| The Phascolosoma is an important genus in the Sipuncula,and the P.esculenta,also known as the P.arcuatum,it is the special specie of Sipuncula in China.They are also the two main species of Sipuncula in China.In order to understand the genetic distribution and genetic diversity of the Phascolosoma population in the Beibu Gulf area and the genetic population of the natural population of Phascolosoma,this article was conducted in Beihai,Guangxi,Fangchenggang,Guangxi,from October 2017 to February 2018.The exploration and collection of the resources of the genus Pleurotus in the Beibu Gulf region,such as Zhanjiang in Guangdong,Sibi in Hainan and Hai Phong in Vietnam,were discovered.A total of three species were found,their names are P.esculenta,P.scolops and P.pucificum.The morphology and habitat of the three species of Phascolosoma are quite different.China's leopard caterpillars are mainly P.esculenta and P.scolops.P.pucificum are collected from Haiphong City,Vietnam.Through survey and analysis,we have a certain understanding of the distribution and density of the Phascolosoma in the Beihai,and based on the COI gene and the 16S rRNA gene,we sequenced the Phascolosoma in the Beibu Gulf region,and used DNAstar,Dna Sp5.0,and MEGA 7.0.The gene sequence software analyzes the sequence.The results show:(1)There are two species of Phascolosoma on the Beihai Peninsula,one is P.esculenta and the other is P.scolops.The morphology of the two species of Phascolosoma is quite different.The size of the P.esculenta is relatively large,ranging from 50-110mm.There are a large number of brown papillae on the body surface.The color of the mastoids at the base of the kiss and at the end of the body is darkened.Closely arranged,with prominent longitudinal muscle bundles;the size of the P.scolops is between 25-45mm,the body is brownish yellow,translucent,and the longitudinal muscle bundles are not obvious.The samples of P.pucificum were collected from Haiphong City,Vietnam,with the largest body size,ranging from 60-120mm.The longitudinal muscle bundles were obvious and the body wall was thicker.The distribution area of the Phascolosoma in the Beihai Peninsula mainly includes the mangrove areas in the southeast of the peninsula such as the Jinhai Bay Wetland Park,Xicun Port,and Yintan Bridge.The distribution density of P.esculenta is between 6.24-7.28 ind/m2.The biomass was 11.48-14.13g/m2,and the tidal flat near No.1 Beibu Gulf also had the distribution of Phascolosoma.It was P.scolops with a density of 28.8ind/m2 and a biomass of 17.86g/m2.The density was significantly greater than that of P.esculenta,and the biomass index was not much different.(2)Through the sequencing analysis of COI gene and 16S rRNA gene,the genetic bases,parsimony-informative sites,genetic distance determination,NJ-tree construction,and MP-tree analysis of the three Phascolosoma species in the Beibu Gulf area were shown.The base content of the three species of Phascolosoma was not significantly different.The content of A+T was greater than that of C+G.Using different methods of stalk formation,the final results showed that the P.esculenta and P.pucificum were closely related to each other.The relationship is closer,and the P.scolops relationship between the burrowing worms is more distant,and the morphological results are consistent with the morphological classification.(3)Base pairs of COI sequences of different populations of P.esculenta,among which the difference in base content of different populations is not significant,the A base content of the four local populations is between 29.77-30.1%,and the G content is Between 16.34 16.5%,the T content was between 29.13-29.77%and the C content was between 24.11-24.43%.The A+T content was significantly greater than the C+G content,and the sum of the A+T content was located at 59.22-59.55 The sum of C+G content is between 40.45-40.78%.In line with the characteristics of the mitochondrial genes of the cyst nematode.Among the 80 individuals,a total of 47 haplotypes were detected,of which Hap30 haplotypes were distributed in all four populations,with 12 individuals,accounting for 15%of the population.The remaining haplotypes were randomly distributed in different communities.among.Based on the Kimura-biparametric model,the genetic distances between the different populations and within the population were calculated.The results showed that the genetic distance within the population was 0.0013-0.0028,and the maximum genetic distance between the populations was 0.0021,the smallest 'genetic distance.At 0.0032,there is an overlap between genetic distances between groups and groups,and the genetic distance is at the same level.The results of molecular variance analysis(AMOVA)showed that the genetic variation among populations was 1.71%and the genetic variation within the population was 98.29%,indicating that the population genetic variation was mainly from within the population rather than between groups.Based on the Kimura-biparametric model,the adjacency tree was constructed for different groups.The results showed that there were no clear haplogroups among the 47 haplotypes,and most of their nodes were below 60,showing no regionality.There is geographical isolation The population of P.esculenta experienced a population expansion event. |
PDF Full Text Request