Molecular Phylogeny Of Tropidocephalini(Hemiptera:Delphacidae:Delphacinae) From China

The planthopper tribe Tropidocephalini(Hemiptera:Fulgoroidea:Delphacidae:Delphacinae)is the second largest group in the subfamily Delphacinae,more than 180 species in 37 genera have been described so far,distribute worldewide except Nearctic Region,among which 23 genera and 90 species are known in China.Most of the species in this tribe are bamboo feeders.Although classification research of tribe Tropidocephalini developed rapidly since it was established.However,the placement and status of some described genera need to be reconsidered,the phylogenetic relationship remain obscure.In the present thesis,the phylogenetic relationships among genera of the tribe Delphacini from China based on nuclear 28S rDNA and mitochondrial 16S rDNA,COXI and Cyt b partial genes were analyzed.The fragments of nuclear 28S rDNA and mitochondrial 16S rDNA,COXI and Cyt b partial genes of 43 representative species of 22 genera were amplified and sequenced.The aligned sequences are executed in MEGA5 to calculate the average content,variable sites,conserved sites,parsimony-informative sites and the ratio of transition and transversion(Ts/Tv).The pairwise distance obtains by using Kimura's 2-parameter model(K2-P).Maximum parsimony,maximum likelihood and Bayesian analyses are chosen to reconstruct the phylogeny based on the single gene 28S rDNA,16S rDNA,COXI,Cyt b the combined genes 28S rDNA + 16S rDNA,28S rDNA + COXI,28S rDNA +Cyt b,16S rDNA + COXI and 28S rDNA + 16S rDNA + COXI,28S rDNA + COXI + Cyt b respectively.The results are as follows:1.The result of sequence variation analyses showed the sequences of 28S rDNA from the tribe Tropidocephalini was 728bp in length,including 164 variable sites,559 conservative sites and 131 parsimony-informative sites,and the percentage of A + T was 47.5%;16S rDNA was 489bp in length,including 255 variable sites,232 conservative sites and 200 parsimony-informative sites,and the percentage of A + T was 78.4%;COXI was 516bp in length,including 224 var:iable sites,292 conservative sites and 193 parsimony-informative sites,and the percentage of A + T was 70.0%;Cyt b was 613bp in length,including 328 variable sites,285 conservative sites and 297 parsimony-informative sites,and the percentage of A + T was 73.7%;The average content of A+T is much higher than the content of C + G in mitochondrial genes.This strong A + T bias in nucleotide frequencies is similar to that of other insects.2.The analysis based on Kimura's 2-parameter model(K2-P)obtained the pairwise distances.The smallest genetic distance of 28S rDNA between outgroup and ingroup is 0.030,and the largest is 0.141;The smallest genetic distance between ingroups is 0.000,and the largest is 0.114;The smallest genetic distance of 16S rDNA between outgroup and ingroup is 0.132,and the largest is 0.229;The smallest genetic distance between ingroups is 0.012,and the largest is 0.238;The smallest genetic distance of COXI between outgroup and ingroup is 0.154,and the largest is 0.273;The smallest genetic distance between ingroups is 0.000,and the largest is 0.268;The smallest genetic distance of Cyt b between outgroup and ingroup is 0.236,and the largest is 0.389;The smallest genetic distance between ingroups is 0.000,and the largest is 0.233.3.The MP,ML and BI trees of representative species in the tribeTropidocephalini based respectively on 28S rDNA,16S rDNA,COXI,Cyt b,28S rDNA + 16S rDNA,28S rDNA + COXI,28S rDNA + Cyt b,16S rDNA + COXI ? 8S rDNA + COXI+ 16S rDNA,28S rDNA + COXI + Cyt b were reconstructed,and the resulting phylogeny indicated that:(1)Representative species of genus Tropidocephala formed a clade which shows the genus Tropidocephala is a monophyletic group.(2)Three representative species of genus Malaxella formed a clade which shows the genus Malaxella is a monophyletic group.(3)Representative species of genus Epeurysa formed a clade which shows the genus Epeurysa is a monophyletic group.(4)Representative species of genus Purohita formed a clade which shows the genus Purohita is a monophyletic group.(5)The genera Malaxa and Lauriana constitute a sister group.(6)Anchia stenoprocessa and Paranectopia lasaensis form a clade,which suggest that the generda Anchia and Paranectopia have closer relationship.(7)The genus Bambusiphaga was not form a clade,but the monophyly examination of Bambusiphaga suggest that the genus Bambusiphaga is a monophyletic group.