气候变化背景下入侵植物曼陀罗在西藏的潜在风险区预测

生物安全与外来物种入侵是国门生物安全的重大生态学问题,生物入侵造成了巨大的经济损失与生物多样性快速丧失,还影响着人类的身体健康。西藏是我国重要的生态安全屏障,生态类型复杂且丰富多样,明确西藏区域尺度上外来入侵植物的潜在分布格局及其对气候变化的响应对入侵植物的预防和控制具有重要意义。为了探究入侵植物曼陀罗(Datura stramonium L.)对西藏生态安全的影响风险,基于野外实地调查数据,采用最大熵(Maxent) 模型,应用R语言和SPSS软件对模型参数和数据进行优化筛选,探讨影响其地理分布的主要环境因子,并模拟预测了当代及2种气候变化情景(RCP 45、RCP 85)下2050年和2070年, 其在西藏的潜在入侵风险区分布情况。结果表明:下层土壤酸碱度、年平均气温、最暖月最高温度与土壤有效含水量是影响曼陀罗分布的主导环境因子,海拔和人类活动影响强度也有重要作用;朗县、加查县、乃东区、城关区、八宿县、贡嘎县、巴宜区、波密县、察隅县、芒康县等地为入侵高风险地区;两种气候背景下曼陀罗的各级风险区面积和总风险区面积均呈持续增加的变化趋势,且在最高碳排放情景(RCP 85情景)下响应更为敏感;主要沿着低海拔河谷区域东南向西北方向入侵扩散的趋势,分布中心由当前的墨脱县域向工布江达县域转移。综合来说,曼陀罗在西藏分布受土壤环境、温度和降水影响较大,气候变化和人类活动影响强度将使其向西藏西部、北部扩散。研究结果可为西藏地区综合防控曼陀罗的入侵危害与动态监测提供生态学基础理论依据。     

Development and validation of a method for purification of mallein for the diagnosis of glanders in equines

ABSTRACT: BACKGROUND: The allergic test of mallein is one of the most frequently used tests, together with the Complement Fixation Test (CFT), for the diagnosis of glanders in endemic areas. Mallein, a purified protein derivative (PPD), is produced similarly to PPD tuberculin and the end product is a primarily proteic antigen, which is only poorly purified. The immuno-allergic activity of mallein is believed to be due to a high molecular weight group of proteins present in the antigen. To improve the quality of the antigen, in terms of sensitivity and specificity, a new method of mallein production was developed, in which purification was accomplished by ultrafiltration in a Tangential Flow Filtration system (TFF). RESULTS: The TFF methodology efficiently separated the high and low molecular weight protein groups of mallein. The five TFF-purified malleins, produced from Burkholderia mallei strains isolated from clinical cases of glanders in Brazil, proved to be more potent than standard mallein in the induction of an allergic reaction in sensitized animals. Regarding specificity, two of the purified malleins were equivalent to the standard and three were less specific. CONCLUSION: Some of the TFF-purified malleins showed considerable potential to be used as an auxiliary test in the diagnosis of glanders.     

Vertical transmission in feather mites: insights into its adaptive value

1. The consequences of symbiont transmission strategies are better understood than their adaptive causes. 2. Feather mites are permanent ectosymbionts of birds assumed to be transmitted mainly vertically from parents to offspring. The transmission of Proctophyllodes doleophyes Gaud (Astigmata, Proctophyllodidae) was studied in two European populations of pied flycatchers, Ficedula hypoleuca Pallas (Passeriformes, Muscicapidae). 3. The vertical transmission of this mite species is demonstrated here with an acaricide experiment. This study also compared (for two distant populations during 4 years) patterns in reductions in mite intensity in adult birds, from egg incubation to chick‐rearing periods, with the predictions of three hypotheses on how host survival prospects and mite intraspecific competition might drive feather mites' transmission strategy. 4. The results are in agreement with previous studies and show that feather mites transmit massively from parents to chicks. 5. The magnitude of the transmission was closer to that predicted by the hypothesis based on intraspecific competition, while a bet‐hedging strategy is also partially supported.     

Uncertainty in ensemble forecasting of species distribution

Species distribution modelling has been widely applied in order to assess the potential impacts of climate change on biodiversity. Many methodological decisions, taken during the modelling process and forecasts, may, however, lead to a large variability in the assessment of future impacts. Using measures of species range change and turnover, the potential impacts of climate change on French stream fish species and assemblages were evaluated. Our main focus was to quantify the uncertainty in the projections of these impacts arising from four sources of uncertainty: initial datasets (Data), statistical methods [species distribution models (SDM)], general circulation models (GCM), and gas emission scenarios (GES). Several modalities of the aforementioned uncertainty sources were combined in an ensemble forecasting framework resulting in 8400 different projections. The variance explained by each source was then extracted from this whole ensemble of projections. Overall, SDM contributed to the largest variation in projections, followed by GCM, whose contribution increased over time equalling almost the proportion of variance explained by SDM in 2080. Data and GES had little influence on the variability in projections. Future projections of range change were more consistent for species with a large geographical extent (i.e., distribution along latitudinal or stream gradients) or with restricted environmental requirements (i.e., small thermal or elevation ranges). Variability in projections of turnover was spatially structured at the scale of France, indicating that certain particular geographical areas should be considered with care when projecting the potential impacts of climate change. The results of this study, therefore, emphasized that particular attention should be paid to the use of predictions ensembles resulting from the application of several statistical methods and climate models. Moreover, forecasted impacts of climate change should always be provided with an assessment of their uncertainty, so that management and conservation decisions can be taken in the full knowledge of their reliability.     

Eight polymorphic microsatellite markers in the Andalusian belladonna (Atropa baetica, Solanaceae)

We report on the isolation and characterization of eight microsatellite markers from enriched libraries for the critically endangered Atropa baetica. These are the first microsatellite loci reported for Atropa species. The total number of alleles found was 18, the expected heterozygosity ranged from 0.198 to 0.505. These markers will be useful to establish the real census of individuals and the genetic diversity both within and among the different populations of A. baetica.