple levels. Sanitary behaviour, such as pathogen avoidance and removal, acts as a first line of defence to prevent infection [1] before activation of the physiological immune system. Insect societies have evolved a wide range of collective hygiene measures and intensive health care towards pathogen-exposed group members [2]. One of the most common behaviours is allogrooming, in which nestmates remove infectious particles from the body surfaces of exposed individuals [3]. Here we show that, in invasive garden ants, grooming of fungus-exposed brood is effective beyond the sheer mechanical removal of fungal conidiospores as it also includes chemical disinfection through the application of poison produced by the ants themselves. Formic acid is the main active component of the poison. It inhibits fungal growth of conidiospores remaining on the brood surface after grooming and also those collected in the mouth of the grooming ant. This dual function is achieved by uptake of the poison droplet into the mouth through acidopore self-grooming and subsequent application onto the infectious brood via brood grooming. This extraordinary behaviour extends current understanding of grooming and the establishment of social immunity in insect societies. AU - Tragust, Simon AU - Mitteregger, Barbara AU - Barone, Vanessa AU - Konrad, Matthias AU - Ugelvig, Line V AU - Cremer, Sylvia ID - 9757 TI - Data from: Ants disinfect fungus-exposed brood by oral uptake and spread of their poison ER - TY - JOUR AB - In this paper we present a surprising example of a Cr unimodal map of an interval f:I→I whose number of periodic points Pn(f)=∣{x∈I:fnx=x}∣ grows faster than any ahead given sequence along a subsequence nk=3k. This example also shows that ‘non-flatness’ of critical points is necessary for the Martens–de Melo–van Strien theorem [M. Martens, W. de Melo and S. van Strien. Julia–Fatou–Sullivan theory for real one-dimensional dynamics. Acta Math.168(3–4) (1992), 273–318] to hold. AU - Kaloshin, Vadim AU - KOZLOVSKI, O. S. ID - 8504 IS - 1 JF - Ergodic Theory and Dynamical Systems KW - Applied Mathematics KW - General Mathematics SN - 0143-3857 TI - A Cr unimodal map with an arbitrary fast growth of the number of periodic points VL - 32 ER - TY - JOUR AB - We prove there are finitely many isometry classes of planar central configurations (also called relative equilibria) in the Newtonian 5-body problem, except perhaps if the 5-tuple of positive masses belongs to a given codimension 2 subvariety of the mass space. AU - Albouy, Alain AU - Kaloshin, Vadim ID - 8503 IS - 1 JF - Annals of Mathematics SN - 0003-486X TI - Finiteness of central configurations of five bodies in the plane VL - 176 ER - TY - JOUR AB - A subject of extensive study in evolutionary theory has been the issue of how neutral, redundant copies can be maintained in the genome for long periods of time. Concurrently, examples of adaptive gene duplications to various environmental conditions in different species have been described. At this point, it is too early to tell whether or not a substantial fraction of gene copies have initially achieved fixation by positive selection for increased dosage. Nevertheless, enough examples have accumulated in the literature that such a possibility should be considered. Here, I review the recent examples of adaptive gene duplications and make an attempt to draw generalizations on what types of genes may be particularly prone to be selected for under certain environmental conditions. The identification of copy-number variation in ecological field studies of species adapting to stressful or novel environmental conditions may improve our understanding of gene duplications as a mechanism of adaptation and its relevance to the long-term persistence of gene duplications. AU - Fyodor Kondrashov ID - 887 IS - 1749 JF - Proceedings of the Royal Society of London Series B Biological Sciences TI - Gene duplication as a mechanism of genomic adaptation to a changing environment VL - 279 ER - TY - JOUR AB - Diffusiophoretic motion of colloids and macromolecules under salt gradients exhibits a logarithmic-sensing, i.e. the particle velocity is proportional to the spatial gradient of the logarithm of the salt concentration, as VDP = DDP∇logc. Here we explore experimentally the implications of this log-sensing behavior, on the basis of a hydrogel microfluidic device allowing to build spatially and temporally controlled gradients. We first demonstrate that the non-linearity of the salt-taxis leads to a trapping of particles under concentration gradient oscillations via a rectification of the motion. As an alternative, we make use of the high sensitivity of diffusiophoretic migration to vanishing salt concentration due to the log-sensing: in a counter-intuitive way, a vanishing gradient can lead to measurable velocity provided that the solute concentration is low enough, thus keeping ∇c/c finite. We show that this leads to a strong segregation of particles in osmotic shock configuration, resulting from a step change of the salt concentration at the boundaries. These various phenomena are rationalized on the basis of a theoretical description for the time-dependent Smoluchowski equation for the colloidal density. AU - Palacci, Jérémie A AU - Cottin-Bizonne, Cécile AU - Ybert, Christophe AU - Bocquet, Lydéric ID - 9049 IS - 4 JF - Soft Matter SN - 1744-683X TI - Osmotic traps for colloids and macromolecules based on logarithmic sensing in salt taxis VL - 8 ER - TY - JOUR AB - We study theoretically the morphologies of biological tubes affected by various pathologies. When epithelial cells grow, the negative tension produced by their division provokes a buckling instability. Several shapes are investigated: varicose, dilated, sinuous, or sausagelike. They are all found in pathologies of tracheal, renal tubes, or arteries. The final shape depends crucially on the mechanical parameters of the tissues: Young's modulus, wall-to-lumen ratio, homeostatic pressure. We argue that since tissues must be in quasistatic mechanical equilibrium, abnormal shapes convey information as to what causes the pathology. We calculate a phase diagram of tubular instabilities which could be a helpful guide for investigating the underlying genetic regulation. AU - Hannezo, Edouard B AU - Prost, Jacques AU - Joanny, Jean ID - 922 IS - 1 JF - Physical Review Letters TI - Mechanical instabilities of biological tubes VL - 109 ER - TY - JOUR AB - EMBRYONIC FLOWER1 (EMF1) is a plant-specific gene crucial to Arabidopsis vegetative development. Loss of function mutants in the EMF1 gene mimic the phenotype caused by mutations in Polycomb Group protein (PcG) genes, which encode epigenetic repressors that regulate many aspects of eukaryotic development. In Arabidopsis, Polycomb Repressor Complex 2 (PRC2), made of PcG proteins, catalyzes trimethylation of lysine 27 on histone H3 (H3K27me3) and PRC1-like proteins catalyze H2AK119 ubiquitination. Despite functional similarity to PcG proteins, EMF1 lacks sequence homology with known PcG proteins; thus, its role in the PcG mechanism is unclear. To study the EMF1 functions and its mechanism of action, we performed genome-wide mapping of EMF1 binding and H3K27me3 modification sites in Arabidopsis seedlings. The EMF1 binding pattern is similar to that of H3K27me3 modification on the chromosomal and genic level. ChIPOTLe peak finding and clustering analyses both show that the highly trimethylated genes also have high enrichment levels of EMF1 binding, termed EMF1_K27 genes. EMF1 interacts with regulatory genes, which are silenced to allow vegetative growth, and with genes specifying cell fates during growth and differentiation. H3K27me3 marks not only these genes but also some genes that are involved in endosperm development and maternal effects. Transcriptome analysis, coupled with the H3K27me3 pattern, of EMF1_K27 genes in emf1 and PRC2 mutants showed that EMF1 represses gene activities via diverse mechanisms and plays a novel role in the PcG mechanism. AU - Kim, Sang Yeol AU - Lee, Jungeun AU - Eshed-Williams, Leor AU - Zilberman, Daniel AU - Sung, Z. Renee ID - 9499 IS - 3 JF - PLoS Genetics SN - 1553-7390 TI - EMF1 and PRC2 cooperate to repress key regulators of Arabidopsis development VL - 8 ER - TY - JOUR AB - The regulation of eukaryotic chromatin relies on interactions between many epigenetic factors, including histone modifications, DNA methylation, and the incorporation of histone variants. H2A.Z, one of the most conserved but enigmatic histone variants that is enriched at the transcriptional start sites of genes, has been implicated in a variety of chromosomal processes. Recently, we reported a genome-wide anticorrelation between H2A.Z and DNA methylation, an epigenetic hallmark of heterochromatin that has also been found in the bodies of active genes in plants and animals. Here, we investigate the basis of this anticorrelation using a novel h2a.z loss-of-function line in Arabidopsis thaliana. Through genome-wide bisulfite sequencing, we demonstrate that loss of H2A.Z in Arabidopsis has only a minor effect on the level or profile of DNA methylation in genes, and we propose that the global anticorrelation between DNA methylation and H2A.Z is primarily caused by the exclusion of H2A.Z from methylated DNA. RNA sequencing and genomic mapping of H2A.Z show that H2A.Z enrichment across gene bodies, rather than at the TSS, is correlated with lower transcription levels and higher measures of gene responsiveness. Loss of H2A.Z causes misregulation of many genes that are disproportionately associated with response to environmental and developmental stimuli. We propose that H2A.Z deposition in gene bodies promotes variability in levels and patterns of gene expression, and that a major function of genic DNA methylation is to exclude H2A.Z from constitutively expressed genes. AU - Coleman-Derr, Devin AU - Zilberman, Daniel ID - 9497 IS - 10 JF - PLoS Genetics SN - 1553-7390 TI - Deposition of histone variant H2A.Z within gene bodies regulates responsive genes VL - 8 ER - TY - JOUR AB - Accumulating evidence points toward diverse functions for plant chromatin. Remarkable progress has been made over the last few years in elucidating the mechanisms for a number of these functions. Activity of the histone demethylase IBM1 accurately targets DNA methylation to silent repeats and transposable elements, not to genes. A genetic screen uncovered the surprising role of H2A.Z-containing nucleosomes in sensing precise differences in ambient temperature and consequent gene regulation. Precise maintenance of chromosome number is assured by a histone modification that suppresses inappropriate DNA replication and by centromeric histone H3 regulation of chromosome segregation. Histones and noncoding RNAs regulate FLOWERING LOCUS C, the expression of which quantitatively measures the duration of cold exposure, functioning as memory of winter. These findings are a testament to the power of using plants to research chromatin organization, and demonstrate examples of how chromatin functions to achieve biological accuracy, precision, and memory. AU - Huff, Jason T. AU - Zilberman, Daniel ID - 9528 IS - 2 JF - Current Opinion in Genetics and Development SN - 0959-437X TI - Regulation of biological accuracy, precision, and memory by plant chromatin organization VL - 22 ER - TY - JOUR AB - Motivated by recent experiments on Ba3NiSb2O 9, we investigate possible quantum spin liquid ground states for spin S=1 Heisenberg models on the triangular lattice. We use variational Monte Carlo techniques to calculate the energies of microscopic spin liquid wave functions where spin is represented by three flavors of fermionic spinon operators. These energies are compared with the energies of various competing three-sublattice ordered states. Our approach shows that the antiferromagnetic Heisenberg model with biquadratic term and single-ion anisotropy does not have a low-temperature spin liquid phase. However, for an SU(3)-invariant model with sufficiently strong ring-exchange terms, we find a paired chiral quantum spin liquid with a Fermi surface of deconfined spinons that is stable against all types of ordering patterns we considered. We discuss the physics of this exotic spin liquid state in relation to the recent experiment and suggest new ways to test this scenario. AU - Bieri, Samuel AU - Maksym Serbyn AU - Senthil, Todadri S AU - Lee, Patrick ID - 966 IS - 22 JF - Physical Review B - Condensed Matter and Materials Physics TI - Paired chiral spin liquid with a Fermi surface in S=1 model on the triangular lattice VL - 86 ER - TY - JOUR AB - Little is known about the stability of trophic relationships in complex natural communities over evolutionary timescales. Here, we use sequence data from 18 nuclear loci to reconstruct and compare the intraspecific histories of major Pleistocene refugial populations in the Middle East, the Balkans and Iberia in a guild of four Chalcid parasitoids (Cecidostiba fungosa, Cecidostiba semifascia, Hobbya stenonota and Mesopolobus amaenus) all attacking Cynipid oak galls. We develop a likelihood method to numerically estimate models of divergence between three populations from multilocus data. We investigate the power of this framework on simulated data, and-using triplet alignments of intronic loci-quantify the support for all possible divergence relationships between refugial populations in the four parasitoids. Although an East to West order of population divergence has highest support in all but one species, we cannot rule out alternative population tree topologies. Comparing the estimated times of population splits between species, we find that one species, M. amaenus, has a significantly older history than the rest of the guild and must have arrived in central Europe at least one glacial cycle prior to other guild members. This suggests that although all four species may share a common origin in the East, they expanded westwards into Europe at different times. © 2012 Blackwell Publishing Ltd. AU - Lohse, Konrad AU - Barton, Nicholas H AU - Melika, George AU - Stone, Graham ID - 2968 IS - 18 JF - Molecular Ecology TI - A likelihood based comparison of population histories in a parasitoid guild VL - 21 ER - TY - GEN AB - Little is known about the stability of trophic relationships in complex natural communities over evolutionary timescales. Here, we use sequence data from 18 nuclear loci to reconstruct and compare the intraspecific histories of major Pleistocene refugial populations in the Middle East, the Balkans and Iberia in a guild of four Chalcid parasitoids (Cecidostiba fungosa, C. semifascia, Hobbya stenonota and Mesopolobus amaenus) all attacking Cynipid oak galls. We develop a likelihood method to numerically estimate models of divergence between three populations from multilocus data. We investigate the power of this framework on simulated data, and - using triplet alignments of intronic loci - quantify the support for all possible divergence relationships between refugial populations in the four parasitoids. Although an East to West order of population divergence has highest support in all but one species, we cannot rule out alternative population tree topologies. Comparing the estimated times of population splits between species, we find that one species, M. amaenus, has a significantly older history than the rest of the guild and must have arrived in central Europe at least one glacial cycle prior to other guild members. This suggests that although all four species may share a common origin in the East, they expanded westwards into Europe at different times. AU - Lohse, Konrad AU - Barton, Nicholas H AU - Stone, Graham AU - Melika, George ID - 13075 TI - Data from: A likelihood-based comparison of population histories in a parasitoid guild ER -