Analysis On Genetic Diversity Of Velarifictorus Aspersus And Velarifictorus Micado

Velarifictorus aspersus and Velarifictorus micado are two sepcies of Orthoptera,Gryllidea,Velarifictorus,which inhabit among the wild ground, mound, tussock and rocks,burrowing or utilizing the existing gap of rubble.They are important agricultural pests which feed on stem,leaves,fruits,root of plants and prey on small insects.The study of genetic diversity of Velarifictorus aspersus and Velarifictorus micado has very important value in revealing cricket’s evolutionary mechanism, classification,identification and pest control.The two species of cricket are similar in individual form and studyng the genetic diversity by crickets’ form is prone to error.This article starts from the point of molecular biology,analysing the genetic diversity of Velarifictorus aspersus and Velarifictorus micado on16S rRNA,CO I,Cyt b partial genes of mitochondrial DNA.Results are listed as follows:(1) The length of Velarifictorus aspersus’s16S rRNA partial gene amplificated by PCR system is503bp. The average content of A,T,C,G are33.1%,36.0%,10.3%,20.6%for respectively,the content of A+T is69.1%.The length of Velarifictorus micadd’s16S rRNA partial gene is505bp.The average content of A,T,C,G are33.5%,35.2%,10.7%,20.6%for respectively,the content of A+T is68.7%.The length of Velarifictorus aspersus’s CO I partial gene is640bp.The average content of A,T,C,G are31.1%,38.4%,19.0%,11.5%for respectively, the content of A+T is69.5%.The length of Velarifictorus micado’s CO I partial gene is640bp.The average content of A,T,C,G are32.1%,35.9%,20.2%,11.8%for respectively, the content of A+T is68.0%.The length of Velarifictorus aspersus’s Cyt b partial gene is579bp. The average content of A,T,C,G are34.0%,34.8%,20.8%,10.4%for respectively, the content of A+T is68.8%.The length of Velarifictorus micado’s Cyt b partial gene is579bp.The average content of A,T,C,G are32.4%,36.2%,21.2%,10.2%for respectively, the content of A+T is 68.6%.The content of A+T on16S rRNA,CO Ⅰ,Cyt b partial genes of Velarifictorus aspersus and Velarifictorus micado is much more than C+G’s,there exists obvious A/T bias.(2) Obvious genetic diversity is found between Velarifictorus aspersus and Velarifictorus micado on16S rRNA partial gene.There are462conserved sites,43Variable sites,36parsimony information sites and7singleton sites.The similarity of sequences between Velarifictorus aspersus and Velarifictorus micado is about91.5%.The diversity of CO Ⅰ,Cyt b partial genes are more obvious than16S rRNA partial gene between Velarifictorus aspersus and Velarifictorus micado.CO Ⅰ partial gene has557conserved sites,83variable sites,72parsimony information sites and11singleton sites between the two species of cricket,the interspecific similarity of CO Ⅰ partial gene is87.0%.Cyt b partial gene has495conserved sites,84variable sites,59parsimony information sites and25singleton srtes,the interspecific similarity of Cyt b partial gene is85.5%.(3) To intraspecific genetic diversity,16S rRNA partial genes of Velarifictorus aspersus have1variable site, the intraspecific similarity of sequences is99.8%.16S rRNA partial genes of Velarifictorus micado have8variable sites,the intraspecific similarity of sequences is98.4%.CO I partial genes of Velarifictorus aspersus have633conserved sites,7variable sites,the intraspecific similarity of sequences is98.9%. CO Ⅰ partial genes of Velarifictorus micado have630conserved sites,10variable sites,the intraspecific similarity of sequences is98.4%.Cyt b partial genes of Velarifictorus aspersus have572conserved sites,7variable sites,the intraspecific similarity of sequences is98.8%.Cyt b partial genes of Velarifictorus micado have563conserved sites,16variable sites,the intraspecific similarity of sequences is97.2%.16S rRNA,CO Ⅰ and Cyt b partial genes all have high intraspecific sequence homology among different geographical populations of Velarifictorus aspersus and Velarifictorus micado.(4) This article also analyses the genetic distance of Velarifictorus aspersus and Velarifictorus micado based on Kimura-2model.The results display that:the average genetic distance of16S rRNA partial gene among the different geographical populations of Velarifictorus aspersus is0.002.The average genetic distance of Velarifictorus micado is0.011.The interspecific genetic distance between Velarifictorus aspersus and Velarifictorus micado is ranging from0.087to0.101,and the average is0.092.The average genetic distance of CO Ⅰ partial gene among the different geographical populations of Velarifictorus aspersus is0.011.The average genetic distance of Velarifictorus micado is0.011.The interspecific genetic distance of CO Ⅰ partial gene between Velarifictorus aspersus and Velarifictorus micado is ranging from0.137to0.148,and the average is0.141.The average genetic distance of Cyt b partial gene among the different geographical populations of Velarifictorus aspersus is0.013.The average genetic distance of Velarifictorus micado is0.016.The interspecific genetic distance of Cyt b partial gene between Velarifictorus aspersus and Velarifictorus micado is ranging from0.122to0.132,and the average is0.128.The genetic distance reflects that the intraspecific genetic diversity of16S rRNA,CO Ⅰ,Cyt b partial genes is very little among the different geographical populations of Velarifictorus aspersus and Velarifictorus micado,the degree of intraspecific genetic differentiation is very low. Meanwhile,the interspecific genetic diversity of these three kind of genes is obvious between Velarifictorus aspersus and Velarifictorus micado,much higher than intraspecific genetic diversity,which reflects that16S rRNA、CO Ⅰ、Cyt b partial genes are appropriate for analysis of genetic diversity between Velarifictorus aspersus and Velarifictorus micado,they can also act as molecular marker of classification and identification In addition,CO Ⅰ and Cyt b partial genes evolve faster than16S rRNA,and their intraspecific and interspecific genetic diversity are more obvious.(5)16S rRNA、CO Ⅰ、Cyt b partial genes are used as molecular marker to establish NJ phylogenetic tree,ME phylogenetic tree,ML phylogenetic tree and UPGMA phylogenetic tree of Velarifictorus aspersus and Velarifictorus micado.Analysis based on the phylogenetic trees reflect that the NJ phylogenetic tree,ME phylogenetic tree,ML phylogenetic tree and UPGMA phylogenetic tree which established by the same mitochondrial DNA are identical on topological structure:Velarifictorus micado of Bengbu geographical population firstly joins Velarifictorus micado of Dalian geographical population,then joins Velarifictorus micado of Taian geographical population; Velarifictorus aspersus of Zhanjiang geographical population joins Velarifictorus aspersus of Haikou geographical population,then gather together with the cluster of Velarifictorus micado.The outgroup become the single branch at last.The results from different phylogenetic trees are highly similar and obtain the support with high Bootstrap score.This also proves that the analysis of genetic diversity and genetic relationship between Velarifictorus aspersus and Velarifictorus micado is correct.