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Introduction Pathways (introduction + pathway)
Selected AbstractsFish movements: the introduction pathway for topmouth gudgeon Pseudorasbora parva and other non-native fishes in the UKAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 3 2010G. H. Copp Abstract 1.The contamination of fish consignments (for stocking or aquaculture) is a major pathway by which non-native organisms, including fish, are introduced to new areas. One of the best examples of this is the topmouth gudgeon Pseudorasbora parva, which was accidentally imported into Romania and then throughout Europe in consignments of Asian carp species. 2.The introduction and spread of topmouth gudgeon in the UK has been linked to imports and movements of the ornamental variety (golden orfe) of ide Leuciscus idus. To examine this hypothesis, relationships between authorized movements of both native and non-native fish species (in particular ide) and the occurrence in England of topmouth gudgeon were tested at the 10×10,km scale. 3.Topmouth gudgeon occurrence in the wild was significantly correlated with the trajectories of movements of ornamental fish species (ide/orfe, sunbleak Leucaspius delineatus) as well as a few non-ornamental fish species (European catfish Silurus glanis, Atlantic salmon Salmo salar and grass carp Ctenopharyngodon idella). 4.These results highlight the mechanism by which non-native fish species disperse from the point of first introduction, and especially that movements of fish within the country represent an important mechanism for accidental introductions of non-native species. © Crown copyright 2010. Reproduced with the permission of Her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [source] Inferring historical introduction pathways with mitochondrial DNA: the case of introduced Argentine ants (Linepithema humile) into New ZealandDIVERSITY AND DISTRIBUTIONS, Issue 5 2007Steve E. Corin ABSTRACT The threat imposed by invasive species and difficulties associated with control and management places more impetus on trying to prevent their introduction. The identification of introduction pathways is a vital component towards this goal. In this study, we use a genetic marker-based approach to retrospectively investigate the pathway of origin of the invasive Argentine ant (Linepithema humile) into New Zealand. We intensively sample the mitochondrial gene cytochrome b, from the entire known range of Argentine ants in New Zealand. No genetic variation was found in New Zealand. In order to identify likely introduction pathways, we use two alternative genetic analyses and suggest that a tcs approach that collapses identical haplotypes and calculates the probability of parsimony is superior to standard phylogenetic tree-building algorithms. A minimum spanning network allowed relationships to be examined among sequences collated from previous international studies. The cytochrome b sequence, when compared to a global database, matched that from an Australian population. That Australia is the potential source of Argentine ants is in agreement with the New Zealand interception record, as goods from Australia have the highest number of interception records of Argentine ants. Our approach can easily be duplicated for other organisms and the methodology can be more widely applied to help aid further efforts to identify the routes of transmission for other invasive species and allow us to efficiently direct our biosecurity monitoring effort. [source] Beyond control: wider implications for the management of biological invasionsJOURNAL OF APPLIED ECOLOGY, Issue 5 2006PHILIP E. HULME Summary 1Government departments, environmental managers and conservationists are all facing escalating pressure to address and resolve a diversity of invasive alien species (IAS) problems. Yet much research to date is primarily concerned with quantifying the scale of the problem rather than delivering robust solutions and has not adequately addressed all stages of the invasion process, and only a few studies embrace the ecosystem approach. 2Three successive steps, prevention, eradication and control, form the cornerstones of recommended best practices aimed at managing IAS. The goal of such actions is the restoration of ecosystems to preserve or re-establish native biodiversity and functions. 3Prevention is widely promoted as being a more environmentally desirable strategy than actions undertaken after IAS establishment, yet is hindered by the difficulty in separating invasive from non-invasive alien species. Furthermore, the high number of candidate IAS, the investment required in taxonomic support and inspection capacity, and the expense of individual risk assessments may act against the net benefits of prevention. More rewarding avenues may be found by pursuing neural networks to predict the potential composition of pest assemblages in different regions and/or model introduction pathways to identify likely invasion hubs. 4Rapid response should be consequent on early detection but, when IAS are rare, detection rates are compromised by low occurrence and limited power to discern significant changes in abundance. Power could be increased by developing composite indicators that track trends in a suite of IAS with similar life histories, shared pathways and/or habitat preferences. 5The assessment of management options will benefit from an ecosystem perspective that considers the manipulation of native competitors, consumers and mutualists, and reviews existing management practices as well as mitigates other environmental pressures. The ease with which an IAS can be targeted should not only address the direct management effects on population dynamics but also indirect effects on community diversity and structure. Where the goal is to safeguard native biodiversity, such activities should take into account the need to re-establish native species and/or restore ecosystem function in the previously affected area. 6Synthesis and applications. A comprehensive approach to IAS management should include consideration of the: (i) expected impacts; (ii) technical options available; (iii) ease with which the species can be targeted; (iv) risks associated with management; (v) likelihood of success; and (vi) extent of public concern and stakeholder interest. For each of these issues, in addition to targeting an individual species, the management of biological invasions must also incorporate an appreciation of other environmental pressures, the importance of landscape structure, and the role of existing management activities and restoration efforts. [source] Mitochondrial DNA reveals multiple Northern Hemisphere introductions of Caprella mutica (Crustacea, Amphipoda)MOLECULAR ECOLOGY, Issue 5 2008GAIL V. ASHTON Abstract Caprella mutica (Crustacea, Amphipoda) has been widely introduced to non-native regions in the last 40 years. Its native habitat is sub-boreal northeast Asia, but in the Northern Hemisphere, it is now found on both coasts of North America, and North Atlantic coastlines of Europe. Direct sequencing of mitochondrial DNA (cytochrome c oxidase subunit I gene) was used to compare genetic variation in native and non-native populations of C. mutica. These data were used to investigate the invasion history of C. mutica and to test potential source populations in Japan. High diversity (31 haplotypes from 49 individuals), but no phylogeographical structure, was identified in four populations in the putative native range. In contrast, non-native populations showed reduced genetic diversity (7 haplotypes from 249 individuals) and informative phylogeographical structure. Grouping of C. mutica populations into native, east Pacific, and Atlantic groups explained the most among-region variation (59%). This indicates independent introduction pathways for C. mutica to the Pacific and Atlantic coasts of North America. Two dominant haplotypes were identified in eastern and western Atlantic coastal populations, indicating several dispersal routes within the Atlantic. The analysis indicated that several introductions from multiple sources were likely to be responsible for the observed global distribution of C. mutica, but the pathways were least well defined among the Atlantic populations. The four sampled populations of C. mutica in Japan could not be identified as the direct source of the non-native populations examined in this study. The high diversity within the Japan populations indicates that the native range needs to be assessed at a far greater scale, both within and among populations, to accurately assess the source of the global spread of C. mutica. [source] The demography of introduction pathways, propagule pressure and occurrences of non-native freshwater fish in EnglandAQUATIC CONSERVATION: MARINE AND FRESHWATER ECOSYSTEMS, Issue 5 2010G. H. Copp Abstract 1.Biological invasion theory predicts that the introduction and establishment of non-native species is positively correlated with propagule pressure. Releases of pet and aquarium fishes to inland waters has a long history; however, few studies have examined the demographic basis of their importation and incidence in the wild. 2.For the 1500 grid squares (10×10,km) that make up England, data on human demographics (population density, numbers of pet shops, garden centres and fish farms), the numbers of non-native freshwater fishes (from consented licences) imported in those grid squares (i.e. propagule pressure), and the reported incidences (in a national database) of non-native fishes in the wild were used to examine spatial relationships between the occurrence of non-native fishes and the demographic factors associated with propagule pressure, as well as to test whether the demographic factors are statistically reliable predictors of the incidence of non-native fishes, and as such surrogate estimators of propagule pressure. 3.Principal coordinates of neighbour matrices analyses, used to generate spatially explicit models, and confirmatory factor analysis revealed that spatial distributions of non-native species in England were significantly related to human population density, garden centre density and fish farm density. Human population density and the number of fish imports were identified as the best predictors of propagule pressure. 4.Human population density is an effective surrogate estimator of non-native fish propagule pressure and can be used to predict likely areas of non-native fish introductions. In conjunction with fish movements, where available, human population densities can be used to support biological invasion monitoring programmes across Europe (and perhaps globally) and to inform management decisions as regards the prioritization of areas for the control of non-native fish introductions. © Crown copyright 2010. Reproduced with the permission of her Majesty's Stationery Office. Published by John Wiley & Sons, Ltd. [source] | ||||||||||