The Genetic Diversity And Breeding System Of Reticulitermes Flaviceps

The genetic diversity and the breeding system of Reticulitermes flaviceps colonies in Shannxi and Sichuan provinces detected based on SSR and mitochondrial DNA markers.The results are as follows:?1?The genetic diversity of 22 colonies of R.flaviceps in Shannxi and Sichuan was analyzed by using six pairs of microsatellite primers.The number of alleles Na of 105 individuals in 7colonies in Shannxi ranged from 2.429 to 3.000,and the average number of alleles was2.738±0.132.The effective allele number Ne is in the range of 1.832-2.293,the average effective allele is 2.057±0.094,and the observed heterozygosity Ho ranges from 0.390 to0.610,the average value is 0.494±0.037.The expected heterozygosity He ranges from0.420-0.537,the average is 0.472±0.024,Shannon's information index I is 0.773±0.044,and the range is between 0.690 and 0.890.The polymorphic information content PIC minimum value is 0.460,the maximum value is 0.812,and the average value is 0.638±0.050,which is greater than 0.5.Therefore,these 6 microsatellite primers are highly polymorphic to the colony in Shannxi.There were 225 individuals in 15 colonies in Sichuan.The number of alleles ranged from 1.933 to 3.600,with an average of 2.889±0.130.The number of effective alleles was 1.589-2.544,the mean was 2.107±0.095,and the observed heterozygosity ranged from 0.347 to 0.622 with an average of 0.512±0.038.The expected heterozygosity range is between 0.286 and 0.514 and the average expected heterozygosity is 0.436±0.025.Shannon's information index had a maximum value of 0.938,a minimum value of 0.448,and an average value of 0.752-0.046.The polymorphic information content PIC minimum value is 0.627,the maximum value is 0.897,and the average value is 0.777±0.039,which is also greater than 0.5.Therefore,these 6 microsatellite primers are also highly polymorphic to the Sichuan's colonies.The genetic diversity of termites in the two places was similar.The number of effective alleles and the average number of effective alleles were lower than the number of alleles and the average number of alleles,indicating that the alleles were unevenly distributed in the colonies.The expected heterozygosity is greater than 0.3,combined with Shannon's information index I,it can be considered that the termite colonies in these two places have moderately high genetic diversity.?2?By analyzing the F statistics and the gene flow Nm of 330 individuals in 22 colonies.The F_IS value was-0.133±0.058,indicating that heterozygotes were abundant in the termite colonies,which was consistent with that the expected heterozygosity He was lower than the observed heterozygosity Ho in all colonies.The genetic differentiation coefficient F_ST ranges from 0.405 to 0.483,with an average of 0.450±0.014 and more significant than 0.15.The gene flow index Nm is 0.309±0.018,ranging from 0.267 to 0.368,and the value is less than 1.Both of these indicate the lack of genetic communication between different colonies,leading to the emergence of genetic differentiation.The Bayesian clustering method of software structure2.2 shows that the seven nests in Shannxi have similar genetic structure,and there are obvious differences in the genetic structure of termite nests in Sichuan.However,among the15 colonies in Sichuan,the three colonies collected from Wenjiang,Dujiangyan and Qingchengshan have similar genetic structures with the Shannxi colonies.?3?In the analysis of the breeding system of the termites,it is found that seven colonies in Shannxi belong to the extended families,while twelve colonies in Sichuan belong to the simple families and only three colonies belong to the extended families.The phenomenon of colony fusion has not been found.This may be because the extened families are all collected from the natural environment,which is less damaged by human.The habitat is suitable for the survival of termites,thus allowing the expansion of the colonies.The 12 simple families in Sichuan are collected from the urban area.On the one hand,human activities will affect the survival of termites.On the other hand,the urban structure is mostly hard cement concrete,which is not conducive to the expansion of termite nests.?4?Marking by using mitochondrial DNA COII,the R.flaviceps in Shaanxi and Sichuan were sequenced and analyzed,get the size of about 701 bp COII gene fragment.The contents of bases A,T,C and G were 39.3%,24.4%,22.1%and 14.2%,respectively.The content of A+T was 63.7%higher than that of G+C?36.3%?,which was consistent with the obvious AT bias of insect mitochondria.useing the software DNAsp5.0,we analyzed 14 haplotypes in the R.flaviceps colonies in Shannxi and Sichuan,numbered H1 to H14.?5?The genetic diversity of the R.flaviceps in Shanxni and Sichuan was analyzed by software DNAsp5.0,and the genetic variation in the colony was more.The results of mismatch distributions and neutrality tests show that the actual observation curve is consistent with the expected curve and shows a multi-peak distribution trend.The value of Tajima'sD is equal to0.3073,and the result is not significant?p>0.1?.It is indicated that the population of R.flaviceps conforms to the neutral theory,and the group has no pouplation expansion in recent time and is in equilibrium.The fixed coefficient F_ST value of the colony was calculated by molecular variation?AMOVA?analysis.The fixed coefficient of the nest group was 0.89,indicating that the colony directly caused a certain level of genetic differentiation due to lack of gene flow.The AMOVA results of the mitochondrial COII gene in different geographical nests of the R.flaviceps showed that the genetic variation among the population?89.34%?was significantly greater than the genetic variation within the population?10.66%?.