关键词： 哺乳动物化石   内蒙古宁城   河北省   地穴   树栖   中国地质科学院   地球   中国北方地区  

摘要： 据2015年2月13日《参考消息》援引报道，美国芝加哥大学和中国地质科学院地质研究所研究人员在中国北方地区发现两件柱齿兽类的原始哺乳动物化石。其中一种被命名为攀援灵巧柱齿兽的化石于2011年发现于内蒙古宁城，生活在距今1．65亿年前，是已知最早的树栖型哺乳动物，有特化的牙齿可食树汁树液。另一种被命名为短指挖掘柱齿兽的化石于2012年发现于河北省青龙县，生活在距今1．6亿年前，是已知最早的地穴型哺乳动物，牙齿可食昆虫。

关键词： common garden   community assembly theory   community evolution   community networks   community phenotype   community-genetic correlations   ecological genetics and ecogenomics   interacting foundation species hypothesis   physical proximity hypothesis   Populus  

摘要： Community genetics studies frequently focus on individual communities associated with individual plant genotypes, but little is known about the genetically based relationships among taxonomically and spatially disparate communities. We integrate studies of a wide range of communities living on the same plant genotypes to understand how the ecological and evolutionary dynamics of one community may be constrained or modulated by its underlying genetic connections to another community. We use pre-existing data sets collected from Populus angustifolia (narrowleaf cottonwood) growing in a common garden to test the hypothesis that the composition of pairs of distinct communities (e.g. endophytes, pathogens, lichens, arthropods, soil microbes) covary across tree genotypes, such that individual plant genotypes that support a unique composition of one community are more likely to support a unique composition of another community. We then evaluate the hypotheses that physical proximity, taxonomic similarity, time between sampling (time attenuation), and interacting foundation species within communities explain the strength of correlations. Three main results emerged. First, Mantel tests between communities revealed moderate to strong (=0.25-0.85) community-genetic correlations in almost half of the comparisons;correlations among phyllosphere endophyte, pathogen and arthropod communities were the most robust. Secondly, physical proximity determined the strength of community-genetic correlations, supporting a physical proximity hypothesis. Thirdly, consistent with the interacting foundation species hypothesis, the most abundant species drove many of the stronger correlations. Other hypotheses were not ***. The field of community genetics demonstrates that the structure of communities varies among plant genotypes;our results add to this field by showing that disparate communities covary among plant genotypes. Eco-evolutionary dynamics between plants and their ass

关键词： Livestock   Facilitation   Herbivory   Nurse plants   Spatial association  

摘要： Successful persistence of dry forests depends on tree regeneration, which depends on a balance of complex biotic interactions. In particular, the relative importance and interactive effects of shrubs and herbivores on tree regeneration are unclear. In a manipulative study, we investigated if thornless shrubs have a direct net effect, an indirect positive effect mediated by livestock, and/or an indirect negative effect mediated by small vertebrates on tree regeneration of two key species of Chaco forest (Argentina). In a spatial association study, we also explored the existence of net positive interactions from thorny and thornless shrubs. The number of Schinopsis lorentzii seedlings was highest under artificial shade with native herbivores and livestock excluded. Even excluding livestock, no seedlings were found with natural conditions (native herbivores present with natural shade or direct sunlight) at the end of the experiment. Surprisingly, seedling recruitment was not enhanced under thornless shrubs, because there was a complementary positive effect of shade and interference. Moreover, thornless shrubs had neither positive nor negative effects on regeneration of S. lorentzii. Regeneration of Aspidosperma quebracho-blanco was minimal in all treatments. In agreement with the experiment, spatial distributions of saplings of both tree species were independent of thornless shrubs, but positively associated with thorny shrubs. Our results suggest that in general thornless shrubs may have a negligible effect and thorny shrubs a net positive effect on tree regeneration in dry forests. These findings provide a conceptual framework for testing the impact of biotic interactions on seedling recruitment in other dry forests.

关键词： pyroelectric array sensor   segmentation   wavelets   hidden Markov tree model   expectation-maximization algorithm   scale invariant feature transform   speeded up robust features  

摘要： Linear pyroelectric array sensors have enabled useful classifications of objects such as humans and animals to be performed with relatively low-cost hardware in border and perimeter security applications. Ongoing research has sought to improve the performance of these sensors through signal processing algorithms. In the research presented here, we introduce the use of hidden Markov tree (HMT) models for object recognition in images generated by linear pyroelectric sensors. HMTs are trained to statistically model the wavelet features of individual objects through an expectation-maximization learning process. Human versus animal classification for a test object is made by evaluating its wavelet features against the trained HMTs using the maximum-likelihood criterion. The classification performance of this approach is compared to two other techniques;a texture, shape, and spectral component features (TSSF) based classifier and a speeded-up robust feature (SURF) classifier. The evaluation indicates that among the three techniques, the wavelet-based HMT model works well, is robust, and has improved classification performance compared to a SURF-based algorithm in equivalent computation time. When compared to the TSSF-based classifier, the HMT model has a slightly degraded performance but almost an order of magnitude improvement in computation time enabling real-time implementation. (C) 2015 Society of Photo-Optical Instrumentation Engineers (SPIE)

关键词： 丙型肝炎病毒   树鼩   动物模型  

摘要： 丙型肝炎病毒(HCV)感染是全球关注的公共健康问题之一。只有建立稳定可靠的HCV感染模型,才能更好地研究HCV感染慢性化和致癌的机制,从而推动丙型肝炎疫苗的研制和抗丙型肝炎药物的筛选。HCV宿主范围特别狭窄,只有人和黑猩猩对其易患。目前有一些体内和体外的实验结果初步显示,树鼩是目前继黑猩猩之后唯一能感染HCV的动物。该文对HCV感染树鼩动物模型的研究进展予以行综述。

关键词： Frogs   Earthworms   Worms   Ureter   Host specificity   Experimental infection   Ecological life histories  

摘要： Given their ubiquitous nature, it is surprising that more oligochaete annelid worms (Annelida: Clitellata) have not adopted an endoparasitic lifestyle. Exceptions, however, are the understudied members of the genus Dero (Allodero) that parasitize the ureters of tree frogs and toads. This study experimentally explores the life cycle and host specificity of Allodero hylae, the worm's use of chemical cues in host searching, and its seasonal prevalence and abundance over a year-long collection period on the Florida Southern College campus. A total of 2,005 A. hylae was collected from the ureter, urinary bladder, or expressed urine of wild Osteopilus septentrionalis;a significant positive correlation was found between host snout-vent length and parasite intensity for female but not male hosts. Monthly prevalence of A. hylae reached a peak of 58% in April, but never dropped below 20% in any month;mean abundance peaked March-May, whereas few worms were recovered in December and January. Confirming a parasitic lifestyle, wild-collected hosts with intense infections, typically >40 worms, showed obvious dilatation of the ureter wall, and some young-of-the-year O. septentrionalis exposed to A. hylae in the laboratory were killed by the apparent rupture of the host's ureter. The worm has a direct life cycle: worms expelled in the host's urine are capable of locating and re-infecting other hosts within aquatic microhabitats such as bromeliad tanks, and worms can survive for weeks in a free-living environment, even undergoing a morphological change. Further, chemotaxis assays found a positive response to a tree frog attractant for worms recently removed from hosts. Overall, this study provides the first multifaceted investigation on the life history and ecology of any Allodero spp., which offers new insights into an understudied endoparasitic oligochaete.

关键词： Extinction   Fire intensity   Fire management   Population viability analysis   Savanna   Threatened species   Simulation experiment  

摘要： Patch-mosaic burning is a widely accepted practical approach to managing biodiversity, whereby spatial and temporal diversity of fire is manipulated to benefit biotic diversity. We use simulation experiments based on stochastic population viability analysis to evaluate the implications of contrasting patch-mosaic burning scenarios for the population dynamics and risk of decline of four species of small mammals in northern Australia. Our results, based on models developed from detailed mark-recapture data, suggest that fire frequency has more influence on small-mammal persistence than fire extent. Risk of extinction increased for all four species when fire frequency exceeded once every five years. Under current ambient fire regimes most Australia tropical savannas burn more frequently and therefore seem to have unfavourable consequences for this faunal group and risk precipitating severe future declines. Crown Copyright (C) 2015 Published by Elsevier Ltd. All rights reserved.

关键词： Light trapping   light color   biting midges   vector control   light sources  

摘要： The role of the light-emitting diode (LED) modified light traps in the attraction of biting midges was evaluated in Northeastern Maranhao, Brazil. The modified traps held a 5 mm high-brightness LED bulb, one in the green (520 nm) and other in the blue (470 nm) region of the visible spectrum. The incandescent bulb was used as control. From a total of 2,764 specimens, the most frequent species were Culicoides lutzi Costa Lima (58.54%), C. paucienfuscatus Barbosa (27.30%), C. duartei Tavares and Luna Dias (4.74%) and C. insignis Lutz (4.63%). The green light source accounted for 53.87% of the sampled individuals, followed by incandescent (34.95%) and blue lights (11.18%), but these differences were not statistically significant. The differences found among the species' responses demonstrate that variances in species-specific LED attractiveness exist and the results must be individually evaluated. Even without statistical differences, it is suggested to use LEDs as an alternative for the Culicoides collections because of important advantages compared to incandescent lamps.

关键词： Mesquite   Wild ass   Invasion   India   Grasslands   Biodiversity  

摘要： Wild Ass Wildlife Sanctuary is one of the largest wildlife sanctuaries in India represents 'Indian wild ass' (Equus hemionus khur), an endangered desert mammal of the world. The present study has found desert mammals are supporting rapid invasion of Mesquite (Prosopis juliflora). Multi-temporal satellite images of 1977-2011 have been used for spatial quantification of Mesquite. The annual expansion rate of Mesquite cover has been estimated between 1.66 and 6.87 during the studied phases indicates significant threat to indigenous biodiversity.

关键词： African elephant   death   encephalomyocarditis   Loxodonta africana   virus   zoo  

摘要： A fatal case of encephalomyocarditis virus (EMCV) involving an African elephant (Loxodonta africana) occurred in November 2013 at the Reserve Africaine de Sigean, France. An adult female was found dead without any preliminary symptoms. Gross pathologic changes consisted of petechiae and hemorrhages on mucosae and internal organs, abundant transudate in the abdominal and pericardial cavities, and myocarditis. Histopathologic examination showed extensive degeneration and necrosis of ventricular cardiomyocytes with concurrent lymphoplasmocytic and eosinophilic infiltrate. An EMCV was isolated from several organs and considered the causative agent of the myocarditis. The same strain of virus was also isolated in rodents captured on zoo premises and considered to be the reservoir of the virus. To the authors' knowledge, this is the first EMCV case in a captive African elephant in Europe.