1,397 research outputs found

    Time-Calibrated Phylogenies of Hummingbirds and Hummingbird-Pollinated Plants Reject a Hypothesis of Diffuse Co-Evolution

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    Neotropical ecosystems house levels of species diversity that are unmatched by any other region on Earth. One hypothesis to explain this celebrated diversity invokes a model of biotic interactions in which interspecific interactions drive diversification of two (or more) lineages. When the impact of the interaction on diversification is reciprocal, diversification of the lineages should be contemporaneous. Although past studies have provided evidence needed to test alternative models of diversification such as those involving abiotic factors (e.g., Andean uplift, shifting climatological regimes), tests of the biotic model have been stymied by lack of evolutionary time scale for symbiotic partners. In this study, we infer timescales for diversification of hummingbirds and a species-rich plant lineage that is ~50% hummingbird pollinated, Ruellia (Acanthaceae). Results demonstrate that hummingbirds originated about 20 million years before New World Ruellia and that all but one major hummingbird clade was extant before the plant group originated. Thus, the classic model of “diffuse co-evolution” between hummingbirds and this group of plants is rejected by our data. However, together with the observation that the Neotropical clade of Ruellia (~350 species) is far more species rich than its Old World sister group (~75 species), our results are consistent with the hypothesis that plant diversification in the Neotropics has been facilitated in part by a pre-existing diversity of hummingbirds. This hypothesis may find support in other lineages of Neotropical plants that similarly exhibit asymmetrical partitioning of species diversity in the Paleo- vs. Neotropics

    Nelsonioideae (Lamiales: Acanthaceae): Revision of Genera and Catalog of Species

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    A taxonomic account of Acanthaceae subfamily Nelsonioideae based on morphological and phylogenetic data treats five genera with 172 species: Anisosepalum (3), Elytraria (21), Nelsonia (2), Saintpauliopsis (1), and Staurogyne (145). Two other currently recognized genera, Gynocraterium and Ophiorrhiziphyllon, are included within Staurogyne, and the new combinations, Staurogyne guianensis and S. macrobotrya, are proposed. Probable apomorphic and other diagnostic macro- and micromorphological characters are discussed relative to the subfamily and genera. Characters of the inflorescence, androecium (especially pollen), and seed show important phylogenetic and diagnostic signal. A key to genera, generic descriptions and discussions, illustrations, and distribution maps are provided. Lists of currently recognized species for each genus include synonymies and distributions by country

    Phylogeny of Dyschoriste (Acanthaceae)

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    The pantropical and poorly known genus Dyschoriste (Acanthaceae) is sister to Strobilanthopsis within subtribe Petalidiinae. The present study included 38 accessions of 28 species as sources of DNA data for one nuclear (nrITS) and four chloroplast (intergenic spacers: psbA-trnH, trnS-trnG, ndhF-rpl32, rpl32- trnL(uag)) regions to provide an estimate of the phylogeny of the genus. We found that Dyschoriste is strongly supported as monophyletic inclusive of Apassalus, Chaetacanthus, and Sautiera. Within Dyschoriste, three geographically cohesive lineages were recovered with moderate to strong support: a mainland African clade, a Caribbean and southeastern United States clade, and a South and Central America clade. A third New World clade composed of accessions from the south central through southwestern US to Mexico is weakly supported and corresponds to the D. linearis species complex recognized by previous researchers (six of the ten taxa putatively part of this complex were sampled). A second Old World clade unites taxa from across the Old World tropics (mainland Africa, Madagascar and southeast Asia). Some aspects of relationships among these main clades were unresolved or not strongly supported, and two Old World taxa, south Asian D. dalzellii and the wide-ranging D. nagchana, were not placed with confidence in any of these clades. The simplest explanation for the current distribution of the genus is that there was a single dispersal event of Dyschoriste from the Old to the New World, with a subsequent radiation in the New World

    New Species, New Combinations and New Synonymies Towards a Treatment of Acanthaceae for the Manual de Plantas de Costa Rica

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    In preparation for the publication of the Manual de Plantas de Costa Rica, new species, names, combinations, and synonymies are provided in six genera of Acanthaceae: Anisacanthus, Chamaeranthemum, Dicliptera, Justicia, Ruellia and Stenostephanus. The new species are A. grace-woodiae, J. altior, J. lithophila and S. chavesii. A new name at the species level, R. leonardiana, is provided for R. tubiflora var. hirsuta. With Habracanthus, Hansteinia, Kalbreyeriella and Razisea being subsumed within Stenostephanus, the new combinations S. blepharorhachis, S. citrinus, S. leiorhachis (= Razisea spicata non S. spicatus), S. strictus, S. ventricosus, S. villosus and S. wilburii are formalized. Seven new synonymies are presented for species of Chamaeranthemum, Dicliptera, Justicia and Stenostephanus, as well as lectotypifications in the first and latter two genera

    Seroprevalence of Epstein-Barr Virus Infection in U.S. Children Ages 6-19, 2003-2010

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    Background:Epstein-Barr virus (EBV) is a common herpesvirus linked to infectious mononucleosis and multiple cancers. There are no national estimates of EBV seroprevalence in the United States. Our objective was to estimate the overall prevalence and sociodemographic predictors of EBV among U.S. children and adolescents aged 6-19.Methods:We calculated prevalence estimates and prevalence ratios for EBV seroprevalence using data from the 2003-2010 U.S. National Health and Nutrition Examination Survey (NHANES) for children aged 6-19 (n = 8417). Poisson regression was used to calculate multivariable-adjusted prevalence ratios across subgroup categories (sex, race/ethnicity, parental education, household income, household size, foreign-born, BMI, and household smoking).Findings:Overall EBV seroprevalence was 66.5% (95% CI 64.3%-68.7%.). Seroprevalence increased with age, ranging from 54.1% (95% CI 50.2%-57.9%) for 6-8 year olds to 82.9% (95% CI 80.0%-85.9%) for 18-19 year olds. Females had slightly higher seroprevalence (68.9%, 95% CI 66.3%-71.6%) compared to males (64.2%, 95% CI 61.7%-66.8%). Seroprevalence was substantially higher for Mexican-Americans (85.4%, 95% CI 83.1%-87.8%) and Non-Hispanic Blacks (83.1%, 95% CI 81.1%-85.1%) than Non-Hispanic Whites (56.9%, 95% CI 54.1%-59.8%). Large differences were also seen by family income, with children in the lowest income quartile having 81.0% (95% CI 77.6%-84.5%) seroprevalence compared to 53.9% (95% CI 50.5%-57.3%) in the highest income quartile, with similar results for parental education level. These results were not explained by household size, BMI, or parental smoking. Among those who were seropositive, EBV antibody titers were significantly higher for females, Non-Hispanic Blacks and Mexican-Americans, with no association found for socioeconomic factors.Conclusions:In the first nationally representative U.S. estimates, we found substantial socioeconomic and race/ethnic differences in the seroprevalence of EBV across all ages for U.S. children and adolescents. These estimates can help researchers and clinicians identify groups most at risk, inform research on EBV-cancer etiology, and motivate potential vaccine development

    Lower thermospheric nitric oxide concentrations derived from WINDII observations of the green nightglow continuum at 553.1 nm

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    International audienceVertical profiles of nitric oxide in the altitude range 90 to 105 km are derived from 553 nm nightglow continuum measurements made with the Wind Imaging Interferometer (WINDII) on the Upper Atmosphere Research Satellite (UARS). The profiles are derived under the assumption that the continuum emission is due entirely to the NO+O air afterglow reaction. Vertical profiles of the atomic oxygen density, which are required to determine the nitric oxide concentrations, are derived from coordinated WINDII measurements of the atomic oxygen OI 557.7 nm nightglow emission. Data coverage for local solar times ranging from 20 h to 04 h, and latitudes ranging from 42°S to 42°N, is achieved by zonally averaging and binning data obtained on 18 nights during a two-month period extending from mid-November 1992 until mid-January 1993. The derived nitric oxide concentrations are significantly smaller than those obtained from rocket measurements of the airglow continuum but they do compare well with model expectations and nitric oxide densities measured using the resonance fluorescence technique on the Solar Mesosphere Explorer satellite. The near-global coverage of the WINDII observations and the similarities to the nitric oxide global morphology established from other satellite measurements strongly suggests that the NO+O reaction is the major source of the continuum near 553 nm and that there is no compelling reason to invoke additional sources of continuum emission in this immediate spectral region

    Quality of Relationships with Parents and Friends in Adolescence Predicts Metabolic Risk in Young Adulthood

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    Objective: This study was designed to examine whether family and peer relationships in adolescence predict the emergence of metabolic risk factors in young adulthood. Method: Participants from a large, nationally representative cohort study (N = 11,617 for these analyses) reported on their relationship experiences with parents and close friends during adolescence. Fourteen years later, interviewers collected blood samples, as well as anthropometric and blood pressure measurements. Blood samples were analyzed for HbA1c. Results: Ordered logistic regressions revealed that for females, supportive parent–child relationships and close male friendships in adolescence were associated with reduced odds of having elevated metabolic risk markers in young adulthood. These effects remained significant even after controlling for baseline measures of body mass index (BMI) and health and demographic covariates. The protective effects of close relationships were not significant for males, however. Exploratory analyses with 2-parent families revealed that supportive father–child relationships were especially protective for females. Conclusions: These findings suggest that, for females, close and supportive relationships with parents and male friends in adolescence may reduce the risk of metabolic dysregulation in adulthood
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