8 research outputs found
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Geographic Life History Differences Predict Genomic Divergence Better than Mitochondrial Barcodes or Phenotype
Species diversity can be inferred using multiple data types, however, results based on genetic data can be at odds with patterns of phenotypic variation. Tiger beetles of the Cicindelidia politula (LeConte, 1875) species complex have been taxonomically problematic due to extreme phenotypic variation within and between populations. To better understand the biology and taxonomy of this group, we used mtDNA genealogies and multilocus nuclear analyses of 34,921 SNPs to elucidate its evolutionary history and evaluate the validity of phenotypically circumscribed species and subspecies. Genetic analyses recovered two divergent species that are also ecologically distinct, based on adult life history. These patterns are incongruous with the phenotypic variation that informed prior taxonomy, and most subspecies were not supported as distinct evolutionary lineages. One of the nominal subspecies was found to be a cryptic species; consequently, we elevate C. p. laetipennis (Horn, 1913) to a full species. Although nuclear and mtDNA datasets recovered broadly similar evolutionary units, mito-nuclear discordance was more common than expected, being observed between nearly all geographically overlapping taxonomic pairs. Additionally, a pattern of ‘mitochondrial displacement’ was observed, where mitochondria from one species unidirectionally displace others. Overall, we found that geographically associated life history factors better predict genomic divergence than phenotype and mitochondrial genealogies, and consequently taxon identifications based on mtDNA (e.g., DNA barcodes) may be misleading
Unifying systematics and taxonomy: Nomenclatural changes to Nearctic tiger beetles (Coleoptera: Carabidae: Cicindelinae) based on phylogenetics, morphology and life history
The taxonomy of Nearctic tiger beetles (Coleoptera: Carabidae: Cicindelinae) is reviewed in light of modern systematics research. Despite decades of published molecular phylogenies, the taxonomic nomenclature has not been formally updated since the 1950s. We generated a maximum likelihood phylogenetic tree based on three mitochondrial gene fragments (16S, COX3 and CytB) to address the placement of Nearctic taxa that were not included in recent studies; these species were historically contained within Cylindera Westwood, 1831, a polyphyletic genus. Here we describe Parvindela Duran and Gough, new genus, and propose 20 new combinations based on a plurality of data, including our topology, prior molecular phylogenetic studies, morphology and ecology: Apterodela unipunctata (Fabricius, 1775) new combination; Brasiella praecisa (Bates, 1890) new combination; Brasiella viridisticta (Bates, 1881) new combination; Cicindela amargosae (Dahl, 1939) new combination; Cicindela senilis (G. Horn, 1866) new combination; Cicindela willistoni (LeConte, 1879) new combination; Eunota californica (Menetries, 1883) new combination; Eunota circumpicta (LaFerte, 1841) new combination; Eunota fulgoris (Casey, 1913) new combination; Eunota gabbii (G. Horn, 1866) new combination; Eunota pamphila (LeConte, 1873) new combination; Eunota praetextata (LeConte, 1854) new combination; Eunota severa (LaFerte, 1841) new combination; Eunota striga (LeConte, 1875) new combination; Parvindela debilis (Bates, 1890) new combination; Parvindela celeripes (LeConte, 1848) new combination; Parvindela cursitans (LeConte, 1860) new combination; Parvindela terricola (Say, 1824) new combination; Parvindela nephelota (Bates, 1882) new combination; Parvindela lunalonga (Schaupp, 1884) new combination
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Late Holocene Historical Ecology: The Timing of Vertebrate Extirpation on Crooked Island, Commonwealth of The Bahamas
Hematopoietic Fas Deficiency Does Not Affect Experimental Atherosclerotic Lesion Formation despite Inducing a Proatherogenic State
The Fas death receptor (CD95) is expressed on macrophages, smooth muscle cells, and T cells within atherosclerotic lesions. Given the dual roles of Fas in both apoptotic and nonapoptotic signaling, the aim of the present study was to test the effect of hematopoietic Fas deficiency on experimental atherosclerosis in low-density lipoprotein receptor-null mice (Ldlr−/−). Bone marrow from Fas−/− mice was used to reconstitute irradiated Ldlr−/− mice as a model for atherosclerosis. After 16 weeks on an 0.5% cholesterol diet, no differences were noted in brachiocephalic artery lesion size, cellularity, or vessel wall apoptosis. However, Ldlr−/− mice reconstituted with Fas−/− hematopoietic cells had elevated hyperlipidemia [80% increase, relative to wild-type (WT) controls; P < 0.001] and showed marked elevation of plasma levels of CXCL1/KC, CCL2/MCP-1, IL-6, IL-10, IL-12 subunit p70, and soluble Fas ligand (P < 0.01), as well as systemic microvascular inflammation. It was not possible to assess later stages of atherosclerosis because of increased mortality in Fas−/− bone marrow recipients. Our data indicate that hematopoietic Fas deficiency does not affect early atherosclerotic lesion development in Ldlr−/− mice
A randomised, blinded, trial of clopidogrel versus aspirin in patients at risk of ischaemic events (CAPRIE). CAPRIE Steering Committee
Many clinical trials have evaluated the benefit of long-term use of antiplatelet drugs in reducing the risk of clinical thrombotic events. Aspirin and ticlopidine have been shown to be effective, but both have potentially serious adverse effects. Clopidogrel, a new thienopyridine derivative similar to ticlopidine, is an inhibitor of platelet aggregation induced by adenosine diphosphate. METHODS: CAPRIE was a randomised, blinded, international trial designed to assess the relative efficacy of clopidogrel (75 mg once daily) and aspirin (325 mg once daily) in reducing the risk of a composite outcome cluster of ischaemic stroke, myocardial infarction, or vascular death; their relative safety was also assessed. The population studied comprised subgroups of patients with atherosclerotic vascular disease manifested as either recent ischaemic stroke, recent myocardial infarction, or symptomatic peripheral arterial disease. Patients were followed for 1 to 3 years. FINDINGS: 19,185 patients, with more than 6300 in each of the clinical subgroups, were recruited over 3 years, with a mean follow-up of 1.91 years. There were 1960 first events included in the outcome cluster on which an intention-to-treat analysis showed that patients treated with clopidogrel had an annual 5.32% risk of ischaemic stroke, myocardial infarction, or vascular death compared with 5.83% with aspirin. These rates reflect a statistically significant (p = 0.043) relative-risk reduction of 8.7% in favour of clopidogrel (95% Cl 0.3-16.5). Corresponding on-treatment analysis yielded a relative-risk reduction of 9.4%. There were no major differences in terms of safety. Reported adverse experiences in the clopidogrel and aspirin groups judged to be severe included rash (0.26% vs 0.10%), diarrhoea (0.23% vs 0.11%), upper gastrointestinal discomfort (0.97% vs 1.22%), intracranial haemorrhage (0.33% vs 0.47%), and gastrointestinal haemorrhage (0.52% vs 0.72%), respectively. There were ten (0.10%) patients in the clopidogrel group with significant reductions in neutrophils (< 1.2 x 10(9)/L) and 16 (0.17%) in the aspirin group. INTERPRETATION: Long-term administration of clopidogrel to patients with atherosclerotic vascular disease is more effective than aspirin in reducing the combined risk of ischaemic stroke, myocardial infarction, or vascular death. The overall safety profile of clopidogrel is at least as good as that of medium-dose aspirin