Phylogenetic Status And Genetic Diversity Of Cheyletus Malaccensis Oudemans

In this paper,the phylogenetic status was studied by method of cladistics and the genetic diversity of Cheyletus malaccensis Oudemans populations was evaluated by using ISSR molecular marker.Moreover,the genetic structure and gene flow were also analyzed and discussed.The paper mainly involves the following two aspects.1 Phylogenetic status of C.malaccensisBased on the morphological characters,the phylogeny trees of the subfamily Cheyletinae and the genus Cheyletus were constructed.The results showed that the genus Cheyletus,which C.malaccensis belongs to,was initially separated from the subfamily Cheyletinae and formed a single clade.Thus Cheyletus was proved to be the most original fauna in this subfamily;The Mp tree and Nj tree of Cheyletus almost possessed the same top structures,which indicated that the statuses of all species in the genus were confirmed except for C.schneideri.The two cheyletids C. trouessarti and C.trux firstly diverged from Cheyletus.C.malaccensis was one of the latest evolved species,and formed a sibling group with high bootstrap value,which suggested that they owned a close phylogentic relationship.2 Analysis to genetic diversity of C.malaccensis populations(1) Optimization of ISSR-PCR reaction system:the optimal amplification system was established with orthogonal design.2.5μL 10×PCR buffer,2 L MgCl₂,0.1μL Taq DNA polymerase,0.5μL dNTPs,1μL primers,4μL template DNA and 14.9μL ddH₂O.(2) Amplification results:thirteen primers,which produced legible,stable and high polymorphic bands,had been selected to amplify the genome DNA of 5 sampled populations(GD,AH,JS,NC and JJ).Total 71 bands were yielded,65 of which were polymorphic bands.The percentage of polymorphic bands(PPB) was 91.55%.(3) Analysis to genetic diversity:the evaluation of population genetic diversity, which was executed by the percentage of polymorphie bands(PPB),Shannon information index(â… ) and expected heterozygosity(H_e) respectively,provided the same conclusion that the levels of the genetic diversity could be ordered in abundance as NC＞GD＞JJ＞JS＞AH.At the species level,the number of alleles per locus N_a= 1.9155±0.2801,the effective number of alleles per locus N_e=1.5515±0.3402,and the values of PPB,â… and H_e were 91.55%,0.3423 and 0.5138,respectively.(4) Genetic structure and gene flow:the value of G_st, the coefficient of gene differentiation was 0.4021,indicating a high level of genetic differentiation among populations.And the result was consistent with AMOVA analysis.Dendrogram constructed using the UPMGA method and Nei's unbias genetic distance displayed the relationships between the 5 sampled populations as(NC GD)(JJ(JS AH)).NC and GD had a close relationship while the other 3 populations were close to each other,indicating that the populations of C.malaccensis strongly differentiated between Nanchang and Jiujiang.The level of gene flow(Nm=0.3717) was low between populations.Besides,the Mantel test showed that there was no significant correlation between the genetic distance and geographic distance(r=0.3720,P＜0.001),which suggested that the gene flow between different populations was not restricted by the geographic distance.