1,077 research outputs found

    Greater sexual reproduction contributes to differences in demography of invasive plants and their noninvasive relatives

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    An understanding of the demographic processes contributing to invasions would improve our mechanistic understanding of the invasion process and improve the efficiency of prevention and control efforts. However, field comparisons of the demography of invasive and noninvasive species have not previously been conducted. We compared the in situ demography of 17 introduced plant species in St. Louis, Missouri, USA, to contrast the demographic patterns of invasive species with their less invasive relatives across a broad sample of angiosperms. Using herbarium records to estimate spread rates, we found higher maximum spread rates in the landscape for species classified a priori as invasive than for noninvasive introduced species, suggesting that expert classifications are an accurate reflection of invasion rate. Across 17 species, projected population growth was not significantly greater in invasive than in noninvasive introduced species. Among five taxonomic pairs of close relatives, however, four of the invasive species had higher projected population growth rates compared with their noninvasive relative. A Life Table Response Experiment suggested that the greater projected population growth rate of some invasive species relative to their noninvasive relatives was primarily a result of sexual reproduction. The greater sexual reproduction of invasive species is consistent with invaders having a life history strategy more reliant on fecundity than survival and is consistent with a large role of propagule pressure in invasion. Sexual reproduction is a key demographic correlate of invasiveness, suggesting that local processes influencing sexual reproduction, such as enemy escape, might be of general importance. However, the weak correlation of projected population growth with spread rates in the landscape suggests that regional processes, such as dispersal, may be equally important in determining invasion rate

    Symbioses with nitrogen-fixing bacteria:nodulation and phylogenetic data across legume genera

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    How species interactions shape global biodiversity and influence diversification is a central - but also data-hungry - question in evolutionary ecology. Microbially-based mutualisms are widespread and could cause diversification by ameliorating stress and thus allowing organisms to colonize and adapt to otherwise unsuitable habitats. Yet the role of these interactions in generating species diversity has received limited attention, especially across large taxonomic groups. In the massive angiosperm family Leguminosae, plants often associate with root-nodulating bacteria that ameliorate nutrient stress by fixing atmospheric nitrogen. These symbioses are ecologically-important interactions, influencing community assembly, diversity, and succession, contributing ~100-290 million tons of N annually to natural ecosystems, and enhancing growth of agronomically-important forage and crop plants worldwide. In recent work attempting to determine whether mutualism with N-fixing bacteria led to increased diversification across legumes, we were unable to definitively resolve the relationship between diversification and nodulation. We did, however, succeed in compiling a very large searchable, analysis-ready database of nodulation data for 749 legume genera (98% of Leguminosae genera; LPWG 2017), which, along with associated phylogenetic information, will provide a valuable resource for future work addressing this question and others. For each legume genus, we provide information about the species richness, frequency of nodulation, subfamily association, and topological correspondence with an additional data set of 100 phylogenetic trees curated for database compatibility. We found 386 legume genera were confirmed nodulators (i.e., all species examined for nodulation nodulated), 116 were non-nodulating, 4 were variable (i.e., containing both confirmed nodulators and confirmed non-nodulators), and 243 had not been examined for nodulation in published studies. Interestingly, data exploration revealed that nodulating legume genera are ~3× more species-rich than non-nodulating genera, but we did not find evidence that this difference in diversity was due to differences in net diversification rate. Our metadata file describes in more detail the structure of these data that provide a foundational resource for future work as more nodulation data become available, and as greater phylogenetic resolution of this ca. 19,500-species family comes into focus. This article is protected by copyright. All rights reserved.</p

    Becoming-Bertha: virtual difference and repetition in postcolonial 'writing back', a Deleuzian reading of Jean Rhys’s Wide Sargasso Sea

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    Critical responses to Wide Sargasso Sea have seized upon Rhys’s novel as an exemplary model of writing back. Looking beyond the actual repetitions which recall Brontë’s text, I explore Rhys’s novel as an expression of virtual difference and becomings that exemplify Deleuze’s three syntheses of time. Elaborating the processes of becoming that Deleuze’s third synthesis depicts, Antoinette’s fate emerges not as a violence against an original identity. Rather, what the reader witnesses is a series of becomings or masks, some of which are validated, some of which are not, and it is in the rejection of certain masks, forcing Antoinette to become-Bertha, that the greatest violence lies

    Mekanisme pencairan dana pembiayaan mudharabah dengan agunan cash collateral : studi kasus pada KSPPS Arthamadina Banyuputih-Batang

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    Koperasi simpan pinjam dan pembiayaan syariah merupakan koperasi yang kegiatan usahanya meliputi pinjaman, simpanan, dan pembiayaan yang pengoprasiannya sesuai dengan perinsip syariah dan juga terdapat kegiatan pengelolaan zakat, infaq/sodakoh, dan wakaf. KSPPS Arthamadina dalam menyalurkan danannya menggunakan akad mudharabah atau akad kerja sama antara shohibul maal dan mudharib, kspps arthamadina juga menyediakan pembiayaan dengan agunan cast collateral untuk mempermudah anggota atau calon anggotanya yang akan mengajukan pembiayaan tetapi tidak mempunyai fix asset. Adapun rumusan masalah yang dalam penelitian ini, adalah bagaimana mekanisme pencairan dana pembiayaan dan apa saja yang dijadikan pertimbangan dalam melakukan pembiayaan dengan agunan cast collateral di KSPPS Arthamadina. Penelitian ini menggunakan metode kualitatif, dengan menggunakan pendekatan deskritif dengan berusaha mengambarkan hasil penelitian yang apa adanya. Teknik pengumpulan data dengan observasi, wawancara, dan dokumentasi. KSPPS Arthamadina adalah tempat yang dijadikan penelitian yang daerah kerjanya di Kabupaten Batang, lebih tepatnya di Jl. Lokojoyo Km. 1 Banyuputih, Batang 51271. Dari hasil penelitian KSPPS Arthamadina belum sepenuhnya menggunakan prinsip syariah dikarenakan di KSPPS Arthamadina masih menggunakan persentase dalam bagi hasilnya. Pembiayaan dengan agunan cast collateral juga diterapkan untuk memberikan kemudahan, kesejahteraan, dan membantu anggotanya yang tidak memiliki agunan fix asset tetapi masih dapat melakukan pembiayaan dengan plafon yang kecil

    Leading through agonistic conflict: Contested sense-making in national political arenas

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    This article examines the social processes of political leadership in situations of contest and conflict, taking place within a key and long-established democratic institution, the UK Parliament. The empirical focus is on leadership in House of Commons select committees, which are concerned with holding the government to account. Headlines and media scrutiny, combined with internal challenge from the cross-party mix of politicians on the committees and a range of external stakeholders, create leadership challenges for committee chairs. The study is of two committee inquiries led by the same committee chair, which occurred concurrently and in real time, thereby providing a rare comparative study of leadership through the same leader at the same time but with different leadership challenges. Rather than shying away from conflict, as does much of the leadership literature, this research highlights how leaders who actively engage in challenge and conflict can build a degree of shared purpose among diverse groups of stakeholders. It examines and combines, in theory elaboration, two theories relevant to understanding these leadership processes: agonistic pluralism with its role in creating respectful conflictual consensus, and the theory of sense-making and sense-giving. The two cases (the two inquiries) had different trajectories and reveal how the chair recognised and dealt with conflict to achieve sense-making outcomes across divergent interests and across political parties. There are implications not only for understanding political leadership but also more widely for leadership where there are diverse and sometimes conflicting interests

    LoCuSS: First Results from Strong-lensing Analysis of 20 Massive Galaxy Clusters at z~0.2

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    We present a statistical analysis of a sample of 20 strong lensing clusters drawn from the Local Cluster Substructure Survey (LoCuSS), based on high resolution Hubble Space Telescope imaging of the cluster cores and follow-up spectroscopic observations using the Keck-I telescope. We use detailed parameterized models of the mass distribution in the cluster cores, to measure the total cluster mass and fraction of that mass associated with substructures within R<250kpc.These measurements are compared with the distribution of baryons in the cores, as traced by the old stellar populations and the X-ray emitting intracluster medium. Our main results include: (i) the distribution of Einstein radii is log-normal, with a peak and 1sigma width of =1.16+/-0.28; (ii) we detect an X-ray/lensing mass discrepancy of =1.3 at 3 sigma significance -- clusters with larger substructure fractions displaying greater mass discrepancies, and thus greater departures from hydrostatic equilibrium; (iii) cluster substructure fraction is also correlated with the slope of the gas density profile on small scales, implying a connection between cluster-cluster mergers and gas cooling. Overall our results are consistent with the view that cluster-cluster mergers play a prominent role in shaping the properties of cluster cores, in particular causing departures from hydrostatic equilibrium, and possibly disturbing cool cores. Our results do not support recent claims that large Einstein radius clusters present a challenge to the CDM paradigm.Comment: 28 pages, 14 figures, accepted for publication in MNRAS, replaced with accepted versio

    Land Use and Pollinator Dependency Drives Global Patterns of Pollen Limitation in the Anthropocene

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    Land use change, by disrupting the co-evolved interactions between plants and their pollinators, could be causing plant reproduction to be limited by pollen supply. Using a phylogenetically controlled meta-analysis on over 2200 experimental studies and more than 1200 wild plants, we ask if land use intensification is causing plant reproduction to be pollen limited at global scales. Here we report that plants reliant on pollinators in urban settings are more pollen limited than similarly pollinator-reliant plants in other landscapes. Plants functionally specialized on bee pollinators are more pollen limited in natural than managed vegetation, but the reverse is true for plants pollinated exclusively by a non-bee functional group or those pollinated by multiple functional groups. Plants ecologically specialized on a single pollinator taxon were extremely pollen limited across land use types. These results suggest that while urbanization intensifies pollen limitation, ecologically and functionally specialized plants are at risk of pollen limitation across land use categories

    The Atacama Cosmology Telescope: Cosmology from Galaxy Clusters Detected via the Sunyaev-Zel'dovich Effect

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    We present constraints on cosmological parameters based on a sample of Sunyaev-Zel'dovich-selected galaxy clusters detected in a millimeter-wave survey by the Atacama Cosmology Telescope. The cluster sample used in this analysis consists of 9 optically-confirmed high-mass clusters comprising the high-significance end of the total cluster sample identified in 455 square degrees of sky surveyed during 2008 at 148 GHz. We focus on the most massive systems to reduce the degeneracy between unknown cluster astrophysics and cosmology derived from SZ surveys. We describe the scaling relation between cluster mass and SZ signal with a 4-parameter fit. Marginalizing over the values of the parameters in this fit with conservative priors gives sigma_8 = 0.851 +/- 0.115 and w = -1.14 +/- 0.35 for a spatially-flat wCDM cosmological model with WMAP 7-year priors on cosmological parameters. This gives a modest improvement in statistical uncertainty over WMAP 7-year constraints alone. Fixing the scaling relation between cluster mass and SZ signal to a fiducial relation obtained from numerical simulations and calibrated by X-ray observations, we find sigma_8 = 0.821 +/- 0.044 and w = -1.05 +/- 0.20. These results are consistent with constraints from WMAP 7 plus baryon acoustic oscillations plus type Ia supernoava which give sigma_8 = 0.802 +/- 0.038 and w = -0.98 +/- 0.053. A stacking analysis of the clusters in this sample compared to clusters simulated assuming the fiducial model also shows good agreement. These results suggest that, given the sample of clusters used here, both the astrophysics of massive clusters and the cosmological parameters derived from them are broadly consistent with current models.Comment: 12 pages, 7 figures. Submitted to Ap

    Glopl, a global data base on pollen limitation of plant reproduction

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    Plant reproduction relies on transfer of pollen from anthers to stigmas, and the majority of flowering plants depend on biotic or abiotic agents for this transfer. A key metric for characterizing if pollen receipt is insufficient for reproduction is pollen limitation, which is assessed by pollen supplementation experiments. In a pollen supplementation experiment, fruit or seed production by flowers exposed to natural pollination is compared to that following hand pollination either by pollen supplementation (i.e. manual outcross pollen addition without bagging) or manual outcrossing of bagged flowers, which excludes natural pollination. The GloPL database brings together data from 2969 unique pollen supplementation experiments reported in 927 publications published from 1981 to 2015, allowing assessment of the strength and variability of pollen limitation in 1265 wild plant species across all biomes and geographic regions globally. The GloPL database will be updated and curated with the aim of enabling the continued study of pollen limitation in natural ecosystems and highlighting significant gaps in our understanding of pollen limitation.<p>Correction in: Scientific Data, vol. 6, article number: 2. DOI: 10.1038/s41597-018-0006-1</p
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