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Intentional Introduction (intentional + introduction)
Selected AbstractsInvasion success: does size really matter?ECOLOGY LETTERS, Issue 2 2002A. W. Miller The recent paper by Roy et al. (2001) presents a compelling relationship between range limit shifts, climatic fluctuations, and body size for marine bivalves in the fossil record. However, their extension of body size as a correlate for contemporary marine bivalve introductions is problematic and requires further scrutiny. Unlike their analysis of the fossil assemblage, the approach used for contemporary invasions does not adequately control for dispersal mechanism (vector) or source region. First, their analysis included mariculture species, intentionally introduced because of their large size, creating a vector-specific bias. Second, successful invaders from multiple source regions (Northern Hemisphere) were compared with potential invaders from a single source region (north-eastern Pacific), leaving both source and vector as uncontrolled variables. We present an analysis of body size for bivalve introductions from a single vector and source region, indicating no correlation between body size and invasion success when eliminating intentional introduction, source region and transport vector as confounding factors. [source] The fate of an intentional introduction of Formica lugubris to North America from EuropeJOURNAL OF APPLIED ENTOMOLOGY, Issue 4 2008A. J. Storer Abstract Red wood ants (Formica s.str.) are not prevalent in the forests of North America, but commonly occur in conifer and mixed conifer forests in northern Europe and Asia. In 1971, a European red wood ant species, Formica lugubris, was intentionally established in a 35-year-old predominantly mixed conifer plantation approximately 30 km north of QC, Canada. The purpose of its introduction was to evaluate the potential of this species as a biological control agent against conifer-defoliating Lepidoptera species. This red wood ant introduction was monitored periodically for about 5 years after establishment, but its long-term fate has not been reported. We visited this field site in 2005 and found that this species was well established, and we could locate some of the nests that resulted from the original release. We mapped and measured over 100 nests around the site of original release, which ranged from 5 cm in height to over 1 m. We estimated the population of introduced ants to have grown to over 8 million in the last 34 years. Significant clustering of nests suggests that these nests may be one supercolony. F. lugubris has become a dominant understory arthropod in this mixed forest, and is likely to have ecological impacts, including effects at the community and ecosystem level. [source] A review of changes in the fish assemblages of Levantine inland and marine ecosystems following the introduction of non-native fishesJOURNAL OF APPLIED ICHTHYOLOGY, Issue 4 2005M. Goren Summary The arrival of non-native fishes in the Levant Basin began in the late 19th century. Whereas the presence of most of the 40 non-native freshwater fishes stem from intentional introductions, either for aquaculture or pest control, the 62 species of non-native marine fishes arrived by natural dispersal via the Suez Canal. Of the non-native freshwater species, five have established successful breeding populations (mosquitofish Gambusia affinis, common carp Cyprinus carpio, crucian carp Carassius carassius, swordtail Xiphophorus hellerii and rainbow trout Oncorhynchus mykiss), and seven are regularly stocked in natural habitats (thinlip mullet Liza ramada, flathead mullet Mugil cephalus, European eel Anguilla anguilla, grass carp Ctenopharyngodon idella, Asian silver carp Hypophthalmichthys molitrix, bighead carp Aristichthys nobilis, black carp Mylopharyngodon piceus). Some non-native species appear to have out-competed native species. Gambusia affinis may have caused the extirpation of two native cyprinid fishes from the Qishon River basin (Levant silver carp Hemigrammocapoeta nana and common garra Garra rufa) and the southern Dead Sea (endemic Sodom's garra G. ghoerensis). The opening of the Suez Canal in 1869 allowed entry into the eastern Mediterranean of Indo-Pacific and Erythrean biota, with the latter now dominating the community structure (50,90% of fish biomass) and function (altered native food web) of the Levantine littoral and infra-littoral zones. The process has accelerated in recent years concurrent with a warming trend of the seawater. Record numbers of newly discovered non-native species is leading to the creation of a human-assisted Erythrean biotic province in the eastern Mediterranean. [source] Plant invasions , the role of mutualismsBIOLOGICAL REVIEWS, Issue 1 2000DAVID M. RICHARDSON ABSTRACT Many introduced plant species rely on mutualisms in their new habitats to overcome barriers to establishment and to become naturalized and, in some cases, invasive. Mutualisms involving animalmediated pollination and seed dispersal, and symbioses between plant roots and microbiota often facilitate invasions. The spread of many alien plants, particularly woody ones, depends on pollinator mutualisms. Most alien plants are well served by generalist pollinators (insects and birds), and pollinator limitation does not appear to be a major barrier for the spread of introduced plants (special conditions relating to Ficus and orchids are described). Seeds of many of the most notorious plant invaders are dispersed by animals, mainly birds and mammals. Our review supports the view that tightly coevolved, plant-vertebrate seed dispersal systems are extremely rare. Vertebrate-dispersed plants are generally not limited reproductively by the lack of dispersers. Most mycorrhizal plants form associations with arbuscular mycorrhizal fungi which, because of their low specificity, do not seem to play a major role in facilitating or hindering plant invasions (except possibly on remote islands such as the Galapagos which are poor in arbuscular mycorrhizal fungi). The lack of symbionts has, however, been a major barrier for many ectomycorrhizal plants, notably for Pinus spp. in parts of the southern hemisphere. The roles of nitrogen-fixing associations between legumes and rhizobia and between actinorhizal plants and Frankia spp. in promoting or hindering invasions have been virtually ignored in the invasions literature. Symbionts required to induce nitrogen fixation in many plants are extremely widespread, but intentional introductions of symbionts have altered the invasibility of many, if not most, systems. Some of the world's worst invasive alien species only invaded after the introduction of symbionts. Mutualisms in the new environment sometimes re-unite the same species that form partnerships in the native range of the plant. Very often, however, different species are involved, emphasizing the diffuse nature of many (most) mutualisms. Mutualisms in new habitats usually duplicate functions or strategies that exist in the natural range of the plant. Occasionally, mutualisms forge totally novel combinations, with profound implications for the behaviour of the introduced plant in the new environment (examples are seed dispersal mutualisms involving wind-dispersed pines and cockatoos in Australia; and mycorrhizal associations involving plant roots and fungi). Many ecosystems are becoming more susceptible to invasion by introduced plants because: (a) they contain an increasing array of potential mutualistic partners (e.g. generalist frugivores and pollinators, mycorrhizal fungi with wide host ranges, rhizobia strains with infectivity across genera); and (b) conditions conducive for the establishment of various alienalien synergisms are becoming more abundant. Incorporating perspectives on mutualisms in screening protocols will improve (but not perfect) our ability to predict whether a given plant species could invade a particular habitat. [source] | ||||||||||