A Comparative Study Of Genetic Diversity Of Tapinoma Melanocephalum In Mainland And Island Populations From South China

Tapinoma melanocephalum(Hymenoptera,Formicidae,Dolichadernae)is a ubiquitous household and agricultural pest.T.melanocephalum is mainly distributed in tropic or subtropics area,even can spread to temperate zone because of commercial activities or human interference factors.It threats theecosystem of invadedplace and human health.In this study,with microsatellite marker method and mitochorial DNA gene sequence(mt DNA),populations and colonies genetic diversity of six mainland areasand five island areasof South Chinawere estimated and the effect of geographic isolation on the difference of population genetic diversityor genetic divergence of the ghost ant were unrarved.The results providedtheoreticalfoundation for controlling spread and potential damage of this species.The main results were described as following:1 Screening ten microsatellite loci in T.melanocephalumBy sequencing partial information using 454 GS FLX+ sequencing technology of next-generation sequencing(NGS),we isolated the microsatellite loci of T.melanocephalum.After polymorphism testing,we have successfully screened 10 pair primers with stable amplification and medium or high level of polymorphism,which provided an efficient tool for studying population genetic diversity on T.Melanocephalum.2 A comparative study of effect of geographic isolation on population genetic diversity of T.melanocephalumIn this study,we analyzed genetic diversity of T.melanocephalum from different geographic populationsusing the aboved six polymorphism primers(loci).The result of Hardy-Weinberg equilibriumtesting showed thatfour of six microsatellite loci significantly deviated Hardy-Weinberg equilibrium(P<0.05).There was higher null allele frequency.We deleted the loci 364 to avoid affecting the result estimated by null allele.We got 128 alleles among 11 geographic population by five microsatellite primers amplified,the allele richness ranged from 7.600 to 14.664 in each loci,the average observed heterozygosity and expected heterozygosity were 0.460 and 0.663,respectively.Population genetic diversity of mainland in South China of T.melanocephalum showed no significant difference compared with island populationsby t-test.In colony level,colonies from SCD island indicated low genetic diversity,but there was no significant difference compared with other colonies.In population level,the genetic diversity of SCD island population was significant lower than partial continent population with lower expected heterozygosity in SCD population.Based on 610 bp sequence fragment of mitochondrial COI gene sequence,7 haploid types were generated.Mainlandand island populationsin South China showed lower or medium degree haplotype diversity,which was similar with the consequence of each population by SSR molecular marked analysis.3 Comparative study of effect of geographic isolation on population genetic structure of T.melanocephalumThe result by Beyasy structure analysis showed that most of the colonies between mainland and island populationswere mixed together and had no relationship with the geographic sites of the colonies.Population genetic differentiation demonstrated that mainland and island populationsin South China had a low level genetic differentiation.SCD island population showed medium or higher degree genetic differentiation paired with other mainland and island populations in South China except SJ population(FST> 0.05).There was no significant correlation for both paired colony genetic distance and geographic distance through Mantel testing.Geographic isolation is not enough to limit gene flow.The result of AMOVA showed that the genetic variation from mainland and island population in South China was originated from individual within colonies.When analyzing the relatedness with all individuals,the individuals from SCD island colonies displayed a higher relatedness than other colonies.It will promote this island population to become a supercolony with lower diversity and higher genetic divergence compaired with other population.BO TTLENECK testing indicated that some populations have experienced bottleneck,such as SJ,ZJ,MZ,WZD and DAD population.That was in relatively stable state among 11 geographic populations by neutrality test,the value of Tajima's D and Fu's Fs were-0.072 and-0.250,resepectively,which were not significant deviated from 0.It also suggested that all population were a relatively stable state combing with mismatch distribution analysis.