土著昆虫素毒蛾对入侵植物互花米草地理种群的选择性

外来植物入侵后会改变其对入侵地植食性昆虫的防御能力以应对入侵地生物环境的变化,因此,对土著昆虫防御能力变化的研究将有助于解释外来植物成功入侵的机制。互花米草(Spartina alterniflora)是广泛入侵中国东部沿海地区的外来植物,研究其入侵后对本地植食性昆虫的响应,可从一个侧面部分地回答其成功入侵的生态机制。利用Y型嗅觉仪,结合室内取食实验,我们比较了中国的土著昆虫素毒蛾(Laelia coenosa)对互花米草3个原产地种群和5个入侵地种群的选择偏好,这些种群分别来自美国的德克萨斯(Texas Point)、卡纳维拉尔国家海岸(Canaveral National Seashore)、佛罗里达大西洋大学(Florida Atlantic University),以及中国的唐海、天津、盐城、崇明、珠海。结果表明,虽然素毒蛾幼虫对互花米草不同地理种群叶片气味没有显著的选择偏好,但对原产地种群的取食相对选择系数显著高于入侵地种群,说明互花米草入侵地种群对素毒蛾的抵抗能力相对较强。这从某种层面上可以推测互花米草入侵中国东部沿海地区以后,其对植食性昆虫取食的防御能力有所增强,而这种能力将在一定程度上减少素毒蛾等入侵地植食动物对它的攻击。     

丛枝菌根真菌（AMF）对外来植物入侵反馈机制的研究进展

丛枝菌根真菌（AMF）在植物群落竞争演替、物种多样性的形成及群落空间分布格局、植物群落对全球变化的响应中均起着重要的调节作用;同样也能影响外来植物与本地植物的互作,影响外来植物入侵过程中植物群落演替进程,甚至决定入侵的成败。因此,AMF与外来植物共生及其对外来植物入侵的反馈已成为国际上外来植物入侵机制研究的一个热点。本文基于外来植物的入侵过程,从AMF对外来植物生长、外来植物与本地植物竞争关系的影响,以及外来植物入侵对AMF的影响及AMF对入侵的反馈3个方面综述了AMF对外来植物入侵的反馈机制。外来植物可以通过多种途径改变土著AMF的群落结构和功能,而土著AMF也能直接或间接地改变甚至逆转外来植物与入侵地植物的互作关系。未来的研究不仅需要考虑AMF与外来植物共生的菌根特性和对竞争关系的影响,还需要通过大尺度条件下的野外试验及室内补充试验深入探究影响AMF在外来植物与本地植物竞争演替中的作用的生物和非生物因子,以全面解释AMF影响外来植物入侵的反馈机制。     

丛枝菌根真菌（AMF）对外来植物入侵反馈机制的研究进展

丛枝菌根真菌（AMF）在植物群落竞争演替、物种多样性的形成及群落空间分布格局、植物群落对全球变化的响应中均起着重要的调节作用;同样也能影响外来植物与本地植物的互作,影响外来植物入侵过程中植物群落演替进程,甚至决定入侵的成败。因此,AMF与外来植物共生及其对外来植物入侵的反馈已成为国际上外来植物入侵机制研究的一个热点。本文基于外来植物的入侵过程,从AMF对外来植物生长、外来植物与本地植物竞争关系的影响,以及外来植物入侵对AMF的影响及AMF对入侵的反馈3个方面综述了AMF对外来植物入侵的反馈机制。外来植物可以通过多种途径改变土著AMF的群落结构和功能,而土著AMF也能直接或间接地改变甚至逆转外来植物与入侵地植物的互作关系。未来的研究不仅需要考虑AMF与外来植物共生的菌根特性和对竞争关系的影响,还需要通过大尺度条件下的野外试验及室内补充试验深入探究影响AMF在外来植物与本地植物竞争演替中的作用的生物和非生物因子,以全面解释AMF影响外来植物入侵的反馈机制。     

南宁老虎岭林区多种外来植物入侵程度与影响因子模型解释

了解森林环境中多种外来植物对多种环境因子的互作效应,可以更有针对性地应对外来入侵威胁。在南宁老虎岭林区分6个区进行样方调查,以样方所有外来植物的相对百分比作为外来植物入侵程度,利用以分区为随机截距的混合效应模型和一般线性模型来分析有关因素对入侵的影响,用R-effects包的互作效应图形化和数据提取来解释互作效应的复杂变化。多因素混合效应模型分析表明,路边对入侵的主效应为正且极显著(P=0.000),林冠郁蔽度和优势最大株高对入侵的主效应为负(P=0.000),土著物种丰富度对入侵的主效应不显著,但土著物种丰富度与路边的互作对入侵的效应极显著(P=0.007);路边的土著物种丰富度明显提升入侵抵抗性,但林内的土著物种丰富度只能微弱增加入侵抵抗性;林冠郁蔽度和优势最大株高的互作对入侵的效应极显著(P=0.004),但两个因素对入侵的限制作用非可加。一般线性模型分析表明,林龄和抚育时间对外来植物入侵的影响趋势不明显;未发现引进树种造林与乡土树种造林的林下外来植物入侵程度有差异;相对于林道的样方位置高低影响入侵程度,林道下方的样方较易被入侵。在监测或防控林业外来植物时,重点应放在低于林道的森林。     

外来杂草入侵的化学机制

由外来杂草入侵引发的严重生态和经济问题已倍受关注,外来杂草在新生境成功入侵,除了具备一些基本的生物生态学特征外,还应具备一些特有的入侵机制,阐明外来杂草的各种入侵机制可以为入侵杂草的预测和控制提供科学依据。外来杂草只有在新生境中与原产地生物种间的相互作用中取得优势,才能定植并扩增种群而成功入侵．在这些外来杂草和原产地生物种间的相互作用关系中,化学关系是不可忽视的方面．目前研究已经证实：植物的化感作用在外来杂草成功入侵中发挥着重要的作用．事实上,植物也可以通过合成和释放特定的化学物质防御或抑制新生境的动物、植物和微生物．外来杂草入侵的化学机制涉及到植物化学生态学的各个方面。因此,外来杂草的化学生态学特征应作为入侵种预测的重要指标之一,外来杂草入侵的化学机制应是今后重要的研究方向。     

重要外来入侵植物随南水北调工程传入京津冀受水区的风险评估

【目的】外来物种在入侵地的扩张蔓延是其造成危害的关键。南水北调工程可为已入侵外来物种的进一步扩张蔓延提供通道和驱动力。风险评估可为预防入侵植物通过该途径的扩散蔓延提供依据。【方法】以国家重点管理外来入侵物种名录中的入侵植物为研究对象,根据生物入侵的发生过程(传入、定殖、扩散、危害)构建了包括4个层次29个指标的外来物种入侵综合风险评估的指标体系,规范了风险指数的计算方法,系统评估了24种入侵植物沿南水北调输水通道向北扩散而入侵京津冀受水区的风险。【结果】紫茎泽兰和互花米草的入侵风险值(R)相对较低(R0.6),其余22种入侵植物的风险值均较高(R0.6),其中,喜旱莲子草、凤眼莲和大薸3种外来水生植物的入侵风险等级最高(R0.8)。【结论】南水北调工程可能会促进入侵植物向北扩张蔓延并最终入侵京津冀受水区。建议尽早开展监测预警工作,以控制入侵物种随南水北调工程的扩张蔓延,进而阻止或降低其对京津冀尤其是华北最大水源地——白洋淀和雄安新区生态环境的威胁。     

竞争和景观格局相互作用对外来入侵物种传播影响的动态模拟

通过中性景观模型和元胞自动机模型模拟了不同景观格局、不同竞争力和关键种群特征的外来入侵物种的传播动态,模拟结果表明:(1)竞争力强的外来入侵物种,可利用生境面积越大,集聚度越高,越有利于其入侵和传播,而对竞争力弱的外来入侵物种来说,可利用生境面积越小,越分散,越有利于其生存。竞争力强可以有效利用整块的高集聚度的资源,而弱竞争力的外来入侵物种为了逃避土著种的竞争往往趋向于分布在分散的小生境中;(2)可利用生境面积大于50%时,景观格局集聚度越小,竞争力弱的外来入侵物种适应环境的弛豫时间越长;(3)外来入侵物种的传播与种子产量呈正相关关系,与繁殖年龄呈负相关关系,拟合关系因景观格局和竞争而异;(4)平均迁移距离对外来入侵物种传播的影响最大,在管理过程中应根据不同的目标,不同的景观格局、竞争力和种群特征选择合适的管理措施。     

基于个体的空间显性模型和遥感技术模拟入侵植物扩张机制

基于个体的空间显性模型和遥感技术,以互花米草为例,模拟了自1997到2010年的种群扩张动态,揭示了土地利用变化与潮间带高程的影响;并通过全局敏感性分析揭示了种子扩散、成体存活率、有性和无性繁殖等种群统计学特征对互花米草种群扩张的相对重要性。研究结果发现:1)有性繁殖与无性繁殖共同决定互花米草种群快速扩张;2)潮间带高程和土地利用变化显著影响模型预测的精度,对互花米草种群扩张有非常重要的影响;3)成体存活率与种子长距离扩散是影响互花米草种群扩张速度最重要的因素;无性繁殖比有性繁殖对种群扩张的影响更大;种子长距离扩散比本地扩散更为重要,同时,小概率的种子长距离扩散事件对种群扩张有非常重要的影响。为了经济有效地控制外来入侵植物的扩张,应该抑制种子的长距离扩散和移除种子长距离扩散形成的位于入侵前沿的小斑块。     

网络理论在入侵生物学中的应用研究现状

生物入侵是一个动态有序的过程,其发生和危害存在异质性,通常由来源地、入侵地和它们之间的连接构成的系统中的自然、生物、社会等因素所决定。网络理论是研究复杂系统的一种新方法,本质是从复杂的信息中抽象出规律、揭示系统的结构特征共性。近20年,网络理论已被应用于生物入侵研究。本研究综述了网络理论在生物入侵研究中的应用进展,明确了主要的研究方向和前沿热点,认为:2000年以来国际上已开展的研究集中在评估外来物种入侵风险和入侵后对生态系统影响2个方面;外来物种随运输网络入侵的风险评估和景观连接性对入侵物种扩散的影响、外来物种入侵对本地物种间互作网络的影响及生态群落可入侵性是网络理论应用的热点;研究热点具有明显的时间发展特征,2013年以前多是对生态系统的影响,近10年来主要是风险评估。我国利用网络理论研究外来物种入侵较少且集中于对生态系统的危害,未来应加强对外来物种的时空定量传入和扩散风险评估,为我国制定和提升外来入侵物种早期监测预警、阻止新的入侵、抑制进一步扩散的管理措施提供依据。     

外来种互花米草入侵模式与爆发机制

互花米草（Spartina alterniflora Loisel）因其促淤造陆和消浪护堤作用显著而被许多国家引种,如今却在侵入地快速蔓延并呈现爆发趋势,对生态系统造成了极大危害,被认为是研究生物入侵生态学和遗传学的模式植物。从种群的入侵力、生态系统可入侵性和入侵通道3个方面探讨互花米草的爆发机制,研究结果表明高遗传分化和基因渗入能力是互花米草爆发的遗传基础,对逆境的高抗性和强竞争力是其快速扩张的保障,而高繁殖系数是互花米草爆发的源泉。我国互花米草种群的早期扩散人为影响超过了自然过程,快速扩张呈现出点源扩散和多点爆发的特点,从而为其种群控制带来困难,同时种子的跳跃式和连续式扩散在互花米草种群维持、更新和爆发中有重要作用,强有力的克隆生长能力也为互花米草种群的连续扩张提供了保障。现阶段要完全控制和根除互花米草是不实际的,但在及时预测预警的基础上,应用成本一效益分析方法,采取有序控制和综合开发利用的策略,仍可望妥善解决互花米草入侵所带来的负面效应。     

A conceptual framework for understanding arthropod predator and parasitoid invasions

Arthropods make up the largest group of invasive alien species (IAS) worldwide. Although invasion research has been biased towards alien plants and vertebrates, it has suggested potential mechanisms for the success of IAS and provided a theoretical framework for further investigation. Here we address key concepts from invasion biology that are essential to our understanding of the success of invasive alien arthropod predators and parasitoids including human intervention, environmental characteristics, propagule pressure, biological traits, and biological interactions. To gain a greater understanding of the factors most likely to influence the different stages of invasion (arrival, establishment, and spread) for alien arthropod predators and parasitoids, we use a comparative approach to compare and contrast the differential success of invasions by alien phytophagous and carnivorous arthropods. Insights gained from this comparison suggest that future research will require a multitrophic approach in order to enhance our understanding of invasions at higher trophic levels.     

Invasive spread in meta-food-webs depends on landscape structure,fertilization and species characteristics

Land use change and biological invasions collectively threaten biodiversity. Yet, few studies have addressed how altering the landscape structure and nutrient supply can promote biological invasions and particularly invasive spread (the spread of an invader from the place of introduction), or asked whether and how these factors interact with biotic interactions and invader properties. We here bridge this knowledge gap by providing a holistic network-based approach. Our approach combines a trophic network model with a spatial network model allowing us to test which combinations of abiotic and biotic factors can facilitate invasions and in particular invasive spread in food webs. We numerically simulated 6300 single-species invasions in clustered and random landscapes at different levels of nutrient supply. In total, our simulation experiment yielded 69% successful invasions – 71% in clustered landscapes and 66% in random landscapes, with the proportion of successful invasions increasing with nutrient supply. However, invasive spread was generally higher in random than in clustered landscapes. The latter can facilitate invasive spread within a habitat cluster, but prevent invasive spread between clusters. Low nutrient levels generally prevented the establishment of invasive species and their subsequent spread. However, successful invaders could have more severe impacts as they contribute more to total biomass density and species richness under such conditions. Good dispersal abilities drive the broad-scale spread of invasive species in fragmented landscapes. Our approach makes an important contribution towards a better understanding of what combination of landscape and invader properties can facilitate or prevent invasive spread in natural ecosystems. This should allow ecologists to more effectively predict and manage biological invasions.     

Geographical and taxonomic biases in invasion ecology

Invasive alien species come from most taxonomic groups, and invasion biology is searching for robust cross-taxon generalizations and principles. An analysis of 2,670 papers dealing with 892 invasive species showed that all major groups of invaders are well studied, but that most information on the mechanisms of invasion has emerged from work on a limited number of the most harmful invaders. A strong geographical bias, with Africa and Asia understudied, inhibits a balanced understanding of invasion, because we might be lacking knowledge of specific invasion mechanisms from poorly studied, regionally specific habitats. International cooperation is required to achieve a more geographically balanced picture of biological invasions. Invasive species with the greatest impact are best studied, but more studies of species that are naturalized but not (yet) invasive are needed to improve understanding of the mechanisms acting during the naturalization phase of invasions and leading to successful invasion.     

入侵植物的生理生态特性对碳积累的影响

随着国际贸易的发展和人们交往的增加以及全球环境的变化,生物种类在全球扩散的机会也大大增加,从而为生物入侵创造了机会。生物入侵不仅给农林牧生产造成损失,而且具有长期的生态学效应。外来种的成功入侵不是其自身某一个特性决定的,而是其特性与新的生境综合作用的结果。外来入侵种生理生态特性的研究对其预测和防治具有重要的意义。目前对入侵种生理生态特性的研究较少。已有的研究表明,与本地种相比入侵种可能通过提高光合能力、资源利用率、表型可塑性、化感作用,以及降低繁殖成本等增加植株碳积累,促进其入侵。但并不是所有的入侵种都同时具有这些特性。生境不同限制性资源不同,入侵机制就不同。成功的入侵种应该能够高效地利用生境中的限制性资源,并且能够较快地调节自身的生理特性以适应波动的资源环境。     

Physico‐chemical variables determining the invasion risk of freshwater habitats by alien mollusks and crustaceans

The aim of this study was to assess the invasion risk of freshwater habitats and determine the environmental variables that are most favorable for the establishment of alien amphipods, isopods, gastropods, and bivalves. A total of 981 sites located in streams and rivers in Germany. Therefore we analyzed presence–absence data of alien and indigenous amphipods, isopods, gastropods, and bivalves from 981 sites located in small to large rivers in Germany with regard to eight environmental variables: chloride, ammonium, nitrate, oxygen, orthophosphate, distance to the next navigable waterway, and maximum and minimum temperature. Degraded sites close to navigable waters were exposed to an increased invasion risk by all major groups of alien species. Moreover, invaded sites by all four groups of alien species were similar, whereas the sites where indigenous members of the four groups occurred were more variable. Increased temperature and chloride concentration as well as decreased oxygen concentration were identified as major factors for the invasibility of a site. Species‐specific analyses showed that chloride was among the three most predictive environmental variables determining species assemblage in all four taxonomic groups. Also distance to the next navigable waterways was similarly important. Additionally, the minimum temperature was among the most important variables for amphipods, isopods, and bivalves. The bias in the occurrence patterns of alien species toward similarly degraded habitats suggests that the members of all four major groups of freshwater alien species are a non‐random, more tolerant set of species. Their common tolerance to salinity, high temperature, and oxygen depletion may reflect that most alien species were spread in ballast water tanks, where strong selective pressures, particularly temperature fluctuations, oxygen depletion, and increased salinity may create a bottleneck for successful invasion. Knowledge on the major factors that influence the invasion risk of a habitat is needed to develop strategies to limit the spread of invasive species.     

Ecology of invasive mosquitoes: effects on resident species and on human health

Investigations of biological invasions focus on patterns and processes that are related to introduction, establishment, spread and impacts of introduced species. This review focuses on the ecological interactions operating during invasions by the most prominent group of insect vectors of disease, mosquitoes. First, we review characteristics of non-native mosquito species that have established viable populations, and those invasive species that have spread widely and had major impacts, testing whether biotic characteristics are associated with the transition from established non-native to invasive. Second, we review the roles of interspecific competition, apparent competition, predation, intraguild predation and climatic limitation as causes of impacts on residents or as barriers to invasion. We concentrate on the best-studied invasive mosquito, Aedes albopictus, evaluating the application of basic ecological theory to invasions by Aedes albopictus. We develop a model based on observations of Aedes albopictus for effects of resource competition and predation as barriers to invasion, evaluating which community and ecosystem characteristics favour invasion. Third, we evaluate the ways in which invasive mosquitoes have contributed to outbreaks of human and animal disease, considering specifically whether invasive mosquitoes create novel health threats, or modify disease transmission for existing pathogen-host systems.     

基于分子生物学方法的外来入侵物种入侵历史重构

生物入侵是一个世界性的问题。全球每年因生物入侵造成的损失超过1万亿美元。探究入侵物种在入侵地的入侵历史对了解生物入侵的生物生态学机制、制定阻截及防除措施有重要意义。分子标记方法的兴起和大规模应用打开了入侵生物入侵历史研究的新天地。采用分子标记的方法可鉴定入侵物种的种类、追溯其来源地、回溯其扩散路径、分析扩散模式及探究物种入侵过程中对入侵种群本身的变化及其对生态系统所造成的各种影响。分子标记的应用使得多个入侵物种的入侵历史得以重现。由于分子标记方法重构的入侵历史受采样范围、采用的分子标记的种类及数量等因素的影响,该方法呈现入侵历史是否是真实发生的入侵过程还存在争议。     

Searching for phylogenetic pattern in biological invasions

It has been suggested that alien species with close indigenous relatives in the introduced range may have reduced chances of successful establishment and invasion (Darwin's naturalization hypothesis). Studies trying to test this have in fact been addressing four different hypotheses, and the same data can support some while rejecting others. In this paper, we argue that the phylogenetic pattern will change depending on the spatial and phylogenetic scales considered. Expectations and observations from invasion biology and the study of natural communities are that at the spatial scale relevant to competitive interactions, closely related species will be spatially separated, whereas at the regional scale, species in the same genera or families will tend to co-occur more often than by chance. We also argue that patterns in the relatedness of indigenous and naturalized plants are dependent on the continental/island setting, spatial occupancy levels, and on the group of organisms under scrutiny. Understanding how these factors create a phylogenetic pattern in invasions will help us predict which groups are more likely to invade where, and should contribute to general ecological theory.     

Invasions by alien plant species of the agro-pastoral ecotone in northern China: Species-specific and environmental determinants

The establishment, reproduction, dispersal, and distribution of alien plants are affected by various factors during the transition from being newly introduced in a habitat to being invasive. In the agro-pastoral ecotone of northern China, comprising farmlands and natural grasslands, the biological characteristics of alien plant species were the key intrinsic factors (propagation characteristics and competitive ability), followed by such extrinsic factors as human interference and environmental heterogeneity. Among biological characteristics, the life form may be an important and useful indicator of the invasive ability of a species, and the risk of invasion is greater from alien species that are poisonous, inedible, and have traits that facilitate wide dispersal. Farmlands may serve as initial shelters for alien species, from which they spread into neighbouring habitats, whereas natural grassland may act as a barrier to plant invasions. Management practices detrimental to grasslands, including overgrazing, reclamation, and road construction, often facilitate the invasions; therefore, counter measures such as reseeding and a ban on grazing need special attention. Environmental factors including precipitation, nutrients, prevailing winds, fires, and topography may be other factors that promote or block the process of invasion. In studying ways of preventing or controlling such invasions, alien plants with short life cycle, prolific seed production, and strong competitiveness, deserve particular attention and so do human activities that may damage the environment and fragile habitats.     

Can behavioral and personality traits influence the success of unintentional species introductions?

Unintentional species invasions are instigated by human-mediated dispersal of individuals beyond their native range. Although most introductions fail at the first hurdle, a select subset pass through each stage of the introduction process (i.e., transport, introduction, establishment and spread) to become successful invaders. Efforts to identify the traits associated with invasion success have predominately focused on deliberate introductions, which essentially bypass the initial introduction stage. Here, we highlight how behavior influences the success or failure of unintentional species introductions across each stage of the introduction process, with a particular focus on transportation and initial establishment. In addition, we emphasize how recent advances in understanding of animal personalities and individual-level behavioral variation can help elucidate the mechanisms underlying the success of stowaways.