Summary Understanding the mechanisms by which invasive species affect native plants is a central challenge. Invasive plants have been shown to reduce pollinator visitation to natives and increase pollen quantity limitation. However, visitation and conspecific pollen delivery are the only two components of the pollination process; post-pollination interactions on the stigma (heterospecific pollen [HP] receipt) could intensify pre-pollination responses to invasion. Here, we used meta-analysis to test the hypotheses that invasive plants are more detrimental as HP donors than natives ones and that HP donors that are closely related to the recipients have stronger effects on fruit and seed production compared to distantly related ones. Invasive HP donors reduced fruit and seed production of recipients to a greater degree than native ones, and this was more intense for HP donors closely related to natives. Related donors were more detrimental overall. Synthesis . These results suggest that the total effect of invasive plants on native plant reproductive success could be greater than what is inferred from visitation and conspecific pollen transfer alone. Furthermore, these results indicate that invasive species can reduce reproductive success of native species even if pollinator visitation rates remain unaltered. Thus, we highlight the need to evaluate pre- and post-pollination processes in order to fully understand the potential effects of invasive species on the reproductive success and maintenance of native plant populations.

Most studies of plant-animal mutualisms involve a small number of species. There is almost no information on the structural organization of species-rich mutualistic networks despite its potential importance for the maintenance of diversity. Here we analyze 52 mutualistic networks and show that they are highly nested; that is, the more specialist species interact only with proper subsets of those species interacting with the more generalists. This assembly pattern generates highly asymmetrical interactions and organizes the community cohesively around a central core of interactions. Thus, mutualistic networks are neither randomly assembled nor organized in compartments arising from tight, parallel specialization. Furthermore, nestedness increases with the complexity (number of interactions) of the network: for a given number of species, communities with more interactions are significantly more nested. Our results indicate a nonrandom pattern of community organization that may be relevant for our understanding of the organization and persistence of biodiversity.

The mutualistic interactions between plants and their pollinators or seed dispersers have played a major role in the maintenance of Earth's biodiversity. To investigate how coevolutionary interactions are shaped within species-rich communities, we characterized the architecture of an array of quantitative, mutualistic networks spanning a broad geographic range. These coevolutionary networks are highly asymmetric, so that if a plant species depends strongly on an animal species, the animal depends weakly on the plant. By using a simple dynamical model, we showed that asymmetries inherent in coevolutionary networks may enhance long-term coexistence and facilitate biodiversity maintenance.

Background Network analyses of plant-animal interactions hold valuable biological information. They are often used to quantify the degree of specialization between partners, but usually based on qualitative indices such as 'connectance' or number of links. These measures ignore interaction frequencies or sampling intensity, and strongly depend on network size. Results Here we introduce two quantitative indices using interaction frequencies to describe the degree of specialization, based on information theory. The first measure (d') describes the degree of interaction specialization at the species level, while the second measure (H2') characterizes the degree of specialization or partitioning among two parties in the entire network. Both indices are mathematically related and derived from Shannon entropy. The species-level index d' can be used to analyze variation within networks, while H2' as a network-level index is useful for comparisons across different interaction webs. Analyses of two published pollinator networks identified differences and features that have not been detected with previous approaches. For instance, plants and pollinators within a network differed in their average degree of specialization (weighted mean d'), and the correlation between specialization of pollinators and their relative abundance also differed between the webs. Rarefied sampling effort in both networks and null model simulations suggest that H2' is not affected by network size or sampling intensity. Conclusion Quantitative analyses reflect properties of interaction networks more appropriately than previous qualitative attempts, and are robust against variation in sampling intensity, network size and symmetry. These measures will improve our understanding of patterns of specialization within and across networks from a broad spectrum of biological interactions.

61 The strength of the self-incompatibility (SI) response in Senecio squalidus was measured across its British range. Geographic variation in SI was investigated and the extent and inheritance of pseudo-self-compatibility (PSC) and inbreeding depression were determined. 61 Mean self-fruit-set per capitulum was calculated for individuals and sample populations. The heritability of PSC and the magnitude of inbreeding depression were assessed by comparing selfing rates and fitness trait values between SI and PSC parent-progeny lines. 61 SI was found to be strongly expressed in S. squalidus throughout its British range, with only 3.1% of the individuals sampled showing PSC. This PSC had relatively low heritability with stronger expression of SI in selfed progeny relative to PSC parents. Inbreeding depression was shown to be great in S. squalidus, with mean life history stage values ranging from 0.18 to 0.25. 61 The strength of SI in S. squalidus appears not to have weakened in response to its rapid colonization of Britain. The avoidance of inbreeding depression is likely to be the primary factor maintaining strong SI in this successful colonizing species.

090004 If pollinators or compatible mates are scarce, plants in small populations may be pollen-limited and consequently produce fewer offspring. However, determining the relative importance of the genetic vs ecological mechanisms limiting successful pollination is challenging. 090004 We explored the relationships among population size, population connectivity, pollinator visitation, allozyme diversity, mate availability (measured as percent compatible crosses among plants within a population), and pollen limitation in 12 populations ( N = 39090009885274) of the self-incompatible plant Hymenoxys herbacea in Ontario, Canada. 090004 Unexpectedly, small populations had more insect flower visitors per capitulum than large populations. Consistent with the effects of genetic drift, both allozyme polymorphism and mate availability decreased with decreasing population size. Pollen limitation was low and significant in only one population and could not be predicted based on knowledge of population size, connectivity, compatible mate availability, or pollinator visitation. 090004 Population size had detectable effects on both pollinator activity and mate availability. However, because the effect of population size was complementary on these two potentially limiting mechanisms, this threatened plant was rarely pollen-limited.

报道了中国大陆归化植物新记录刺毛峨参(Anthriscus caucalis M.Bieb.)和印加孔雀草(Tagetes minuta L.),并进行了形态描述,提供了凭证标本和活植物照片。

报道了中国大陆归化植物新记录刺毛峨参(Anthriscus caucalis M.Bieb.)和印加孔雀草(Tagetes minuta L.),并进行了形态描述,提供了凭证标本和活植物照片。

Plant invasions can have large effects on ecosystem services. Some plant invaders were introduced specifically to restore key services to ecosystems, and other invaders are having unintended, detrimental effects on services, such as the quantity and quality of water delivered, flood control, erosion control, and food production. Many ecosystem services are difficult to measure directly, and although there are extensive studies on plant invaders and ecosystem processes, a number of challenges prevent us from confidently extrapolating those processes as proxies for services. To extrapolate local, short-term measures of processes to ecosystem services, we must: (1) determine which processes are the key contributors to a service, (2) assess how multiple processes interact to provide a given service, (3) determine how vegetation types and species affect those processes, and (4) explicitly assess how ecosystem services and their controls vary over space and time, including reliance of ecosystem services on u201chot spotsu201d and u201chot momentsu201d and a minimum size of a vegetation type in the landscape. A given invader can have positive effects on some services and negative effects on others. It is important to consider that, in some systems, shifting environmental conditions may no longer support native species and that invasive species may be critical contributors to the resilience of ecosystem services.

植物与传粉者之间相互作用, 构成了复杂的传粉网络。近年来, 社会网络分析技术的发展使得复杂生态网络的研究成为可能。从群落水平上研究植物与传粉者之间的互惠关系, 为理解群落的结构和动态以及花部特征的演化提供了全新的视角。传粉网络的嵌套结构说明自然界的传粉服务存在冗余, 而且是相对泛化的物种主导了传粉。在多年或者多季度的传粉网络中, 虽然有很高的物种替换率, 但是其网络结构仍然保持相对稳定, 说明传粉网络对干扰有很强的抗性。尽管有关网络结构和动态的研究逐渐增多, 但传粉网络维持的机制仍不清楚。网络结构可以部分由花部特征与传粉者的匹配来解释, 也受到系统发生的制约, 影响因素还包括群落构建的时间和物种多样性, 以及物种在群落中的位置。开展大尺度群落动态的研究, 为探索不同时间尺度、不同物种多样性水平上的传粉网络的生态学意义提供了条件。但已有的研究仍存在不足, 比如基于访问观察的网络无法准确衡量传粉者的 访问效率和植物间的花粉流动, 以及结果受到调查精度区域研究不平衡的制约等。目前的研究只深入到传粉者携带花粉构成成分的水平, 传粉者访问植物的网络不能代表植物的整个传粉过程。因此, 研究应当更多地深入到物种之间关系对有性生殖的切实影响上。

植物与传粉者之间相互作用, 构成了复杂的传粉网络。近年来, 社会网络分析技术的发展使得复杂生态网络的研究成为可能。从群落水平上研究植物与传粉者之间的互惠关系, 为理解群落的结构和动态以及花部特征的演化提供了全新的视角。传粉网络的嵌套结构说明自然界的传粉服务存在冗余, 而且是相对泛化的物种主导了传粉。在多年或者多季度的传粉网络中, 虽然有很高的物种替换率, 但是其网络结构仍然保持相对稳定, 说明传粉网络对干扰有很强的抗性。尽管有关网络结构和动态的研究逐渐增多, 但传粉网络维持的机制仍不清楚。网络结构可以部分由花部特征与传粉者的匹配来解释, 也受到系统发生的制约, 影响因素还包括群落构建的时间和物种多样性, 以及物种在群落中的位置。开展大尺度群落动态的研究, 为探索不同时间尺度、不同物种多样性水平上的传粉网络的生态学意义提供了条件。但已有的研究仍存在不足, 比如基于访问观察的网络无法准确衡量传粉者的 访问效率和植物间的花粉流动, 以及结果受到调查精度区域研究不平衡的制约等。目前的研究只深入到传粉者携带花粉构成成分的水平, 传粉者访问植物的网络不能代表植物的整个传粉过程。因此, 研究应当更多地深入到物种之间关系对有性生殖的切实影响上。

When exotic plant species share pollinators with native species, competition for pollination may lower the reproductive success of natives by reducing the frequency and/or quality of visits they receive. Exotic species often become numerically dominant in plant communities, and the relative abundance of these potential competitors for pollination may be an important determinant of their effects on the pollination and reproductive success of co-occurring native species. Our study experimentally tests whether the presence and abundance of an invasive exotic, Lythrum salicaria L. (Lythraceae), influences reproductive success of a co-flowering native species, Mimulus ringens L. (Phrymaceae). We also examine the mechanisms of competition for pollination and how they may be altered by changes in competitor abundance. We found that the presence of Lythrum salicaria lowered mean seed number in Mimulus ringens fruits. This effect was most pronounced when the invasive competitor was highly abundant, decreasing the number of seeds per fruit by 40% in 2006 and 33% in 2007. Reductions in the number of seeds per fruit were likely due to reduced visit quality resulting from Mimulus pollen loss when bees foraged on neighboring Lythrum plants. This study suggests that visit quality to natives may be influenced by the presence and abundance of invasive flowering plants.

Abstract Through competition for pollinators, invasive plants may suppress native flora. Community-level studies provide an integrative assessment of invasion impacts and insights into factors that influence the vulnerability of different native species. We investigated effects of the non-native herb Lythrum salicaria on pollination of native species in 14 fens of the eastern United States. We compared visitors per flower for 122 native plant species in invaded and uninvaded fens and incorporated a landscape-scale experiment, removing L. salicaria flowers from three of the invaded fens. Total flower densities were more than three times higher in invaded than uninvaded or removal sites when L. salicaria was blooming. Despite an increase in number of visitors with number of flowers per area, visitors per native flower declined with increasing numbers of flowers. Therefore, L. salicaria invasion depressed visitation to native flowers. In removal sites, visitation to native flowers was similar to uninvaded sites, confirming the observational results and also suggesting that invasion had not generated a persistent buildup of visitor populations. To study species-level impacts, we examined effects of invasion on visitors per flower for the 36 plant species flowering in both invaded and uninvaded fens. On average, the effect of invasion represented about a 20% reduction in visits per flower. We measured the influence of plant traits on vulnerability to L. salicaria invasion using meta-analysis. Bilaterally symmetrical flowers experienced stronger impacts on visitation, and similarity in flower color to L. salicaria weakly intensified competition with the invader for visitors. Finally, we assessed the reproductive consequences of competition with the invader in a dominant flowering shrub, Dasiphora fruticosa. Despite the negative effect of invasion on pollinator visitation in this species, pollen limitation of seed production was not stronger in invaded than uninvaded sites, suggesting little impact of competition for pollinators on its population demography. Negative effects on pollination of native plants by this copiously-flowering invader appeared to be mediated by increases in total flower density that were not matched by increases in pollinator density. The strength of impact was modulated across native species by their floral traits and reproductive ecology. This article is protected by copyright. All rights reserved.

Invasive alien plant species are frequently characterized by a high fecundity. However, because suitable pollinators and/or mates may be absent in the new range, it is not clear how they achieve high seed production. According to Baker Law, species capable of uniparental reproduction are more likely to establish after long-distance dispersal than species that rely on suitable mates and pollinators. To test whether self-compatible species, and particularly species capable of autonomous seed set, are more likely to establish and spread, we experimentally assessed the breeding systems of 12 species of Asteraceae that are invasive in China. Among these 12 species of Asteraceae, the percentages of self-compatible species (66.7%) and species capable of autonomous seed set (83.3%), which included self-fertilizing and apomictic species, were significantly larger than expected from the percentages of such species in global data sets of Asteraceae (36.8% and 46.0%, respectively). Furthermore, the number of Chinese provinces in which the invasive alien species occur was significantly positively correlated with the proportion seed set on bagged capitula (i.e. with the degree of autonomous seed set). Among 36 species of Asteraceae that are invasive in China and for which we found breeding-system data in the literature, we also found a higher than expected percentage of self-compatible species (65.7%), and that these self-compatible species are more widespread in China than self-incompatible species. These results support the predictions of Baker Law that self-compatible species, and particularly those capable of autonomous seed production, are more likely to establish and spread in a new range. Therefore, breeding systems of plants should be included as one of the key elements in risk assessment protocols for plant invasiveness.

Abstract Non-native species cause changes in the ecosystems to which they are introduced. These changes, or some of them, are usually termed impacts; they can be manifold and potentially damaging to ecosystems and biodiversity. However, the impacts of most non-native species are poorly understood, and a synthesis of available information is being hindered because authors often do not clearly define impact. We argue that explicitly defining the impact of non-native species will promote progress toward a better understanding of the implications of changes to biodiversity and ecosystems caused by non-native species; help disentangle which aspects of scientific debates about non-native species are due to disparate definitions and which represent true scientific discord; and improve communication between scientists from different research disciplines and between scientists, managers, and policy makers. For these reasons and based on examples from the literature, we devised seven key questions that fall into 4 categories: directionality, classification and measurement, ecological or socio-economic changes, and scale. These questions should help in formulating clear and practical definitions of impact to suit specific scientific, stakeholder, or legislative contexts. Definiendo el Impacto de las Especies No-Nativas Resumen Las especies no-nativas pueden causar cambios en los ecosistemas donde son introducidas. Estos cambios, o algunos de ellos, usualmente se denominan como impactos ; estos pueden ser variados y potencialmente da09inos para los ecosistemas y la biodiversidad. Sin embargo, los impactos de la mayoría de las especies no-nativas están pobremente entendidos y una síntesis de información disponible se ve obstaculizada porque los autores continuamente no definen claramente impacto . Discutimos que definir explícitamente el impacto de las especies no-nativas promoverá el progreso hacia un mejor entendimiento de las implicaciones de los cambios a la biodiversidad y los ecosistemas causados por especies no-nativas; ayudar a entender cuáles aspectos de los debates científicos sobre especies no-nativas son debidos a definiciones diversas y cuáles representan un verdadero desacuerdo científico; y mejorar la comunicación entre científicos de diferentes disciplinas y entre científicos, administradores y quienes hacen las políticas. Por estas razones y basándonos en ejemplos tomados de la literatura, concebimos siete preguntas clave que caen en cuatro categorías: direccionalidad, clasificación y medida, cambios ecológicos o socio-económicos, y escala. Estas preguntas deberían ayudar en la formulación de definiciones claras y prácticas del impacto para encajar mejor con contextos científicos, de las partes interesadas o legislativos específicos.

生物入侵已对入侵区的生态环境、社会经济和人类健康造成了严重的威胁,成为了21世纪五大全球性环境问题之一。本文回顾了2000年以来,中国生物入侵研究领域尤其是入侵种的多样性与格局、入侵机制及生态学效应、管理与控制等方面所取得的重要进展,讨论了需进一步加强研究的领域,以期为进一步拓展该领域研究的广度和深度、为我国的生物入侵预警预防和科学治理提供参考。据初步研究,中国的入侵种数量已达529种,其中陆生植物、陆生无脊椎动物和微生物为主要入侵类群;原产地以北美洲和南美洲为主;经济发达和气候温暖湿润的东部和南部省份入侵态势明显较西部和北部省份严重;随着中国经济的进一步发展,生物入侵问题将可能更加严峻。外来种的成功入侵是其内禀优势、资源机遇和人为干扰共同作用的结果;其中,表型可塑性、适应性进化、天敌释放、种间互利或偏利共生和新化感作用等因素对入侵起到了关键作用。生物入侵已对中国土著生态系统的生物多样性和生态系统服务功能造成了严重影响,打破了生态系统的固有平衡,危害或威胁到中国的农林牧渔业生产、交通航运、环境、人类健康和公共设施安全。针对生物入侵的管理与控制,中国加强了包括检测监测、风险分析、生物防治、扩散阻断、根治灭除和生态恢复等技术体系的研究和实施,并初步控制了一些重要入侵种的扩张。中国生物入侵需要在全境性科学考察、生物入侵的遗传学、基因组学、生态系统影响、全球变化和管理与控制技术创新等领域进一步加强跨领域的交叉合作和系统研究。

生物入侵已对入侵区的生态环境、社会经济和人类健康造成了严重的威胁,成为了21世纪五大全球性环境问题之一。本文回顾了2000年以来,中国生物入侵研究领域尤其是入侵种的多样性与格局、入侵机制及生态学效应、管理与控制等方面所取得的重要进展,讨论了需进一步加强研究的领域,以期为进一步拓展该领域研究的广度和深度、为我国的生物入侵预警预防和科学治理提供参考。据初步研究,中国的入侵种数量已达529种,其中陆生植物、陆生无脊椎动物和微生物为主要入侵类群;原产地以北美洲和南美洲为主;经济发达和气候温暖湿润的东部和南部省份入侵态势明显较西部和北部省份严重;随着中国经济的进一步发展,生物入侵问题将可能更加严峻。外来种的成功入侵是其内禀优势、资源机遇和人为干扰共同作用的结果;其中,表型可塑性、适应性进化、天敌释放、种间互利或偏利共生和新化感作用等因素对入侵起到了关键作用。生物入侵已对中国土著生态系统的生物多样性和生态系统服务功能造成了严重影响,打破了生态系统的固有平衡,危害或威胁到中国的农林牧渔业生产、交通航运、环境、人类健康和公共设施安全。针对生物入侵的管理与控制,中国加强了包括检测监测、风险分析、生物防治、扩散阻断、根治灭除和生态恢复等技术体系的研究和实施,并初步控制了一些重要入侵种的扩张。中国生物入侵需要在全境性科学考察、生物入侵的遗传学、基因组学、生态系统影响、全球变化和管理与控制技术创新等领域进一步加强跨领域的交叉合作和系统研究。

Land degradation results in declining biodiversity and the disruption of ecosystem functioning worldwide, particularly in the tropics. Vegetation restoration is a common tool used to mitigate these impacts and increasingly aims to restore ecosystem functions rather than species diversity. However, evidence from community experiments on the effect of restoration practices on ecosystem functions is scarce. Pollination is an important ecosystem function and the global decline in pollinators attenuates the resistance of natural areas and agro-environments to disturbances. Thus, the ability of pollination functions to resist or recover from disturbance (that is, the functional resilience) may be critical for ensuring a successful restoration process. Here we report the use of a community field experiment to investigate the effects of vegetation restoration, specifically the removal of exotic shrubs, on pollination. We analyse 64 plant-pollinator networks and the reproductive performance of the ten most abundant plant species across four restored and four unrestored, disturbed mountaintop communities. Ecosystem restoration resulted in a marked increase in pollinator species, visits to flowers and interaction diversity. Interactions in restored networks were more generalized than in unrestored networks, indicating a higher functional redundancy in restored communities. Shifts in interaction patterns had direct and positive effects on pollination, especially on the relative and total fruit production of native plants. Pollinator limitation was prevalent at unrestored sites only, where the proportion of flowers producing fruit increased with pollinator visitation, approaching the higher levels seen in restored plant communities. Our results show that vegetation restoration can improve pollination, suggesting that the degradation of ecosystem functions is at least partially reversible. The degree of recovery may depend on the state of degradation before restoration intervention and the proximity to pollinator source populations in the surrounding landscape. We demonstrate that network structure is a suitable indicator for pollination quality, highlighting the usefulness of interaction networks in environmental management.

The pollination of flowering plants by animals represents a critical ecosystem service of great value to humanity, both monetary and otherwise. However, the need for active conservation of pollination interactions is only now being appreciated. Pollination systems are under increasing threat from anthropogenic sources, including fragmentation of habitat, changes in land use, modern agricultural practices, use of chemicals such as pesticides and herbicides, and invasions of non-native plants and animals. Honeybees, which themselves are non-native pollinators on most continents, and which may harm native bees and other pollinators, are nonetheless critically important for crop pollination. Recent declines in honeybee numbers in the United States and Europe bring home the importance of healthy pollination systems, and the need to further develop native bees and other animals as crop pollinators. The "pollination crisis" that is evident in declines of honeybees and native bees, and in damage to webs of plant-pollinator interaction, may be ameliorated not only by cultivation of a diversity of crop pollinators, but also by changes in habitat use and agricultural practices, species reintroductions and removals, and other means. In addition, ecologists must redouble efforts to study basic aspects of plant-pollinator interactions if optimal management decisions are to be made for conservation of these interactions in natural and agricultural ecosystems.

传粉者是重要的生态功能提供者,在维持稳定的生态系统和高效的农业生产力中发挥着重要作用。因此,传粉网络的构建和监测工作对评价生态系统平衡和调控农业生产至关重要。该工作的基础就是通过对传粉者及植物的物种鉴定构建其相关性。传统的形态学物种鉴定对分类学专家的专业知识、时间和经验都提出较高的要求。DNA条形码和高通量测序技术(high-throughput sequencing,HTS)的发展及其在传粉网络研究中的应用,提供了高效、准确鉴定传粉者与植物的方法,大大提高了传粉网络构建的效率。本文阐述了传粉网络研究相关的研究方法和技术进展,并提出利用高通量测序技术结合无PCR扩增(PCR-free)的"超级条形码"技术,有望实现以更高的灵敏度和分辨率对混合物种样品进行定性及相对定量的监测。该方法的有效性已在其他生物多样性研究中得以验证,在传粉网络研究中虽处于初始阶段,但应用前景广阔。

传粉者是重要的生态功能提供者,在维持稳定的生态系统和高效的农业生产力中发挥着重要作用。因此,传粉网络的构建和监测工作对评价生态系统平衡和调控农业生产至关重要。该工作的基础就是通过对传粉者及植物的物种鉴定构建其相关性。传统的形态学物种鉴定对分类学专家的专业知识、时间和经验都提出较高的要求。DNA条形码和高通量测序技术(high-throughput sequencing,HTS)的发展及其在传粉网络研究中的应用,提供了高效、准确鉴定传粉者与植物的方法,大大提高了传粉网络构建的效率。本文阐述了传粉网络研究相关的研究方法和技术进展,并提出利用高通量测序技术结合无PCR扩增(PCR-free)的"超级条形码"技术,有望实现以更高的灵敏度和分辨率对混合物种样品进行定性及相对定量的监测。该方法的有效性已在其他生物多样性研究中得以验证,在传粉网络研究中虽处于初始阶段,但应用前景广阔。

Studies of pairwise interactions have shown that an alien plant can affect the pollination of a native plant, this effect being mediated by shared pollinators. Here we use a manipulative field experiment, to investigate the impact of the alien plant Impatiens glandulifera on an entire community of coflowering native plants. Visitation and pollen transport networks were constructed to compare replicated I. glandulifera invaded and I. glandulifera removal plots. Invaded plots had significantly higher visitor species richness, visitor abundance and flower visitation. However, the pollen transport networks were dominated by alien pollen grains in the invaded plots and consequently higher visitation may not translate in facilitation for pollination. The more generalized insects were more likely to visit the alien plant, and Hymenoptera and Hemiptera were more likely to visit the alien than Coleoptera. Our data indicate that generalized native pollinators can provide a pathway of integration for alien plants into native visitation systems.

Floral displays of invasive plants have positive and negative impacts on native plant pollination. Invasive plants may also decrease irradiance, which can lead to reduced pollination of native plants. The effects of shade and flowers of invasive plant species on native plant pollination will depend on overlap in flowering phenologies. We examined the effect of the invasive shrub Lonicera maackii on female reproductive success of the native herb Hydrophyllum macrophyllum at two sites: one with asynchronous flowering phenologies (slight overlap) and one with synchronous (complete overlap). At each site, we measured light availability, pollinator visitation, pollen deposition, and seed set of potted H. macrophyllum in the presence and absence of L. maackii. At both sites, understory light levels were lower in plots containing L. maackii. At the asynchronous site, H. macrophyllum received fewer pollinator visits in the presence of L. maackii, suggesting shade from L. maackii reduced visitation to H. macrophyllum. Despite reduced visitation, H. macrophyllum seed set did not differ between treatments. At the synchronous site, H. macrophyllum received more pollinator visits and produced more seeds per flower in the presence of co-flowering L. maackii compared to plots in which L. maackii was absent, and conspecific pollen deposition was positively associated with seed set. Our results support the hypothesis that co-flowering L. maackii shrubs facilitated pollination of H. macrophyllum, thereby mitigating the negative impacts of shade, leading to increased seed production. Phenological overlap appears to influence pollinator-mediated interactions between invasive and native plants and may alter the direction of impact of L. maackii on native plant pollination.

In natural communities, species and their interactions are often organized as nonrandom networks, showing distinct and repeated complex patterns. A prevalent, but poorly explored pattern is ecological modularity, with weakly interlinked subsets of species (modules), which, however, internally consist of strongly connected species. The importance of modularity has been discussed for a long time, but no consensus on its prevalence in ecological networks has yet been reached. Progress is hampered by inadequate methods and a lack of large datasets. We analyzed 51 pollination networks including almost 10,000 species and 20,000 links and tested for modularity by using a recently developed simulated annealing algorithm. All networks with >150 plant and pollinator species were modular, whereas networks with <50 species were never modular. Both module number and size increased with species number. Each module includes one or a few species groups with convergent trait sets that may be considered as coevolutionary units. Species played different roles with respect to modularity. However, only 15% of all species were structurally important to their network. They were either hubs (i.e., highly linked species within their own module), connectors linking different modules, or both. If these key species go extinct, modules and networks may break apart and initiate cascades of extinction. Thus, species serving as hubs and connectors should receive high conservation priorities.

Mutualistic interactions between plants and animals promote integration of invasive species into native communities. In turn, the integrated invaders may alter existing patterns of mutualistic interactions. Here we simultaneously map in detail effects of invaders on parameters describing the topology of both plant-pollinator (bi-modal) and plant-plant (uni-modal) networks. We focus on the invader Opuntia spp., a cosmopolitan alien cactus. We compare two island systems: Tenerife (Canary Islands) and Menorca (Balearic Islands). Opuntia was found to modify the number of links between plants and pollinators, and was integrated into the new communities via the most generalist pollinators, but did not affect the general network pattern. The plant uni-modal networks showed disassortative linkage, i.e. species with many links tended to connect to species with few links. Thus, by linking to generalist natives, Opuntia remained peripheral to network topology, and this is probably why native network properties were not affected at least in one of the islands. We conclude that the network analytical approach is indeed a valuable tool to evaluate the effect of invaders on native communities.

Wild and managed pollinators provide a wide range of benefits to society in terms of contributions to food security, farmer and beekeeper livelihoods, social and cultural values, as well as the maintenance of wider biodiversity and ecosystem stability. Pollinators face numerous threats, including changes in land-use and management intensity, climate change, pesticides and genetically modified crops, pollinator management and pathogens, and invasive alien species. There are well-documented declines in some wild and managed pollinators in several regions of the world. However, many effective policy and management responses can be implemented to safeguard pollinators and sustain pollination services.

Previous studies have examined an association between reproductive success and pollination biology of rare versus widespread species through pair-wise comparisons of native and invasive congeners or rare and common congeners. To determine the importance of reproductive success and pollination biology for an invasive thistle, Cirsium vulgare , we compared it in its invaded range to five, co-occurring native Cirsium species that range from rare to common. Native study species include C. fontinale var. fontinale , C. andrewsii , C. brevistylum , C. occidentale , and C. quercetorum . We compared all species鈥 reproductive success, insect visitation rate and composition, autonomous self-pollination, and level of pollen limitation in multiple populations. Species differed in their reproductive success; the invasive C. vulgare produced more flower heads per plant than most native species. C. vulgare attracted more visitors than its congeners. In addition, reproductive success and insect visitation significantly varied between populations within species, mainly due to aphid infestation in one population of C. occidentale . Unlike the rare species ( C. fontinale and andrewsii ), C. vulgare did not require a pollinator for high-levels of seed production. The remaining native species set fewer seeds than C. vulgare without a pollinator. However, differences in insect visitation and autonomous self-pollination did not lead to differences in pollen limitation across species or between populations. This result suggests that factors other than pollination biology determine the difference in reproductive success of these species. However, high levels of autonomous self-pollination and generalist insect visitation may allow the invasive C. vulgare to easily establish new populations from low numbers of propagules. Our study provides one contrast that should build towards a larger comparative analysis to examine general patterns in the relationship between reproductive success, pollination biology, rare and invasive species, and our ability to predict biological invasions in introduced species.

Abstract PREMISE OF THE STUDY: Melissopalynology, the identification of bee-collected pollen, provides insight into the flowers exploited by foraging bees. Information provided by melissopalynology could guide floral enrichment efforts aimed at supporting pollinators, but it has rarely been used because traditional methods of pollen identification are laborious and require expert knowledge. We approach melissopalynology in a novel way, employing a molecular method to study the pollen foraging of honey bees (Apis mellifera) in a landscape dominated by field crops, and compare these results to those obtained by microscopic melissopalynology. 61 METHODS: Pollen was collected from honey bee colonies in Madison County, Ohio, USA, during a two-week period in midspring and identified using microscopic methods and ITS2 metabarcoding. 61 RESULTS: Metabarcoding identified 19 plant families and exhibited sensitivity for identifying the taxa present in large and diverse pollen samples relative to microscopy, which identified eight families. The bulk of pollen collected by honey bees was from trees (Sapindaceae, Oleaceae, and Rosaceae), although dandelion (Taraxacum officinale) and mustard (Brassicaceae) pollen were also abundant. 61 DISCUSSION: For quantitative analysis of pollen, using both metabarcoding and microscopic identification is superior to either individual method. For qualitative analysis, ITS2 metabarcoding is superior, providing heightened sensitivity and genus-level resolution.

理解入侵生物的繁殖策略是阐明生物入侵机制的一个重要方面。入侵植物常表现出一些共同的繁殖特征,如以两性花为主的性系统、自动自交为主的繁育系统或不依赖传粉媒介的无融合生殖和无性繁殖以及高生殖投资的资源配置策略等。成功入侵的外来植物通过影响本土的传粉者,在种群和群落水平上影响本土植物的有性繁殖,甚至促使某些本土植物在繁殖对策和表型性状上发生快速转变。目前,入侵植物繁殖策略及其生态效应的研究多侧重于入侵种的快速演化,而有关外来植物与本土植物间的相互影响及其可能存在的协同适应研究还较为缺乏。探讨本土植物在外来种入侵压力下的繁殖对策和响应机制,将丰富人们对物种间竞争、共存及群落构建等机制的深入了解。从繁殖和适应的角度探求入侵植物与本土植物之间的复杂关系,将有助于解析生物入侵的机制及人类干扰下的物种演化规律,也为预测和防控入侵植物提供科学依据。

理解入侵生物的繁殖策略是阐明生物入侵机制的一个重要方面。入侵植物常表现出一些共同的繁殖特征,如以两性花为主的性系统、自动自交为主的繁育系统或不依赖传粉媒介的无融合生殖和无性繁殖以及高生殖投资的资源配置策略等。成功入侵的外来植物通过影响本土的传粉者,在种群和群落水平上影响本土植物的有性繁殖,甚至促使某些本土植物在繁殖对策和表型性状上发生快速转变。目前,入侵植物繁殖策略及其生态效应的研究多侧重于入侵种的快速演化,而有关外来植物与本土植物间的相互影响及其可能存在的协同适应研究还较为缺乏。探讨本土植物在外来种入侵压力下的繁殖对策和响应机制,将丰富人们对物种间竞争、共存及群落构建等机制的深入了解。从繁殖和适应的角度探求入侵植物与本土植物之间的复杂关系,将有助于解析生物入侵的机制及人类干扰下的物种演化规律,也为预测和防控入侵植物提供科学依据。

本文探讨了外来入侵生物的概念及其在我国的危害状况、入侵原因 ,提出了外来入侵生物的预防及管理对策。随着国际贸易往来和旅游业的发展 ,生物入侵在我国不断加剧 ,正在成为威胁我国生物多样性与生态环境的重要因素之一。外来入侵种的生态代价是造成本地物种多样性不可弥补的消失以及物种的灭绝 ,其经济代价是农林牧渔业产量与质量的惨重损失与高额的防治费用。生物入侵在我国大部分是由于人为因素引起的。这些因素包括 :缺乏对引进种的利益与风险进行评估、淡薄的生态意识与不顾生态后果的经济利益驱使下的盲目引进、缺乏严格的科学监管体系或监管不力、缺乏全面检疫的体系与机制。外来入侵生物的综合性与系统性研究已成为当今我国生态环境保护、农业生产和经济可持续发展的重大研究领域。我国对外来入侵生物的预防与管理应着重于国家能力、研究能力、监测与管理能力三大体系的建设上。根据我国国情和目前的紧急现状应制定出优先行动计划。对特定外来种的入侵生物学基础研究、特定生态系统或地理区域入侵种现状及影响的关键评估研究、特定外来入侵生物对生态环境影响的风险评估体系及经济损失的模式研究、发展控制外来有害生物的环保型技术与方法研究、外来生物受控制后生态系统的恢复与栖息生境的复

本文探讨了外来入侵生物的概念及其在我国的危害状况、入侵原因 ,提出了外来入侵生物的预防及管理对策。随着国际贸易往来和旅游业的发展 ,生物入侵在我国不断加剧 ,正在成为威胁我国生物多样性与生态环境的重要因素之一。外来入侵种的生态代价是造成本地物种多样性不可弥补的消失以及物种的灭绝 ,其经济代价是农林牧渔业产量与质量的惨重损失与高额的防治费用。生物入侵在我国大部分是由于人为因素引起的。这些因素包括 :缺乏对引进种的利益与风险进行评估、淡薄的生态意识与不顾生态后果的经济利益驱使下的盲目引进、缺乏严格的科学监管体系或监管不力、缺乏全面检疫的体系与机制。外来入侵生物的综合性与系统性研究已成为当今我国生态环境保护、农业生产和经济可持续发展的重大研究领域。我国对外来入侵生物的预防与管理应着重于国家能力、研究能力、监测与管理能力三大体系的建设上。根据我国国情和目前的紧急现状应制定出优先行动计划。对特定外来种的入侵生物学基础研究、特定生态系统或地理区域入侵种现状及影响的关键评估研究、特定外来入侵生物对生态环境影响的风险评估体系及经济损失的模式研究、发展控制外来有害生物的环保型技术与方法研究、外来生物受控制后生态系统的恢复与栖息生境的复

Examining variations in pollinator effectiveness can enhance our understanding of how pollinators and plants interact. Pollen deposition and seed production after a single visit by a pollinator are often used to estimate pollinator effectiveness. However, seed production is not always directly related to pollen deposition because not all pollen grains that are deposited on a stigma are compatible or conspecific. In the field, we tested pollinator effectiveness based on pollen deposition and the resulting seed production after single visits by different pollinator groups in a gynodieocious alpine plant Cyananthus delavayi (Campanulaceae). Our results showed that mean pollen deposition was generally inconsistent with mean seed production when comparisons were performed among different pollinator groups and sexes. In general, the correlations were not significant between pollen deposition and seed production in both perfect and female flowers after single visits by halictid bees, bumble bees, and hoverflies. We suggest seed set of virgin flowers after single visits is a more reliable indicator of pollinator effectiveness than pollen deposition and would be a better indicator of pollinator effectiveness for future studies.

Developing and transitional countries undergoing rapid economic development will face growing problems with biological invasions because international commerce will bring new invaders. We assessed the potential for plant invasions in China by comparing the country's current invasive flora with that of the United States, a nation of similar size and latitudinal span but with a different history of plant introductions. Invasive plant species richness in the United States is about twice as high as it is in China. The remarkably lower fraction of invasive woody plants in China suggests that more alien trees and shrubs could invade Chinese habitats. Road density correlated with invasive plant species density among geographical units, with numbers for China lower than those for the United States. The data suggest that China has been invaded less than the United States has, and that the potential for new plant invasions in China is high. Measures toward preventing biological invasions are needed and timely teps taken now can prevent adverse impacts from future invasions.

China current invasive alien plant species were analyzed with regard to their floristic status, biological attributes and invasion status elsewhere. Most of the 270 species identified were annuals, followed by perennial herbs. Woody perennials made only about 10% of the species. The invasives were comprised of 59 families, the largest being Asteraceae, Poaceae, and Brassicaceae. The genera with most invasive species were Amaranthus , Ipomoea , and Solanum . Most of the species originated from the New World, notably from South America. About one-third of the species were serious invaders of natural habitats in countries other than China. The proportion of invasive alien plants in province floras ranged from 0.5 to 3.8%, absolute numbers from nine to 117 species per province. Density of invasive species was correlated positively with native species density at provincial scale. The results demonstrate that in China invasive plants are present throughout the country, with a particularly high species richness in the Southeast. The ecological diversity of invasive plants suggests wide ranging impacts which need to be assessed.

China is a vast country with rich biodiversity, which makes China especially vulnerable to invasive species. It has a long history of introduction of non-native species, especially those with perceived beneficial impacts. Its rapid economic development, including an explosive growth in international trade and transportation, has increased the potential for new introductions. Currently, alien species are widespread in the country, occur in many ecosystems, represent most major taxonomic groups, and are introduced unintentionally as well as intentionally for cultivation. The paper lists various cases of invasive species which have caused significant threats or damages to local natural or artificial ecosystems, and indicates that two example industries (fresh water fisheries and lawn grasses) have brought or tend to bring in many invasive species and hence have caused or will cause changes and loss of biodiversity in local ecosystems. Based on these studies, it is suggested that China combat the problem through enhancing awareness, development of a database on invasive species, strengthening international co-operation, preparing case studies and introducing the necessary legislation, regulations and monitoring.

该文报道了青藏高原一归化植物新纪录印加孔雀草(Tagetes minuta L．).

该文报道了青藏高原一归化植物新纪录印加孔雀草(Tagetes minuta L．).

菊科万寿菊属的印加孔雀草国内报道极少，只FloraofChina中记载，2006年台湾发现了归化的印加孔雀草。2011年，在北京郊区发现印加孔雀草野生群落，局部呈现生态危害。本文介绍了万寿菊属的属下分类和印加孔雀草的形态特征和生物学特性、地理分布、入侵性分析、危害、传入途径分析和控制等。

菊科万寿菊属的印加孔雀草国内报道极少，只FloraofChina中记载，2006年台湾发现了归化的印加孔雀草。2011年，在北京郊区发现印加孔雀草野生群落，局部呈现生态危害。本文介绍了万寿菊属的属下分类和印加孔雀草的形态特征和生物学特性、地理分布、入侵性分析、危害、传入途径分析和控制等。

全面整理了中国菊科植物外来种,确认迄今为止共计有74属148种(含亚种),并根据外来种的类型和用途进行了归类,分析了菊科外来入侵种的生物学特性,中国菊科外来种引种原因和途径及对我国生态系统的影响,为全面研究我国外来种、消除外来入侵种提供参考.

全面整理了中国菊科植物外来种,确认迄今为止共计有74属148种(含亚种),并根据外来种的类型和用途进行了归类,分析了菊科外来入侵种的生物学特性,中国菊科外来种引种原因和途径及对我国生态系统的影响,为全面研究我国外来种、消除外来入侵种提供参考.