Effects Of Island Isolation On Genetic Diversity Of The Tephritid Fruit Fly Bactrocera Dorsalis

Geographical isolation is a key factor to limit the species spread and affect the genetic diversity, which plays an important roll in the genetic diversity of winged insects.The samples we collected were from 12 mainland, including Guangzhou, Zhuhai,Zhanjiang, Taishan, Yunfu of Guangdong province; Beihai, Nanning, Zhongshan of Guangxi province; Mengzi of Yunnan province; Zhangzhou of Fujian and Ningnan of Sichuan, as well as from Waidingling island, Dongao island, Naozhou island and Weizhou island of six islands population. We adopted the morphological genetic marker and 8microsatellite loci and mt DNA CO? of molecular genetic marker analysis, to study the genetic structure and genetic differentiation of Bactrocera dorsalis on island and mainland population and to explore the island isolation affected flies genetic structure or differentiation. The results showed as follows:1) The results of morphological marker genetic differences between populations showed that wing area and vein had significant smaller on island population than mainland among the morphology index of B.dorsalis. There was no significance on vein angle. In additional, three horizontal length of arteries and veins among the morphology indexes had positive correlation with wing area. And the different latitude had no significant effect on the body size of B.dorsalis population.2) The results of mitochondrial CO ? molecular marker showed that we found 163 haplotypes in total by testing 337 items CO? sequences of B.dorsalis. The sharing haplotypes were 38, Haplotype type figure general showed starlike distribution network,which suggested that B.dorsalis underwent the population expansion. As a whole,among 18 flies population showed the higher level diversity in nucleotide(0.00706) and haplotype(0.9674±0.0055).Moreover, the results demonstrated that there were the lower genetic differentiation on island populations and mainland populations. The individual variation among populations caused population overall mutation using F-statistics measured the differentiation degree of inter-population.3) The results of microsatellite markers suggested that we tested overall 122 allele using 8microsatellite premiers. The observed heterozygosity(HO), expected heterozygosity(HE),Nei's and Percentage of polymorphic loci of four mainland populations are same with six island populations,which were 0.3321, 0.7008, 0.6833 and 100%, respectively.Number of observed allele NA, effective number of alleles NE, Shannon 's of Mainland populations were 6.344, 3.6838 and1.4271, Six island populations were 3.8755,1.4587 and 0.3321.It was also showed that six island populations and 4 mainland populations had the higher genetic diversity. The AMOVA analysis displayed that the genetic variation between populations was very low and originated from individuals.Geographic population distance had no correlation with genetic distance.