2, sea level rise and eutrophication on the process of biological invasion have been analyzed based on the invasive status of coastal ecosystem. The results indicate that elevated CO2 disturbs the competitive balance between invasive and native species. Sea level rise adjusts the spatial pattern of invasive species and eutrophication of coastal ecosystem promotes further spread of alien species. At last, the research hotspots about interactions between global change and biological invasion in coastal ecosystem are discussed.]]>

Corythucha ciliata (Say) (Hemiptera: Tingidae), was first found in Changsha of Hunan Province in 2002 and has since been recorded in 25 cities in 11 Chinese provinces or municipalities. This species feeds mainly on leaves of Platanus spp. trees. Heavy infestations have been concentrated in the Yangtze River basin. Here, we briefly describe this species, focusing on its invasion biology. In so doing, we first review the lace bug’s biological characteristics, including its life history, feeding habits and reproduction, and then focus on its invasion ecology, covering invasion pathways, adaptation during invasion (cold and heat tolerance), and major environmental factors affecting its invasion success and its impact on native urban ecosystems. Finally, we make some suggestions for managing this bug in Chinese cities.]]>

The impacts of invasive alien species on the genetic diversity and evolutionary responses of native species are poorly understood. Accumulating evidence shows that invasive plant species can lead to genetic erosion of natives directly through hybridization and gene infiltration, or even affect genetic diversity of natives through creation of new “genotypes”. Exotic species can also alter genetic diversity of natives indirectly through habitat fragmentation and modification, processes which influence gene flow within and among populations and result in inbreeding and genetic drift. On the other hand, some studies show that native species can respond evolutionarily to invasive plants, thereby reducing or eliminating invasive impacts. While interacting with invasive species, native species in both above- and below-ground ecosystems exhibit a series of evolutionary events such as adaptation, speciation or extinction. To more comprehensively evaluate the ecological impacts of biological invasions and the adaptive potential of natives, here we review the impacts of invasive plants on biological (genetic) diversity of native species, and the evolutionary responses of natives. We also discuss relationships between the genetic and evolutionary responses of natives and the success of invasive plants, and propose topics for further research.

Spartina alterniflora have rapidly displaced native Phragmites australis on China’s East Coast. In the Yangtze Estuary’s Jiuduansha wetlands, nitrogen content in aerial standing litter for both Spartina and Phragmites was measured from November 2003 to April 2004. Spartina had larger nitrogen content (N g/m2) in aerial litter than Phragmites. Nitrogen content in aerial litter of Spartina sheathes and stems increased during our study period; this trend was not observed for Phragmites. In January 2006, new (produced in winter of 2005) and old (produced in winter of 2004) Spartina aerial sheath and stem litter was collected from six sites on China’s East Coast. Aerial litter of old sheathes and stems had higher nitrogen concentrations than new sheathes and stems, suggesting that the increase of nitrogen content in Spartina sheath and stem aerial litter was consistent across sites. Further greenhouse experiments showed that the increase of nitrogen content in Spartina aerial litter was associated with microbial epiphytic nitrogen fixation. Our results suggest that Spartina invasion alters aerial litter nitrogen dynamics, which might increase nitrogen input into invaded ecosystems and facilitate rapid expansion of Spartina into additional habitats.]]>

Understanding the functional traits and ecological mechanisms associated with successful invasions of alien plants is a key role of the field of invasion ecology. Through literature review and analysis of plant functional traits contributing to successful plant invasions and the demands for functional traits at different invasion stages, we discuss the relationships between the functional traits and invasiveness of alien plants as well as related ecological mechanisms. Functional traits that have been studied in relation to their invasions mainly include seed characters, and morphological, developmental, physiological, clonal and propagation characteristics, as well as genetic variation and plasticity of phenotype. The impacts of these functional traits on invasion success vary from one stage to another. At the introduction stage, plant invasions are mainly affected by seed characters. At the establishment stage, stress-tolerance related physiology and propagation traits exert important influences. At the explosion stage, clonal characters and physiological traits related to competitive ability largely contribute to invasion success. Because plant invasions result from interactions between plant functional traits and environmental features, further studies on plant invasions should consider both the effects of invasion stage and specific environmental variables on invasion success.

Biological invasions have caused tremendous ecological and socio-economic damages worldwide. Therefore, it is important to develop methods for their effective management. Biological invasion is a process of adaptive evolution in which hybridization and introgression play an important role in promoting invasive species by changing their invasiveness. Therefore, understanding how the genetic mechanisms of hybridization and introgression influence biological invasion will facilitate effective control of invasive species. The escape of transgenes with special functions into populations of wild relatives through hybridization and introgression may change the invasiveness and weediness of the wild relatives, causing undesired environmental problems. This paper introduces the role of hybridization and introgression in adaptive evolution and speciation, and discusses how an alien species can change its adaptability, competitive ability, and invasiveness in new habitats through introgressive hybridization. Hybridization and introgression can cause polyploid and homoploid evolution of plant species, thereby influencing the fitness of new species and promoting the formation of an invasive species in new habitats. At the same time, with the rapid development of transgenic technologies, transgenic crops are being extensively released into the environment for commercial production. Biological invasion is a complicated evolutionary and ecological process, and future research should investigate the roles of hybridization and introgression in biological invasions in the context of the myriad factors that influence the process.

Interactions between vector insects, plant viruses and host plants are complex and diverse. Although much work has been done to study the tripartite relationships, their roles in biological invasions have been rarely explored. The limited case studies available indicate that the interactions may be mediated by the host plant susceptibility to viruses, the suitability of host plants to vector insects, and the insects’ capacity to utilize host plants. When a host plant is highly susceptible to the virus but shows a low level of suitability to the insect, and the insect has a strong capacity to use different host plants, an indirect mutualistic relationship is likely to occur between vector insect and plant virus via their shared host plants. This kind of mutualism can contribute to the widespread invasion of vector insects as well as the epidemics of plant viruses. In view of the significance of the tripartite interactions in biological invasions, future effort should be made to investigate comparatively many more combinations of different species, and various technologies can be used to reveal the physiological and molecular mechanisms of the interactions.

The regions invaded by alien species are normally disjunct from their native ranges, so it is difficult to understand the reasons for successful invasion through studies conducted only in native or invasive ranges. Many researchers have engaged in whole-range studies of invasive species, i.e. studying the exotics both in their introduced and native ranges, in order to explain the present geographical patterns and invasion mechanisms of alien plants. Here, we review progress in whole-range studies on invasive plants by summarizing their main contents, achievements and significance. We also point out the problems and shortcomings of existing studies and provide prospects for further studies. There are two main approaches in whole-range studies: (1) comparison of phenotypic traits (e.g. growth, reproduction, and ecophysiology) between invasive and native populations through direct observation and common garden experiments; (2) genetic diversity analysis and phylogeographic research using molecular markers. Such studies have tested major hypotheses of plant invasion mechanisms, and provided advice for management and control of invasive plants. However, the methods and contents of existing whole-range studies are imperfect, and further improvements based on increased international cooperation are needed.

Alternanthera philoxeroides), a worldwide noxious weed, has caused enormous ecological and economic losses in China. To better understand the species’ successful invasion, and to predict relationships between expansion of its population and environmental conditions, we compared morphological traits of alligator weed with two closely related species, i.e. the geographically restricted alien A. pungens and the native A. sessilis, under different water and nutrient conditions in a common garden experiment. Compared to A. pungens and A. sessilis, alligator weed produced more biomass with high availability of water and nutrients, but did not in conditions of low water availability. These results suggest that the invasiveness of alligator weed may be influenced by environmental conditions. In addition, alligator weed had marginally greater specific leaf area (SLA) and phenotypic plasticity than its congeners. Phenotypic plasticity and SLA may thus have predictive value for invasiveness of alien species under multiple environmental conditions.]]>