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Successful Invasion (successful + invasion)
Selected AbstractsThe role of enemy release, tolerance and resistance in plant invasions: linking damage to performanceECOLOGY LETTERS, Issue 8 2010Young Jin Chun Ecology Letters (2010) 13: 937,946 Abstract An explanation for successful invasion is that invasive alien species sustain less pressure from natural enemies than co-occurring native species. Using meta-analysis, we examined whether invasive species: (1) incur less damage, (2) exhibit better performance in the presence of enemies, and (3) tolerate damage more than native species. Invasive alien species did not incur less damage than native species overall. The performance of invasive alien species was reduced compared to natives in the presence of enemies, indicating the invasive alien species were less tolerant to damage than native species. However, there was no overall difference in performance of invasive alien and native species with enemies present. The damage and degree of reduction in performance of invasive alien relative to native species did not depend on relatedness to natives. Our results suggest aliens may not always experience enemy release, and enemy release may not always result in greater plant performance. [source] Evidence for a combination of pre-adapted traits and rapid adaptive change in the invasive plant Centaurea stoebeJOURNAL OF ECOLOGY, Issue 4 2010Martin L. Henery Summary 1. Introduced plants have the potential to rapidly evolve traits of ecological importance that may add to their innate potential to become invasive. During invasions, selection may favour genotypes that are already pre-adapted to conditions in the new habitat and, over time, alter the characteristics of subsequent generations. 2. Spotted knapweed (Centaurea stoebe) occurs in two predominantly spatially separated cytotypes in its native range (Europe,Western Asia), but currently only the tetraploid form has been confirmed in the introduced range (North America), where it is invasive. We used several common garden experiments to examine, across multiple populations, whether tetraploids and diploids from the native range differ in life cycle, leaf traits and reproductive capacity and if such differences would explain the predominance of tetraploids and their advance into new habitats in the introduced range. We also compared the same traits in tetraploids from the native and introduced range to determine whether any rapid adaptive changes had occurred since introduction that may have enhanced invasive potential of the species in North America. 3. We found tetraploids had lower specific leaf area, less lamina dissection and fewer, narrower leaves than diploids. Diploids exhibited a monocarpic life cycle and produced few if any accessory rosettes. Diploids produced significantly more seeds per capitulum and had more capitula per plant than tetraploids. In contrast, the vast majority of European tetraploids continued to flower in both seasons by regenerating from multiple secondary rosettes, demonstrating a predominantly polycarpic life cycle. 4. During early growth tetraploids from North America achieved greater biomass than both tetraploids and diploids from the native range but this did not manifest as larger above-ground biomass at maturity. In North American tetraploids there was also evidence of a shift towards a more strictly polycarpic life cycle, less leaf dissection, greater carbon investment per leaf, and greater seed production per capitulum. 5.,Synthesis. Our results suggest that the characteristics of tetraploid C. stoebe pre-adapted them (compared to diploid conspecifics) for spread and persistence of the species into habitats in North America characterized by a more continental climate. After the species' introduction, small but potentially important shifts in tetraploid biology have occurred that may have contributed significantly to successful invasion. [source] Role of sexual reproduction in the spread of an invasive clonal plant Solidago canadensis revealed using intersimple sequence repeat markersPLANT SPECIES BIOLOGY, Issue 1 2006MEI DONG Abstract Invasive species, second only to habitat loss as a cause of biodiversity loss, pose serious threats to native biodiversity and ecosystems. Little is known about the mechanisms that some exotic plants use to become invasive in their non-native ranges. Solidago canadensis, native to North America, was intentionally introduced to many countries where it has become an invasive plant. To understand the roles that reproductive mode plays in successful invasion of exotic plants, and the relative importance of sexual reproduction and clonal growth, the genetic diversity and clonal structure of two S. canadensis populations from Shanghai, China were investigated using intersimple sequence repeats. Samples were collected in a grid pattern with intervals of 2 m among adjacent individuals within the studied area (approximately 30 m × 30 m) for each population. Results showed that the percentages of polymorphic loci for the two populations were 97.9% and 96.5% and clonal diversity measured using the Simpson Diversity Index was 1.00 for both populations. No identical genotypes were found among the analyzed samples. It is suggested from this study that sexual reproduction facilitates the establishment of new S. canadensis populations, whereas clonal expansion maintains and enlarges the established populations. Thus, limiting sexual reproduction of S. canadensis may effectively control the invasion of this species. [source] Invasion by Rattus rattus into native coastal forests of south-eastern Australia: are native small mammals at risk?AUSTRAL ECOLOGY, Issue 4 2009VICKI L. STOKES Abstract The black rat, Rattus rattus, is an alien rodent in Australian ecosystems where niche overlap with native small mammals may lead to competition for resources and displacement of native species. In coastal habitats surrounding Jervis Bay in south-eastern Australia, R. rattus co-occurs with the native bush rat, Rattus fuscipes, and brown antechinus, Antechinus stuartii. Relative distributions and abundances, and fine-scale space use suggest invasive and native rodents compete for use of space and habitat. Such competitive interactions were not evident between R. rattus and native A. stuartii, which was negatively influenced more by disturbance to habitat. Differences in rodent communities between spatially separate forests forming the northern and southern peninsulas of Jervis Bay potentially reflect symmetrical competition and differences in competitive outcomes. In southern forests, R. rattus was largely restricted to patches of disturbed forest associated with campgrounds. Competitive interference by native rodent populations inhabiting surrounding intact forests may have so far limited R. rattus colonization of these areas. In northern forests, R. rattus was the predominant rodent irrespective of disturbance, while populations of R. fuscipes were unusually low seemingly due to poor juvenile recruitment. Native individuals avoided areas frequented by adult R. rattus and given that species did not partition use of microhabitats, R. rattus most likely precluded R. fuscipes from suitable habitat and in doing so limited native populations. We discuss how natural disturbance of habitat and human activity have potentially facilitated successful invasion by R. rattus of the northern forests. Studies that manipulate rodent populations are required to support these interpretations of observed patterns. [source] Automated classification of Plasmodium sporozoite movement patterns reveals a shift towards productive motility during salivary gland infectionBIOTECHNOLOGY JOURNAL, Issue 6 2009Stephan Hegge Abstract The invasive stages of malaria and other apicomplexan parasites use a unique motility machinery based on actin, myosin and a number of parasite-specific proteins to invade host cells and tissues. The crucial importance of this motility machinery at several stages of the life cycle of these parasites makes the individual components potential drug targets. The different stages of the malaria parasite exhibit strikingly diverse movement patterns, likely reflecting the varied needs to achieve successful invasion. Here, we describe a Tool for Automated Sporozoite Tracking (ToAST) that allows the rapid simultaneous analysis of several hundred motile Plasmodium sporozoites, the stage of the malaria parasite transmitted by the mosquito. ToAST reliably categorizes different modes of sporozoite movement and can be used for both tracking changes in movement patterns and comparing overall movement parameters, such as average speed or the persistence of sporozoites undergoing a certain type of movement. This allows the comparison of potentially small differences between distinct parasite populations and will enable screening of drug libraries to find inhibitors of sporozoite motility. Using ToAST, we find that isolated sporozoites change their movement patterns towards productive motility during the first week after infection of mosquito salivary glands. [source] | ||||||||||