The potential for arms race and Red Queen coevolution in a protist host-parasite system

11 pages, 6 figures, supporting information http://onlinelibrary.wiley.com/doi/10.1002/ece3.1314/suppinfoEcology and Evolution published by John Wiley & Sons Ltd. The dynamics and consequences of host-parasite coevolution depend on the nature of host genotype-by-parasite genotype interactions (G × G) for host and parasite fitness. G × G with crossing reaction norms can yield cyclic dynamics of allele frequencies ("Red Queen" dynamics) while G × G where the variance among host genotypes differs between parasite genotypes results in selective sweeps ("arms race" dynamics). Here, we investigate the relative potential for arms race and Red Queen coevolution in a protist host-parasite system, the dinoflagellate Alexandrium minutum and its parasite Parvilucifera sinerae. We challenged nine different clones of A. minutum with 10 clones of P. sinerae in a fully factorial design and measured infection success and host and parasite fitness. Each host genotype was successfully infected by four to ten of the parasite genotypes. There were strong G × Gs for infection success, as well as both host and parasite fitness. About three quarters of the G × G variance components for host and parasite fitness were due to crossing reaction norms. There were no general costs of resistance or infectivity. We conclude that there is high potential for Red Queen dynamics in this host-parasite system. We investigate the relative potential for arms race and Red Queen coevolution in a protist host-parasite system by dissecting the nature of host geontype-by-parasite genotype interactions (G × G). G × Gs were mainly a result of crossing reaction norms, indicating high potential for Red Queen dynamics. © 2014 The AuthorsThis research was funded by the Crafoord Foundation (contract 2011:0882 to RF) and Spanish Ministry of Science and Innovation (project PARAL CTM2009-08399 to EG). L. Råberg was supported by a fellowship from the Swedish Research CouncilPeer Reviewe

The Genetic Basis of Natural Variation in Seed Size and Seed Number and Their Trade-Off Using Arabidopsis thaliana MAGIC Lines

Offspring number and size are key traits determining an individual’s fitness and a crop’s yield. Yet, extensive natural variation within species is observed for these traits. Such variation is typically explained by trade-offs between fecundity and quality, for which an optimal solution is environmentally dependent. Understanding the genetic basis of seed size and number, as well as any possible genetic constraints preventing the maximization of both, is crucial from both an evolutionary and applied perspective. We investigated the genetic basis of natural variation in seed size and number using a set of Arabidopsis thaliana multiparent advanced generation intercross (MAGIC) lines. We also tested whether life history affects seed size, number, and their trade-off. We found that both seed size and seed number are affected by a large number of mostly nonoverlapping QTL, suggesting that seed size and seed number can evolve independently. The allele that increases seed size at most identified QTL is from the same natural accession, indicating past occurrence of directional selection for seed size. Although a significant trade-off between seed size and number is observed, its expression depends on life-history characteristics, and generally explains little variance. We conclude that the trade-off between seed size and number might have a minor role in explaining the maintenance of variation in seed size and number, and that seed size could be a valid target for selection

Genomic Rearrangements in Arabidopsis Considered as Quantitative Traits.

To understand the population genetics of structural variants and their effects on phenotypes, we developed an approach to mapping structural variants that segregate in a population sequenced at low coverage. We avoid calling structural variants directly. Instead, the evidence for a potential structural variant at a locus is indicated by variation in the counts of short-reads that map anomalously to that locus. These structural variant traits are treated as quantitative traits and mapped genetically, analogously to a gene expression study. Association between a structural variant trait at one locus, and genotypes at a distant locus indicate the origin and target of a transposition. Using ultra-low-coverage (0.3×) population sequence data from 488 recombinant inbred Arabidopsis thaliana genomes, we identified 6502 segregating structural variants. Remarkably, 25% of these were transpositions. While many structural variants cannot be delineated precisely, we validated 83% of 44 predicted transposition breakpoints by polymerase chain reaction. We show that specific structural variants may be causative for quantitative trait loci for germination and resistance to infection by the fungus Albugo laibachii, isolate Nc14. Further we show that the phenotypic heritability attributable to read-mapping anomalies differs from, and, in the case of time to germination and bolting, exceeds that due to standard genetic variation. Genes within structural variants are also more likely to be silenced or dysregulated. This approach complements the prevalent strategy of structural variant discovery in fewer individuals sequenced at high coverage. It is generally applicable to large populations sequenced at low-coverage, and is particularly suited to mapping transpositions

The evolution of transmission mode

This article reviews research on the evolutionary mechanisms leading to different transmission modes. Such modes are often under genetic control of the host or the pathogen, and often in conflict with each other via trade-offs. Transmission modes may vary among pathogen strains and among host populations. Evolutionary changes in transmission mode have been inferred through experimental and phylogenetic studies, including changes in transmission associated with host-shifts and with evolution of the unusually complex life cycles of many parasites. Understanding the forces that determine the evolution of particular transmission modes presents a fascinating medley of problems for which there is a lack of good data and often a lack of conceptual understanding or appropriate methodologies. Our best information comes from studies that have been focused on the vertical vs. horizontal transmission dichotomy. With other kinds of transitions, theoretical approaches combining epidemiology and population genetics are providing guidelines for determining when and how rapidly new transmission modes may evolve, but these are still in need of empirical investigation and application to particular cases. Obtaining such knowledge is a matter of urgency in relation to extant disease threats

Bioinformatics tools and database resources for systems genetics analysis in mice—a short review and an evaluation of future needs

During a meeting of the SYSGENET working group ‘Bioinformatics’, currently available software tools and databases for systems genetics in mice were reviewed and the needs for future developments discussed. The group evaluated interoperability and performed initial feasibility studies. To aid future compatibility of software and exchange of already developed software modules, a strong recommendation was made by the group to integrate HAPPY and R/qtl analysis toolboxes, GeneNetwork and XGAP database platforms, and TIQS and xQTL processing platforms. R should be used as the principal computer language for QTL data analysis in all platforms and a ‘cloud’ should be used for software dissemination to the community. Furthermore, the working group recommended that all data models and software source code should be made visible in public repositories to allow a coordinated effort on the use of common data structures and file formats

Antecedents to value diminution: A dyadic perspective

© 2016, © The Author(s) 2016. The purpose of this article is to identify the antecedents of diminished value in business-to-business exchange. There is only a limited amount of research on value destruction in the context of service-dominant (S-D) logic and, to the best of our knowledge, no dyadic studies. From a business perspective, awareness of factors that have the potential to impede value creation will enable relationship partners to increase mutual value realization. The article examines the accuracy of the term ‘value co-destruction’ as a blanket description for interaction that results in value reduction, and proposes that, in many instances, ‘value diminution’ may be more appropriate. The study adopts an exploratory, qualitative approach. One-to-one interviews are conducted with clients and their creative agencies. The results suggest that diminished value outcomes are caused by resource deficiencies and resource misuse by both relational partners, separately and jointly. We propose a model of five higher-order antecedents of value diminution: absence of trust, inadequate communication, power/dependence imbalance, inadequate coordination and inadequate human capital

Dissecting the Genetic Architecture of Host–Pathogen Specificity

International audienc

Tracing Personalized Health Curves during Infections

By concentrating on the relationship between health and microbe number over the course of infections, most pathogenic and mutualistic infections can be summarized by a small alphabet of curves, which has implications not only for basic research but for how we might treat patients

An experimental study of executive function and social impairment in Cornelia de Lange syndrome

Background Extreme shyness and social anxiety is reported to be characteristic of adolescents and adults with Cornelia de Lange syndrome (CdLS); however, the nature of these characteristics is not well documented. In this study, we develop and apply an experimental assessment of social anxiety in a group of adolescents and adults with CdLS to determine the nature of the social difficulties and whether they are related to impairments in executive functioning. Methods A familiar and unfamiliar examiner separately engaged in socially demanding tasks comprising three experimental conditions with a group of individuals with CdLS (n = 25; % male = 44; mean age = 22.16; SD = 8.81) and a comparable group of individuals with Down syndrome (DS; n = 20; % male = 35; mean age = 24.35; SD = 5.97). Behaviours indicative of social anxiety were coded. The Behavior Rating Inventory of Executive Function-Preschool version, an informant measure of executive function, was completed by participants’ caregivers. Results Significantly less verbalisation was observed in the CdLS group than the DS group in conditions requiring the initiation of speech. In the CdLS group, impairments in verbalisation were not associated with a greater degree of intellectual disability but were significantly correlated with impairments in both planning and working memory. This association was not evident in the DS group. Conclusions Adolescents and adults with CdLS have a specific difficulty with the initiation of speech when social demands are placed upon them. This impairment in verbalisation may be underpinned by specific cognitive deficits, although further research is needed to investigate this fully

Contributions of phonological and verbal working memory to language development in adolescents with fragile X syndrome

Fragile X syndrome (FXS) is the most common inherited cause of intellectual disability. Although language delays are frequently observed in FXS, neither the longitudinal course of language development nor its cognitive predictors are well understood. The present study investigated whether phonological and working memory skills are predictive of growth in vocabulary and syntax in individuals with FXS during adolescence. Forty-four individuals with FXS (mean age = 12.61 years) completed assessments of phonological memory (nonword repetition and forward digit recall), verbal working memory (backward digit recall), vocabulary, syntax, and nonverbal cognition. Vocabulary and syntax skills were reassessed at a 2-year follow-up. In a series of analyses that controlled for nonverbal cognitive ability and severity of autism symptoms, the relative contributions of phonological and working memory to language change over time were investigated. These relationships were examined separately for boys and girls. In boys with FXS, phonological memory significantly predicted gains in vocabulary and syntax skills. Further, verbal working memory was uniquely associated with vocabulary gains among boys. In girls with FXS, phonological and working memory skills showed no relationship with language change across the 2-year time period. Our findings indicate that, for adolescent boys with FXS, acquisition of vocabulary and syntax may be constrained by the ability to maintain and manipulate phonological representations online. Implications for the identification and treatment of language disorders in this population are discussed. The present study is the first to identify specific cognitive mechanisms contributing to language growth over time in individuals with FXS