水盾草 (Cabombacaroliniana)是原产南、北美洲的水生植物 ,近年来在野外调查中发现它在中国已经成为归化植物。通过华东、华南和华中地区的实地考察 ,调查点共 30 0多个 ,覆盖我国东南沿海及华中 10省 (市、区 ) 80多个县 (市 )。结果发现有水盾草分布的点 6 7个。目前水盾草在中国分布于浙江北部的杭嘉湖平原和宁绍平原、江苏南部的太湖流域及上海西部的淀山湖附近的河网地带。从地理纬度上看 ,自 2 9°33′7″N(建德梅城 )至 31°35′2″N(常熟昆承湖 ) ;主要的水域类型为一些水流缓慢、水位稳定的小河道和中小型湖泊。在水盾草所处的沉水植物群落中 ,共调查到大型沉水植物 8科 18属 2 1种 ,常见种为苦草 (Vallisnerianatans)、金鱼藻 (Ceratophyllumdemer sum)、黑藻 (Hydrillaverticillata)、菹草 (Potamogetoncrispus) ,这些也是浙北、苏南地区水域主要的水生植物。根据水盾草与各个种的种间相遇百分率来看 ,金鱼藻最高 ,为 5 1.33% ,其次为苦草、黑藻和菹草 ,分别为 4 5 .0 5 %、36 .5 6 %、35 .6 4 %。可见相对其他水生植物群落而言 ,由这些种所组成的水生植物群落更易为水盾草所侵入。从各个分布点水盾草所处状态来看 ,有些点的水盾草已成为群落的优势种 ,有的刚刚定居 ,还有的则仍处于零星漂

植物外侵种即当地原来没有而是由外地传入定植，并且对当地农林牧渔业生产，生态环境造成灾害的植物，称生态灾害植物。柳州属南亚热带季风气候区，很适宜植物生长、定植、繁衍，特别是植物外侵种有逐年成灾的趋头。据调查，植物外侵种在柳州市定植的目前有47种，其中13种成灾，9种严重成灾已经给农林牧渔业造成了较大的经济损失。

植物外侵种即当地原来没有而是由外地传入定植，并且对当地农林牧渔业生产，生态环境造成灾害的植物，称生态灾害植物。柳州属南亚热带季风气候区，很适宜植物生长、定植、繁衍，特别是植物外侵种有逐年成灾的趋头。据调查，植物外侵种在柳州市定植的目前有47种，其中13种成灾，9种严重成灾已经给农林牧渔业造成了较大的经济损失。

In recent years, changes have been detected in the climatic niches of several non-native species. In spite of this, and although Ecological Niche Models (ENMs) assume species show climatic niche conservatism, most studies still use ENM to assess the risks of invasion by alien species. In this study, we tested how niche expansion of the pond slider (Trachemys scripta) differs in invaded... [Show full abstract]

水盾草为原产南北美洲的沉水植物,目前已在我国归化.于2009年在江苏省内40个湿地进行了超过700个样点的调查.结果表明,水盾草目前已广泛分布于江苏省大部地区,定居纬度最北至33°41′N,并在大多数入侵群落成为优势种;与2003年相比,其入侵范围和入侵程度均有较大增长.在水盾草所处的植物群落,共调查到沉水植物17种和漂浮植物11种,其中,沉水植物轮叶黑藻、苦草和金鱼藻,漂浮植物槐叶萍、浮萍、满江红和荇菜与水盾草的种间相遇度均在50%以上,表明水盾草易于入侵有以上植物存在的河道.分析表明,水盾草在江苏省的入侵主要由人为扩散引起,然后顺流扩散.由于水盾草潜在人为扩散可能性依旧很大,且江苏省全域均适宜水盾草扩散,应加以高度重视和有效管理,否则水盾草极有可能在数年内扩散至全省.

水盾草为原产南北美洲的沉水植物,目前已在我国归化.于2009年在江苏省内40个湿地进行了超过700个样点的调查.结果表明,水盾草目前已广泛分布于江苏省大部地区,定居纬度最北至33°41′N,并在大多数入侵群落成为优势种;与2003年相比,其入侵范围和入侵程度均有较大增长.在水盾草所处的植物群落,共调查到沉水植物17种和漂浮植物11种,其中,沉水植物轮叶黑藻、苦草和金鱼藻,漂浮植物槐叶萍、浮萍、满江红和荇菜与水盾草的种间相遇度均在50%以上,表明水盾草易于入侵有以上植物存在的河道.分析表明,水盾草在江苏省的入侵主要由人为扩散引起,然后顺流扩散.由于水盾草潜在人为扩散可能性依旧很大,且江苏省全域均适宜水盾草扩散,应加以高度重视和有效管理,否则水盾草极有可能在数年内扩散至全省.

外来生物入侵与生境改变被认为是导致全球生物多样性下降的两大主因[1]。其中入侵植物通过营养竞争、植被结构改变、化感作用等,影响土著植物种群和群落,进而影响生态系统结构和功能。水生植物的入侵已成为影响我国淡水水体景观和生物多样性的重要因素[2—4]。水盾草

外来生物入侵与生境改变被认为是导致全球生物多样性下降的两大主因[1]。其中入侵植物通过营养竞争、植被结构改变、化感作用等,影响土著植物种群和群落,进而影响生态系统结构和功能。水生植物的入侵已成为影响我国淡水水体景观和生物多样性的重要因素[2—4]。水盾草

The area under the curve (AUC) of the receiver operating characteristic (ROC) has become a dominant tool in evaluating the accuracy of models predicting distributions of species. ROC has the advantage of being threshold-independent, and as such does not require decisions regarding thresholds of what constitutes a prediction of presence versus a prediction of absence. However, we show that, comparing two ROCs, using the AUC systematically undervalues models that do not provide predictions across the entire spectrum of proportional areas in the study area. Current ROC approaches in ecological niche modeling applications are also inappropriate because the two error components are weighted equally. We recommend a modification of ROC that remedies these problems, using partial-area ROC approaches to provide a firmer foundation for evaluation of predictions from ecological niche models. A worked example demonstrates that models that are evaluated favorably by traditional ROC AUCs are not necessarily the best when niche modeling considerations are incorporated into the design of the test.

Appendix for: Species-level forecasts of distributional potential and likely distributional shifts in the face of changing climates have become popular in the literature in the past 20 years. Many refinements have been made to the methodology over the years, and the result has been an approach that considers multiple sources of variation and how that variation translates into signal and uncertainty in the signal in the model outputs. Although numerous previous reviews and overviews of this field have pointed out a series of basic assumptions and caveats with the methodology, three aspects of the methodology have impacts that are nothing less than overwhelming, and that have not been treated previously in such assessments. Here, we assess (1) the effects of niche truncation on niche model transfers to future climate conditions, (2) the effects of model selection procedures in a future-transfer challenge for ecological niche models, and (3) the relative contributions of different factors (samples of point data, general circulation models, representative concentration pathways, alternative model parameterizations) to overall variance in model outcomes. Overall, the view is one of caution this paradigm has pitfalls and potholes that may bias and limit confidence in niche model outputs as regards the implications of climate change.

The assumption that climatic niche requirements of invasive species are conserved between their native and invaded ranges is key to predicting the risk of invasion. However, this assumption has been challenged recently by evidence of niche shifts in some species. Here, we report the first large-scale test of niche conservatism for 50 terrestrial plant invaders between Eurasia, North America, and Australia. We show that when analog climates are compared between regions, fewer than 15% of species have more than 10% of their invaded distribution outside their native climatic niche. These findings reveal that substantial niche shifts are rare in terrestrial plant invaders, providing support for an appropriate use of ecological niche models for the prediction of both biological invasions and responses to climate change.

Abstract Robust methods by which to generate virtual species are needed urgently in the emerging field of distributional ecology to evaluate performance of techniques for modeling ecological niches and species distributions and to generate new questions in biogeography. Virtual species provide the opportunity to test hypotheses and methods based on known and unbiased distributions. We present Niche Analyst (NicheA), a toolkit developed to generate virtual species following the Hutchinsonian approach of an n -multidimensional space occupied by the species. Ecological niche models are generated, analyzed, and visualized in an environmental space, and then projected to the geographic space in the form of continuous or binary species distribution models. NicheA is implemented in a stable and user-friendly Java platform. The software, online manual, and user support are freely available at .

冬去春来 ,“沉寂”已久的水盾草又蓄势待发 ,在江南的水域中开始了它新一轮的生长繁殖。水盾草（Ｃａｂｏｍｂａｃａｒｏｌｉｎｉａｎａ）别名绿菊花草 ,属于睡莲科。由于一年中大部分时间只见它的沉水叶 ,因此乍看上去极易误认为是金鱼藻科的金鱼藻（Ｃｅｒａｔｏｐｈｙｌ

冬去春来 ,“沉寂”已久的水盾草又蓄势待发 ,在江南的水域中开始了它新一轮的生长繁殖。水盾草（Ｃａｂｏｍｂａｃａｒｏｌｉｎｉａｎａ）别名绿菊花草 ,属于睡莲科。由于一年中大部分时间只见它的沉水叶 ,因此乍看上去极易误认为是金鱼藻科的金鱼藻（Ｃｅｒａｔｏｐｈｙｌ

Reptiles are the most species-rich group of terrestrial vertebrates, yet we lack a comprehensive understanding of their extinction risk. Only 45% of described reptile species have been assessed by IUCN to date (4648 of 10,400 species); of these, 20% (945 species) are threatened with extinction, and 19% (867 species) are Data Deficient. The goal of this special issue is to improve our understanding of reptile conservation needs and extinction risk by (i) investigating patterns and drivers of extinction risk and data deficiency at a global scale; (ii) identifying and addressing taxonomic and regional gaps in our understanding of extinction risk and data deficiency; and (iii) drawing upon detailed case studies to highlight conservation approaches to mitigate extinction. By doing so, the special issue will guide future conservation efforts toward the taxa and regions in greatest need of assessment, and toward risks requiring immediate mitigation. We conclude with potential avenues for future research, including the need to address regional knowledge gaps, conduct macroecological and retrospective analyses of extinction risk, and implement targeted monitoring of conservation intervention outcomes.

The utilization of species distribution model(s) (SDM) for approximating, explaining, and predicting changes in species’ geographic locations is increasingly promoted for proactive ecological management. Although frameworks for modeling non-invasive species distributions are relatively well developed, their counterparts for invasive species—which may not be at equilibrium within recipient environments and often exhibit rapid transformations—are lacking. Additionally, adaptive ecological management strategies address the causes and effects of biological invasions and other complex issues in social-ecological systems. We conducted a review of biological invasions, species distribution models, and adaptive practices in ecological management, and developed a framework for adaptive, niche-based, invasive species distribution model (iSDM) development and utilization. This iterative, 10-step framework promotes consistency and transparency in iSDM development, allows for changes in invasive drivers and filters, integrates mechanistic and correlative modeling techniques, balances the avoidance of type 1 and type 2 errors in predictions, encourages the linking of monitoring and management actions, and facilitates incremental improvements in models and management across space, time, and institutional boundaries. These improvements are useful for advancing coordinated invasive species modeling, management and monitoring from local scales to the regional, continental and global scales at which biological invasions occur and harm native ecosystems and economies, as well as for anticipating and responding to biological invasions under continuing global change.

睡莲科水盾草属，迄今在我国尚未见报道，作者先后在青浦和吴县等地调查植物时，采集到水盾草属的竹节水松（鱼草）。这一发现不仅丰富了我国的植物种类、区系成份和资源植物，而且对《中国植物志》的修订再版和植物资源的开发利用提供了新信息

睡莲科水盾草属，迄今在我国尚未见报道，作者先后在青浦和吴县等地调查植物时，采集到水盾草属的竹节水松（鱼草）。这一发现不仅丰富了我国的植物种类、区系成份和资源植物，而且对《中国植物志》的修订再版和植物资源的开发利用提供了新信息

本文从外来种本身的生物学特性、外来种与新栖息地土著种之间的相互作用、群落生物多样性对入 侵种的抵抗能力、新栖息地生态环境变化对入侵种的影响等方面综述了近年来有关生物入侵机制的研究进展,并探讨了研究方法的发展和亟待解决的问题.大量的研 究表明生物入侵机制是极为多样的,可能没有一般的、通用的机制.阐明生物入侵的机制,对推动生态学理论的发展和控制有害外来种有重要意义.

本文从外来种本身的生物学特性、外来种与新栖息地土著种之间的相互作用、群落生物多样性对入 侵种的抵抗能力、新栖息地生态环境变化对入侵种的影响等方面综述了近年来有关生物入侵机制的研究进展,并探讨了研究方法的发展和亟待解决的问题.大量的研 究表明生物入侵机制是极为多样的,可能没有一般的、通用的机制.阐明生物入侵的机制,对推动生态学理论的发展和控制有害外来种有重要意义.

[目的]生态位模型在生物地理学、入侵生物学和保护生物学中具有广泛的应用,被越来越多地用于预测物种潜在分布和现实分布的研究中.本文以美国白蛾为例介绍pROC方案在生态位模型评价中的应用及其注意事项,以期对物种潜在分布预测进行合理的评价,促进生态位模型在我国的合理运用和发展.[方法]介绍ROC曲线和AUC值基本原理,总结其在生态位模型评价中的应用,从物种存在分布点和不存在分布点的可信度出发,分析AUC值用于模型评价的优点和不足,最后介绍局部受试者工作特征曲线的线下面积方案(pROC方案)来弥补传统AUC值的不足.[结果]AUC值虽独立于阈值,但因其综合灵敏度和特异度,而屏蔽这2个指标各自的特征,不能分别评估预测结果的灵敏度和特异度,同时对遗漏率和记账错率不能进行权衡,会误导使用者对模型的评价.与AUC值相比,ROC曲线的形状更具有价值,蕴含丰富的模型评价信息.[结论]模型评价需要将灵敏度和特异度区别对待,ROC曲线形状比AUC值在生态位模型评价中更为重要,pROC方案相对于传统AUC值具有优势,但容易对过度模拟做出不当判断.模型评价与作者研究目的密切相关:当以预测物种潜在分布为目的时(如入侵物种潜在分布、气候变化对物种分布的影响和谱系生物地理学),模型评价应当给予灵敏度(或者遗漏率)更多的权重;当以预测物种现实分布为目的时(如保护区界定和濒危物种引入),模型评价应当给予灵敏度和特异度同等的权重.

[目的]生态位模型在生物地理学、入侵生物学和保护生物学中具有广泛的应用,被越来越多地用于预测物种潜在分布和现实分布的研究中.本文以美国白蛾为例介绍pROC方案在生态位模型评价中的应用及其注意事项,以期对物种潜在分布预测进行合理的评价,促进生态位模型在我国的合理运用和发展.[方法]介绍ROC曲线和AUC值基本原理,总结其在生态位模型评价中的应用,从物种存在分布点和不存在分布点的可信度出发,分析AUC值用于模型评价的优点和不足,最后介绍局部受试者工作特征曲线的线下面积方案(pROC方案)来弥补传统AUC值的不足.[结果]AUC值虽独立于阈值,但因其综合灵敏度和特异度,而屏蔽这2个指标各自的特征,不能分别评估预测结果的灵敏度和特异度,同时对遗漏率和记账错率不能进行权衡,会误导使用者对模型的评价.与AUC值相比,ROC曲线的形状更具有价值,蕴含丰富的模型评价信息.[结论]模型评价需要将灵敏度和特异度区别对待,ROC曲线形状比AUC值在生态位模型评价中更为重要,pROC方案相对于传统AUC值具有优势,但容易对过度模拟做出不当判断.模型评价与作者研究目的密切相关:当以预测物种潜在分布为目的时(如入侵物种潜在分布、气候变化对物种分布的影响和谱系生物地理学),模型评价应当给予灵敏度(或者遗漏率)更多的权重;当以预测物种现实分布为目的时(如保护区界定和濒危物种引入),模型评价应当给予灵敏度和特异度同等的权重.

Abstract Studies of realized niche shift and model trans- ferability in alien species usually ignore the potential effects of source populations and different invaded-range environ- ments on niche lability. We incorporate our detailed knowledge of the native-range source populations and glo- bal introduction history of brown marmorated stink bug (Halyomorpha halys) to examine intraspecific variation in realized niche expansion and unfilling, and to investigate how niche modelling approaches are affected by that vari- ation. Realized niche dynamics of H. halys were analyzed

生态位模型利用物种分布点所关联的环境变量去推算物种的生态需求,模拟物种的分布.在模拟入侵物种分布 时,经典生态位模型包括模型构建于物种本土分布地,然后将其转移并投射至另一地理区域,来模拟入侵物种的潜在分布.然而在模型运用时,出现了模型的转移能 力较低、模拟的结果与物种的实际分布不相符的情况,由此得出了生态位漂移等不恰当的结论.提高生态位模型的转移能力,可以准确地模拟入侵物种的潜在分布, 为入侵种的风险评估提供参考.作者以入侵种茶翅蝽(Halyomorpha halys)和互花米草(Spartina alterniflora)为例,从模型的构建材料(即物种分布点和环境变量)入手,全面阐述提高模型转移能力的策略.在构建模型之前,需要充分了解入侵 物种的生物学特性、种群平衡状态、本土地理分布范围及物种的生物历史地理等方面的知识.在模型构建环节上,物种分布点不仅要充分覆盖物种的地理分布和生态 空间的范围,同时要降低物种采样点偏差;环境变量的选择要充分考虑其对物种分布的限制作用、各环境变量之间的空间相关性,以及不同地理种群间生态空间是否 一致,同时要降低环境变量的空间维度;模型构建区域要真实地反映物种的地理分布范围,并考虑种群的平衡状态.作者认为,在生态位保守的前提下,如果模型是 构建在一个合理方案的基础上,生态位模型的转移能力是可以保证的,在以模型转移能力较低的现象来阐述生态位分化时需要引起注意.

生态位模型利用物种分布点所关联的环境变量去推算物种的生态需求,模拟物种的分布.在模拟入侵物种分布 时,经典生态位模型包括模型构建于物种本土分布地,然后将其转移并投射至另一地理区域,来模拟入侵物种的潜在分布.然而在模型运用时,出现了模型的转移能 力较低、模拟的结果与物种的实际分布不相符的情况,由此得出了生态位漂移等不恰当的结论.提高生态位模型的转移能力,可以准确地模拟入侵物种的潜在分布, 为入侵种的风险评估提供参考.作者以入侵种茶翅蝽(Halyomorpha halys)和互花米草(Spartina alterniflora)为例,从模型的构建材料(即物种分布点和环境变量)入手,全面阐述提高模型转移能力的策略.在构建模型之前,需要充分了解入侵 物种的生物学特性、种群平衡状态、本土地理分布范围及物种的生物历史地理等方面的知识.在模型构建环节上,物种分布点不仅要充分覆盖物种的地理分布和生态 空间的范围,同时要降低物种采样点偏差;环境变量的选择要充分考虑其对物种分布的限制作用、各环境变量之间的空间相关性,以及不同地理种群间生态空间是否 一致,同时要降低环境变量的空间维度;模型构建区域要真实地反映物种的地理分布范围,并考虑种群的平衡状态.作者认为,在生态位保守的前提下,如果模型是 构建在一个合理方案的基础上,生态位模型的转移能力是可以保证的,在以模型转移能力较低的现象来阐述生态位分化时需要引起注意.

Summary Species distribution models (SDMs) have become a standard tool in ecology and applied conservation biology. Modelling rare and threatened species is particularly important for conservation purposes. However, modelling rare species is difficult because the combination of few occurrences and many predictor variables easily leads to model overfitting. A new strategy using ensembles of small models was recently developed in an attempt to overcome this limitation of rare species modelling and has been tested successfully for only a single species so far. Here, we aim to test the approach more comprehensively on a large number of species including a transferability assessment. For each species, numerous small (here bivariate) models were calibrated, evaluated and averaged to an ensemble weighted by AUC scores. These nsembles of small models (ESMs) were compared to standard SDMs using three commonly used modelling techniques (GLM, GBM and Maxent) and their ensemble prediction. We tested 107 rare and under-sampled plant species of conservation concern in Switzerland. We show that ESMs performed significantly better than standard SDMs. The rarer the species, the more pronounced the effects were. ESMs were also superior to standard SDMs and their ensemble when they were evaluated using a transferability assessment. By averaging simple small models to an ensemble, ESMs avoid overfitting without losing explanatory power through reducing the number of predictor variables. They further improve the reliability of species distribution models, especially for rare species, and thus help to overcome limitations of modelling rare species.

SDMtoolbox 2.0 is a software package for spatial studies of ecology, evolution, and genetics. The release of SDMtoolbox 2.0 allows researchers to use the most current ArcGIS software and MaxEnt software, and reduces the amount of time that would be spent developing common solutions. The central aim of this software is to automate complicated and repetitive spatial analyses in an intuitive graphical user interface. One core tenant facilitates careful parameterization of species distribution models (SDMs) to maximize each model’s discriminatory ability and minimize overfitting. This includes carefully processing of occurrence data, environmental data, and model parameterization. This program directly interfaces with MaxEnt, one of the most powerful and widely used species distribution modeling software programs, although SDMtoolbox 2.0 is not limited to species distribution modeling or restricted to modeling in MaxEnt. Many of the SDM pre- and post-processing tools have ‘universal’ analogs for use with any modeling software. The current version contains a total of 79 scripts that harness the power of ArcGIS for macroecology, landscape genetics, and evolutionary studies. For example, these tools allow for biodiversity quantification (such as species richness or corrected weighted endemism), generation of least-cost paths and corridors among shared haplotypes, assessment of the significance of spatial randomizations, and enforcement of dispersal limitations of SDMs projected into future climates—to only name a few functions contained in SDMtoolbox 2.0. Lastly, dozens of generalized tools exists for batch processing and conversion of GIS data types or formats, which are broadly useful to any ArcMap user.

This paper reports a newly naturalized aquatic genus Cabomba Aublet. (Cabombaceae) in China.

This paper reports a newly naturalized aquatic genus Cabomba Aublet. (Cabombaceae) in China.

The allele frequency spectrum has attracted considerable interest for the simultaneous inference of the demographic and adaptive history of populations. In a recent study, Evans et02al. (2007) developed a forward diffusion equation describing the allele frequency spectrum, when the population is subject to size changes, selection and mutation. From the diffusion equation, the authors derived a system of ordinary differential equations (ODEs) for the moments in a Wright–Fisher diffusion with varying population size and constant selection. Here, we present an explicit solution for this system of ODEs with variable population size, but without selection, and apply this result to derive the expected spectrum of a sample for time-varying population size. We use this forward-in-time-solution of the allele frequency spectrum to obtain the backward-in-time-solution previously derived via coalescent theory by Griffiths and Tavaré (1998). Finally, we discuss the applicability of the theoretical results to the analysis of nucleotide polymorphism data.

水盾草 (Cabombacaroliniana)是原产南、北美洲的水生植物 ,近年来在野外调查中发现它在中国已经成为归化植物。通过华东、华南和华中地区的实地考察 ,调查点共 30 0多个 ,覆盖我国东南沿海及华中 10省 (市、区 ) 80多个县 (市 )。结果发现有水盾草分布的点 6 7个。目前水盾草在中国分布于浙江北部的杭嘉湖平原和宁绍平原、江苏南部的太湖流域及上海西部的淀山湖附近的河网地带。从地理纬度上看 ,自 2 9°33′7″N(建德梅城 )至 31°35′2″N(常熟昆承湖 ) ;主要的水域类型为一些水流缓慢、水位稳定的小河道和中小型湖泊。在水盾草所处的沉水植物群落中 ,共调查到大型沉水植物 8科 18属 2 1种 ,常见种为苦草 (Vallisnerianatans)、金鱼藻 (Ceratophyllumdemer sum)、黑藻 (Hydrillaverticillata)、菹草 (Potamogetoncrispus) ,这些也是浙北、苏南地区水域主要的水生植物。根据水盾草与各个种的种间相遇百分率来看 ,金鱼藻最高 ,为 5 1.33% ,其次为苦草、黑藻和菹草 ,分别为 4 5 .0 5 %、36 .5 6 %、35 .6 4 %。可见相对其他水生植物群落而言 ,由这些种所组成的水生植物群落更易为水盾草所侵入。从各个分布点水盾草所处状态来看 ,有些点的水盾草已成为群落的优势种 ,有的刚刚定居 ,还有的则仍处于零星漂