黑、吉、辽、蒙归化植物分布格局及其影响因素

为了解黑、吉、辽、蒙归化植物分布格局及其驱动因素,本研究基于实地调查和资料收集,对黑、吉、辽、蒙4省(区) 48个地级市(盟)归化植物物种组成及时空分布进行了分析。结果表明:当前四省(区)共有归化植物70科239属370种,菊科、禾本科和豆科最多,约七成为人为有意引入,欧洲是最大原产地。不同地级城市归化植物多样性差异较大,整体呈东高西低趋势,省内存在"强省会"现象。沈阳、哈尔滨、呼和浩特等省会城市及大连等沿海发达城市归化植物分布较多。通辽市、松原市和鄂尔多斯市等平原或草原地区分布较少。GDP、土地利用程度和年均气温是造成该分布格局的主要因素。Logistic拟合显示,目前黑、吉、辽、蒙归化植物种数已趋于稳定,但随着"东北振兴",四省(区)经济必将出现新局面,归化植物累积速度很可能加快,相关部门仍需保持警惕。     

Native and naturalized range size in Pinus: relative importance of biogeography,introduction effort and species traits

Aim Pine trees (genus Pinus) represent an ancient lineage, naturally occurring almost exclusively in the Northern Hemisphere, but introduced and widely naturalized in both hemispheres. As large trees of interest to forestry, they attract much attention and their distribution is well documented in both indigenous and naturalized ranges. This creates an opportunity to analyse the relationship between indigenous and naturalized range sizes in the context of different levels of human usage, biological traits and the characteristics of the environments of origin. Location Global. Methods We combined and expanded pre‐existing data sets for pine species distributions and pine species traits, and used a variety of regression techniques (including generalized additive models and zero‐inflated Poisson models) to assess which variables explained naturalized and indigenous range sizes. Results Indigenous and naturalized range sizes are positively correlated but there are many notable exceptions. Some species have large indigenous ranges but small or no naturalized ranges, whereas others have small indigenous ranges, but have naturalized in many regions. Indigenous range is correlated to factors such as seed size (?), age at first reproduction (?), and latitude (+, supporting Rapoport's rule), but also to the extent of coverage of species in the forestry literature (+). Naturalized range size is strongly influenced by the extent of coverage of species in the forestry literature (+), a proxy for propagule pressure. Naturalization was also influenced by average elevation in the indigenous range (?) and age at first reproduction (?). Main conclusions The macroecological and evolutionary pressures facing plant groups are not directly transferable between indigenous and naturalized ranges. In particular, there are strong biases in species naturalization and expansion in invasive ranges that are unrelated to factors determining indigenous range size. At least for Pinus, a new set of macroecological patterns are emerging which are profoundly influenced by humans.     

Integrating species distribution models and interacting particle systems to predict the spread of an invasive alien plant

Aim We demonstrate how to integrate two widely used tools for modelling the spread of invasive plants, and compare the performance of the combined model with that of its individual components using the recent range dynamics of the invasive annual weed Ambrosia artemisiifolia L. Location Austria. Methods Species distribution models, which deliver habitat‐based information on potential distributions, and interacting particle systems, which simulate spatio‐temporal range dynamics as dependent on neighbourhood configurations, were combined into a common framework. We then used the combined model to simulate the invasion of A. artemisiifolia in Austria between 1990 and 2005. For comparison, simulations were also performed with models that accounted only for habitat suitability or neighbourhood configurations. The fit of the three models to the data was assessed by likelihood ratio tests, and simulated invasion patterns were evaluated against observed ones in terms of predictive discrimination ability (area under the receiver operating characteristic curve, AUC) and spatial autocorrelation (Moran’s I). Results The combined model fitted the data significantly better than the single‐component alternatives. Simulations relying solely on parameterized spread kernels performed worst in terms of both AUC and spatial pattern formation. Simulations based only on habitat information correctly predicted infestation of susceptible areas but reproduced the autocorrelated patterns of A. artemisiifolia expansion less adequately than did the integrated model. Main conclusions Our integrated modelling approach offers a flexible tool for forecasts of spatio‐temporal invasion patterns from landscape to regional scales. As a further advantage, scenarios of environmental change can be incorporated consistently by appropriately updating habitat suitability layers. Given the susceptibility of many alien plants, including A. artemisiifolia, to both land use and climate changes, taking such scenarios into account will increasingly become relevant for the design of proactive management strategies.     

Molecular genetic approaches to elucidate the ecological and evolutionary issues associated with biological invasions

Biological invasions may cause serious damage to the native environments and threaten the native biodiversity. Molecular genetic approaches have been found to be powerful tools for investigating the ecological and evolutionary aspects of biological invasions because the genetic structure and level of genetic variation of an invasive species are changed following its invasion. The present article reviews the use of molecular markers in addressing various aspects of invasive species. The application of these techniques has shown that many invasive species are actually "cryptic" species – species whose uniqueness is only recognizable at the genetic level. An estimation of the actual number of invasive species is essential when evaluating its ecological and economic impacts. Molecular genetic approaches have also enabled the source populations of invasive species to be identified. Reconstructions of invasion histories are crucial to preventing future invasions and conserving the native biodiversity, while comparisons of genetic variations between the native and introduced populations provide valuable opportunities to elucidate the mechanisms of rapid adaptation demonstrated by many invasive species.     

外来种入侵的过程、机理和预测

生物入侵是指某种生物从原来的分布区域扩展到一个新的（通常也是遥远的）地区,在新的区域里,其后代可以繁殖、扩散并持续维持下去,生物入侵成功的原因,即与入侵者本身的生物学,生态学特征有关,也与群落的脆弱性有关,入侵者可能较本地种的竞争能力强,更适应当地的环境,有的入侵者还可以改变环境,使之对已有利,而不利于本地种。缺乏天敌制约。群落的稳定性低和异常的环境扰动往往导致生物入侵,生物入侵的预测包括哪一种外来种会变成入侵种？哪些生态系统区域会被入侵？影响程度如何？入侵种的扩散态势如何等内容,对有关的理论和模型作了评介。     

On interacting populations that disperse to avoid crowding: The effect of a sedentary colony

An analysis is given of a model for two interacting species, one mobile and the other sedentary, in which the mobile one disperses to avoid crowding. The spatial distribution of the mobile species over the habitat, as it evolves with time, is studied. In particular it is shown that a colony of the sedentary species can form an effective barrier against the spreading mobile species, and prevent it from entering certain parts of the habitat.     

Concerning invasive species: Reply to Brown and Sax

Abstract Biological invasions have commonly occurred, and to a lesser degree continue to do so, without human assistance. It is, however, a combination of the rate and magnitude, as well as the distances and agency involved, that separates human‐driven invasion processes from self‐perpetuated colonization events. Exotic species are a pervasive and major component of human‐induced global change. Decisions to manage invasive species will require judgements to be communicated from scientists to policy makers, because scientists may often be the only ones in the position to make them.     

Tolerance to drought and flooding events provides a competitive advantage for an invasive over a native plant species

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物种多样性和功能群多样性与生态系统生产力的关系——以内蒙古短花针茅草原为例

生物多样性与生态系统生产力之间的关系是当前生态学领域的热点问题。短花针茅(Stipa breviflora)草原是内蒙古荒漠草原的主要类型, 生态系统脆弱, 气候波动剧烈, 研究内蒙古短花针茅草原生物多样性与生产力的关系具有十分重要的意义。该研究在内蒙古短花针茅草原区设置了202个样地进行群落调查, 在干旱区及半干旱区两种资源供给下, 分析了物种丰富度、功能群丰富度与生产力的关系, 旨在解决两个科学问题: 1)物种多样性和功能群多样性中, 哪一种与生产力关系更为密切?2)资源供给对多样性和生产力关系的影响。结果表明: 1)物种丰富度、群落生产力与年降水量呈正相关关系, 而功能群丰富度与年降水量之间不存在显著相关性; 2)群落生产力随物种丰富度的增加而增加, 且两者间呈正线性关系, 功能群丰富度与生产力之间不存在显著相关关系; 3)资源供给会影响多样性与生产力之间的关系, 资源供给低时, 多样性对生产力贡献较低, 资源供给高时, 多样性对生产力的贡献较高。该研究丰富了多样性与生产力关系的研究, 同时, 考虑到植物功能性状的研究在近几年受到生态学家的重视, 且多数研究集中于小尺度的人工控制实验, 因此, 在大尺度自然生态系统中开展功能性状多样性与生态系统功能关系的研究将十分必要。     

Non‐native fishes and climate change: predicting species responses to warming temperatures in a temperate region

1. Temperate regions with fish communities dominated by cold‐water species (physiological optima <20 °C) are vulnerable to the effects of warming temperatures caused by climate change, including displacement by non‐native cool‐water (physiological optima 20–28 °C) and warm‐water fishes (physiological optima >28 °C) that are able to establish and invade as the thermal constraints on the expression of their life history traits diminish. 2. England and Wales is a temperate region into which at least 38 freshwater fishes have been introduced, although 14 of these are no longer present. Of the remaining 24 species, some have persisted but failed to establish, some have established populations without becoming invasive and some have become invasive. The aim of the study was to predict the responses of these 24 non‐native fishes to the warming temperatures of England and Wales predicted under climate change in 2050. 3. The predictive use of climate‐matching models and an air and water temperature regression model suggested that there are six non‐native fishes currently persistent but not established in England and Wales whose establishment and subsequent invasion would benefit substantially from the predicted warming temperatures. These included the common carp Cyprinus carpio and European catfish Silurus glanis, fishes that also exert a relatively high propagule pressure through stocking to support angling and whose spatial distribution is currently increasing significantly, including in open systems. 4. The potential ecological impacts of the combined effects of warming temperatures, current spatial distribution and propagule pressure on the establishment and invasion of C. carpio and S. glanis were assessed. The ecological consequences of C. carpio invasion were assessed as potentially severe in England and Wales, with impacts likely to relate to habitat destruction, macrophyte loss and increased water turbidity. However, evidence of ecological impacts of S. glanis elsewhere in their introduced range was less clear and so their potential impacts in England and Wales remain uncertain.     

Seasonal and habitat variations in diet of the invasive driftwood catfish Trachelyopterus galeatus in a Neotropical river basin,Brazil

The characteristics of successful invaders often include generalist traits that enable adaptation to new environments through plastic responses, including their diet. The use of trophic resources of invasive driftwood catfish Trachelyopterus galeatus of the Upper Paraná River basin, Brazil, were studied with diet analysis and stable isotopic niche metrics based on δ¹⁵N and δ¹³C to test differences between a free-from-dam and damming population, and between wet and dry season. Stomach content analyses revealed significant differences between the populations. The diet of the riverine free-flowing river population was macroinvertebrate dominated, with Coleoptera and Lepidoptera prominent. In the damming population, diet was largely plant based, although Coleoptera was also prominent. Trophic niche breadth comparisons revealed a larger niche in the free-from-dam population versus the damming population that was independent of season. In both sites had dietary differences between the wet and dry season according to stomach contents analyses, although these were less prominent according to stable isotope metrics. Therefore, the diet of this invader is relatively general and plastic, enabling their exploitation of the varying availability of food resources between free-from-dam and damming river sections, and between wet and dry season.     

Seed arrival, ecological filters, and plant species richness: a meta-analysis

Theoretical models predict that effects of dispersal on local biodiversity are influenced by the size and composition of the species pool, as well as ecological filters that limit local species membership. We tested these predictions by conducting a meta-analysis of 28 studies encompassing 62 experiments examining effects of propagule supply (seed arrival) on plant species richness under contrasting intensities of ecological filters (owing to disturbance and resource availability). Seed arrival increased local species richness in a wide range of communities (forest, grassland, montane, savanna, wetland), resulting in a positive mean effect size across experiments. Mean effect size was 70% higher in disturbed relative to undisturbed communities, suggesting that disturbance increases recruitment opportunities for immigrating species. In contrast, effect size was not significantly influenced by nutrient or water availability. Among seed-addition experiments, effect size was positively correlated with species and functional diversity within the pool of added seeds (species evenness and seed-size diversity), primarily in disturbed communities. Our analysis provides experimental support for the general hypothesis that species pools and local environmental heterogeneity interactively structure plant communities. We highlight empirical gaps that can be addressed by future experiments and discuss implications for community assembly, species coexistence, and the maintenance of biodiversity.     

Ancestral origins and invasion pathways in a globally invasive bird correlate with climate and influences from bird trade

Invasive species present a major threat to global biodiversity. Understanding genetic patterns and evolutionary processes that reinforce successful establishment is paramount for elucidating mechanisms underlying biological invasions. Among birds, the ring‐necked parakeet (Psittacula krameri) is one of the most successful invasive species, established in over 35 countries. However, little is known about the evolutionary genetic origins of this species and what population genetic signatures tell us about patterns of invasion. We reveal the ancestral origins of populations across the invasive range and explore the potential influence of climate and propagule pressure from the pet trade on observed genetic patterns. Ring‐necked parakeet samples representing the ancestral native range (n = 96) were collected from museum specimens, and modern samples from the invasive range (n = 855) were gathered from across Europe, Mauritius and Seychelles, and sequenced for two mitochondrial DNA markers comprising 868 bp of cytochrome b and control region, and genotyped at 10 microsatellite loci. Invasive populations comprise birds that originate predominantly from Pakistan and northern areas of India. Haplotypes associated with more northerly distribution limits in the ancestral native range were more prevalent in invasive populations in Europe, and the predominance of Asian haplotypes in Europe is consistent with the higher number of Asian birds transported by the pet trade outside the native range. Successful establishment of invasive species is likely to be underpinned by a combination of environmental and anthropogenic influences.     

Competition between tree seedlings and herbaceous vegetation: support for a theory of resource supply and demand

1 We measured competition intensity (CI) between herbaceous vegetation and tree seedlings ( Quercus macrocarpa and Q. ellipsoidalis ) along an experimental moisture–light gradient. Contrasting theories were tested by comparing variation in competition intensity to changes in neighbour biomass and resource supply and demand.
2 CI based on survival was inversely correlated with net soil water supply (gross supply minus demand by herbaceous vegetation). CI was not positively correlated with either gross resource supply or neighbour biomass, contrary to predictions of Grime's triangular model for plant strategies.
3 Many of the inconsistencies and conflicting results that have characterized the recent literature on plant competition could be eliminated if changes in competition intensity along a resource gradient are compared with changes in net resource supply rather than changes in productivity or neighbour biomass.
4 Tree seedling success in savannas and grasslands may be strongly influenced by the intensity of competition from herbaceous vegetation. Factors that reduce soil water content are likely to increase competition intensity (and reduce seedling success) in these environments, while factors that increase soil water content will favour seedling success through decreased competition for water with herbaceous vegetation.     

Unusually high‐quality soil seed banks in a Midwestern U.S. oak savanna region: variation with land use history,habitat restoration,and soil properties

An overarching conclusion in the literature is that soil seed banks rarely contain many restoration‐target species and are often liabilities rather than assets to restoration. Our objective was to evaluate composition and spatial variation of seed banks and their potential contributions to restoration, including restoration‐target species such as rare species and those characterizing historical habitats. On 64 sites in a Midwestern U.S. oak savanna landscape, we sampled soil seed banks in seven habitat types (restored oak savannas, oak woodlands, and mesic prairies; unmanaged upland oak and mesic forests; and unmanaged and managed pine plantations). The germinable seed bank was exceptionally rich in restoration‐target species. In total for the 64 sites, seedlings of 127 species emerged from seed bank samples. Of the 101 native species, 56 were restoration‐target species, an unusually high number among seed bank studies. Restoration‐target species in seed banks included 13 threatened or endangered species, in addition to 43 other specialist species associated with high‐quality native habitats or on a floral list thought to characterize historical ecosystems. When analyzed across the 64‐site gradient, seed banks differed among the seven habitat types and varied with historical (1939) land use, recent management activities that restored open‐structured habitats, and biophysical gradients of tree density, soil drainage, and soil texture. While not all restoration‐target species were detected in the seed bank, the unusually high‐quality seed bank is a potential asset to restoration and was partly structured along environmental gradients across the landscape.     

Inter-strain competition and dispersal in aphids: evidence from a greenhouse study

1. Crops are often colonised by aphids having different life-history traits, and the aphids and their offspring compete for the shared resource. The intraspecific competition and dispersal characteristics of two strains (A and B) of the cotton aphid Aphis gossypii on cucumber were examined in a greenhouse study. Strain A normally feeds on cucumber, whereas strain B originated from melon but develops on cucumber. Both strains reproduce exclusively via parthenogenesis and can be discriminated using molecular markers. 2. The strains were released at the same time on different plants in a greenhouse. Total density and their dispersion within and between plants were recorded through time, and the frequency of each strain was assessed using DNA fingerprinting. The Lotka–Volterra competition model was used to test for inter-strain competition and to estimate its intensity. 3. Strain A had the highest rate of increase and carrying capacity, and became the most frequent strain, nearly displacing strain B. Strain B was the most common only on the plants it infested first. The competition was unbalanced as strain B was affected strongly by strain A, but strain A was only affected minimally by strain B. This asymmetrical relationship for strain B was not due only to competition for the shared resource. 4. Such competition may in part explain the reduction of genetic polymorphism observed by others in the field where colonising strains coming from different hosts compete and some are eliminated. Polymorphism in A. gossypii populations in nature is thought to be maintained by heterogeneous patches of hosts differentially favourable for different clones.     

Inferring the origin of populations introduced from a genetically structured native range by approximate Bayesian computation: case study of the invasive ladybird Harmonia axyridis

Correct identification of the source population of an invasive species is a prerequisite for testing hypotheses concerning the factors responsible for biological invasions. The native area of invasive species may be large, poorly known and/or genetically structured. Because the actual source population may not have been sampled, studies based on molecular markers may generate incorrect conclusions about the origin of introduced populations. In this study, we characterized the genetic structure of the invasive ladybird Harmonia axyridis in its native area using various population genetic statistics and methods. We found that native area of H. axyridis most probably consisted of two geographically distinct genetic clusters located in eastern and western Asia. We then performed approximate Bayesian computation (ABC) analyses on controlled simulated microsatellite data sets to evaluate (i) the risk of selecting incorrect introduction scenarios, including admixture between sources, when the populations of the native area are genetically structured and sampling is incomplete and (ii) the ability of ABC analysis to minimize such risks by explicitly including unsampled populations in the scenarios compared. Finally, we performed additional ABC analyses on real microsatellite data sets to retrace the origin of biocontrol and invasive populations of H. axyridis, taking into account the possibility that the structured native area may have been incompletely sampled. We found that the invasive population in eastern North America, which has served as the bridgehead for worldwide invasion by H. axyridis, was probably formed by an admixture between the eastern and western native clusters. This admixture may have facilitated adaptation of the bridgehead population.     

A novel interference behaviour: invasive wasps remove ants from resources and drop them from a height

This study reports a novel form of interference behaviour between the invasive wasp Vespula vulgaris and the New Zealand native ant Prolasius advenus. By videotaping interactions at bait stations, we found that wasps commonly remove ant competitors from food resources by picking up the workers in their mandibles, flying backward and dropping them unharmed some distance from the food. Both the frequency and the efficiency of the wasp behaviour significantly increased with the abundance of ant competitors. Ant removals were the most common interference events initiated by wasps when ants were numerous, while intraspecific conflicts among wasps were prominent when few ants were present. The 'ant-dropping' behaviour emphasizes how asymmetry in body sizes between competitors can lead to a pronounced form of interference, related to asymmetric locomotion modes.