| Biological invasion is the process by which organisms are transported,either naturally or artificially,from their native living habitat to other new ecological settings.The development,reproduction,and spread of invasive species in new habitats not only undermine the biodiversity and stability of the ecosystem,but also have the potential to disrupt society and the economy,pose a threat to human health,and even lead to ecological disasters.The global increase in trade and socioeconomic growth has led to a significant escalation in the severity of biological invasions worldwide.Biological invasions are a global economic and ecological challenge and have emerged as one leading cause of the rapid decline in global biodiversity.Biological invasions have resulted in significant ecological disasters and inflicted harm on invading areas.Therefore,it is important for the effective prevention and control of invasive species that timely monitoring,early warning,and emergency treatment during the introduction or spread of invasive species.Object:In this study,we used environmental DNA techniques in combination with species distribution models to perform early monitoring of exotic amphibian species in areas of active socio-economic development in China,and the comprehensive results were then validated through field surveys.Our objective is to assess the reliability and potential of combining environmental DNA technology with species distribution modeling as an early monitoring tool for exotic species.The ultimate goal is to provide timely advice for early prevention and control,scientific management planning for the exotic amphibian species,and new programs for early monitoring.Methods:Initially,the exotic amphibian species with the highest likelihood of being distributed in the study area were identified through database surveys,literature reviews,and market visits.Next,species distribution models were used to predict the potential distribution areas of these identified species and evaluate the risk of invasion.Subsequently,the results of the species distribution model and environmental DNA assay were combined and analyzed to produce a composite result of early monitoring.Finally,we used field surveys to validate the composite results of early monitoring.Results:First,through database surveys,literature reviews,and market visits,a total of four exotic amphibian species most likely to be distributed in the wild in Shenzhen(Hoplobatrachus rugulosus,Eleutherodactylus planirostris,Rana catesbeiana,and Xenopus laevis).Second,the species distribution models showed that the Hoplobatrachus rugulosus(0.9991 ± 0.0002)and Eleutherodactylus planirostris(0.7987 ± 0.0175)had a high risk of establishment,while the Rana catesbeiana(0.1799 ± 0.0049)and Xenopus laevis(0.1303 ±0.0021)had a low risk of establishment.Then,the results of the species distribution model combined with the environmental DNA technique detection showed that the results of environmental DNA detection for the exotic species Hoplobatrachus rugulosus(high establishment risk species)and Eleutherodactylus planirostris(high establishment risk species)are highly reliable,while the results for Rana catesbeiana(low establishment risk species)needed further verification.Subsequent field investigations also indicated that the environmental DNA testing results for Hoplobatrachus rugulosus and Eleutherodactylus planirostris were highly reliable,as both species were observed in the field and evidence of their establishment was obtained.However,no evidence of Rana catesbeiana was found in the field investigation.Our study conclusively shows that environmental DNA combined with species distribution models for early monitoring of exotic species has great promise for application.Conclusion:The combination of environmental DNA and species distribution models for the early monitoring of invasive species is reliable and has great potential for monitoring most exotic species in the early stages. |
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