Potential Distribution Of Invasive Species Pomacea Spp.in China And Population Genetic At Different Scales

Pomacea spp.are freshwater snails native to South and Central America,One of them,Pomacea canaliculata is one of the 100 worst invasive species in the world.At present,Pomacea canaliculata has invaded several countries in Europe,North America and Asia.This study collected the distribution data,the climate and altitude data,Maxent model was constructed to predict the potential distribution of Pomacea spp.,the diffusion speed of Pomacea spp.and the key environmental factors affecting it’s distribution were analyzed.Based on mtDNA COI and 16 S rRNA Gene fragments,the dispersal mode and invasion sources of P.canaliculata and P.maculata populations in Jiangxi Province were discussed,and the existing COI gene fragments were used to analyze the genetic diversity and genetic structure of P.canaliculata and P.maculata populations in different countries.The main results are as following:1.The potential distribution results showed that the potential distribution areas suitable for the survival of Pomacea spp.were mainly located in the southern of China,among which Zhejiang,Fujian,Jiangxi,Guangdong,Guangxi,Hainan and Taiwan had become a high distribution areas with serious damages.Although Shanghai,Hubei,Hunan,Sichuan,Guizhou,Tibet,Yunnan and Chongqing were in medium distribution,but with a high risk for outbreaks.2.The Maxent model showed that the influence of annual mean temperature was the most critical.At present,the diffusion rate of Pomacea spp.was about 7 km/year,the expansion process showed that the distribution of Pomacea spp.in southern China would continue to expand,and a comprehensive invasion pattern may be formed in the future with a tendency to further spread to the North.3.The investigation showed that 82 out of 131 sampling points had presence,involving 44 counties/districts in Jiangxi Province.The distribution pattern is widely distributed in the southnorth,and sporadically distributed in the north.Pomacea spp.were found in various habitat types,among which the static water(paddy fields,ponds and ditches)is relatively dense except reservoirs,while the fast-flowing waterwere scarce.4.The results of phylogenetic analysis based on haplotype showed that P.canaliculata and P.maculata were founded in Jiangxi Province,and P.canaliculata had a wider distribution range,presenting a Mosaic pattern with P.maculata.In addition,P.canaliculata is closely related to the Guangdong population,and P.maculata is closely related to the Sichuan population.The Guangdong population and the Sichuan population may be the source of introduction of Pomacea spp.in Jiangxi Province.Therefore,it is speculated that there may be multiple introduction events in Jiangxi Province.5.The results of haplotype network analysis showed that H2 haplotype was mostly shared in P.canaliculata,and H1 haplotype was primarily shared in P.maculata.The genetic distribution pattern of the same haplotype shared by different geographical populations hadn’t obvious correlation with river connectivity,the main diffusion mode of Pomacea spp.were carried by human activities.6.The results of AMOVA analysis showed that,the genetic variation within the population was greater than that between populations,indicating that P.canaliculata and P.maculata had significant genetic differentiation.The results of neutral test showed that Tajima’s and Fu’s of P.canaliculata and P.maculata didn’t reach significant levels,indicating that the population did not experience expansion.Similarly,there was multimodal from the mismatch distribution of analysis,and the results was consistent with the neutrality test.7.The genetic diversity and structure of P.canaliculata and P.maculata in global were analyzed,which published on GeneBank based on the COI gene sequence.The results showed that the genetic diversity of P.canaliculata population in 5 Southeast Asian countries(Mainland China,Philippines,Vietnam,Thailand and Korea)was higher than that the indigenous populations(Argentina),and there was a great difference in haplotypes types.In contrast,the genetic diversity of P.maculata population was lower than that of the indigenous populations(Brazil and Argentina),the number and types of haplotypes was much less than that of the indigenous populations.8.Haplotype network analysis results showed that P.canaliculata and P.maculata populations in non-native countries had unique haplotypes respectively.There was no frequent gene exchange,and their genetic geographical pedigree was relatively confused,indicating that each non-native country had different sources of invasion and introduction events.