Study On The Genetic Pattern And Its Factors Of Ficus Tikoua Population

Genetic structure reveals the spatial distribution of genetic diversity,it also indicates how the genetic variation within population or among populations distribute across different time and space.It is associated to the evolutionary process and reflects how species respond to environment change and determines the potential adaptation ability of a species to environment change.In this study,we explored the genetic structure of 58 Ficus tikoua's natural populations in Southeast China by using chloroplast gene and nuclear gene?microsatellites?.At the same time,we simulated the potential distribution of F.tikoua during the last interglacial?LIG?and the last glacial maximum?LGM?using bioclimatic data,associated the morphological divergence of F.tikoua,discussing the reason caused genetic structure.The results are as follows:?1?281 specimens from 57 populations were randomly selected to sequence using three chloroplast genes?rps12-rpL20,trnS-trnG,psbM-trnD?.In total,19 haplotypes were found in combined cpDNA gene fragments with low genetic diversity(?=0.55×10^-3).The genetic differentiation index G_ST?0.751?is significant larger than N_ST?0.863?,indicating significant phylogeographic pattern is existed in F.tikoua's population.The results of AMOVA revealed that most genetic variation happened among populations?84.67%?.A significant population differentiation was found in F.tikoua(?_ST=0.847).?2?High level of genetic diversity was shown in the nSSR dataset in F.tikoua population?H_E=0.618?.Cluster analysis assigned two genetic groups of 58 populations?1378 individuals?of F.tikoua,which are Sichuan Basin group?SC?and Yungui Plateau group?YG?.A significant genetic differentiation(F_ST=0.178,P<0.001)was found in the populations of F.tikoua and the genetic distance is increasing as the geographic distance increasing.The results of AMOVA indicated most genetic variation came from within populations?81.42%?.A significant genetic differentiation was also detected between Yungui Plateau and Sichuan Basin?P<0.001?.?3?The genetic structure of F.tikoua is similar with the geographic pattern of male flowers distribution in F.tikoua,showing the divergence between south and north populations,which was distributed at Yungui Plateau and Sichuan Basin region,respectively.Gene flow?Nm?equals 1.154 indirectly calculated by F_ST.A significant negative relationship between genetic distance and geographic distance across whole populations and within each genetic group,indicating limited gene flow may be the main reason that causing the genetic differentiation of F.tikoua.Besides,the results of species ecological distribution model showed F.tikoua's populations disconnectedly distributed at north part of Sichuan Basin and East part of Yungui plateau during LIG?last interglacial?.Geographic isolation during LIG and climate change leading to F.tikoua's population differentiation.