Phylogeography Of Potentilla Anserina L.distributed Over The Qinghai-Tibet Plateau

Potentilla anserina L.is a perennial herb belonging to the genus Potentilla L.of family Rosaceae,widely distributed in the Qinghai-Tibet Plateau?QTP?.In this study,phylogeographic study of P.anserina was performed by sequencing one chloroplast DNA?cpDNA?intergenic spacers?trnL-trnF?and one nuclear internal transcribed spacer?ITS 18S-26A?from 30 populations?603-714 individuals?in the QTP.Genetic variations within and among populations was detected,glacial refugia and evolutionary history of P.anserina have been discussed.The main results are as follows:?1?A total of 603 individuals were successfully amplified for the trnL-trnF intergenic spacer,and the alignment length was 727 bp.Twenty-two mutation sites were discovered,and the percentage of variation sites was 3.03%.The average nucleotide diversity of trnL-trnF among the 30 populations of P.anserina was0.010641.A total of 40 haplotypes were detected,16 shared haplotypes were widely distributed in all populations,and the rest were population-specific haplotypes.These population-specific haplotypes were randomly distributed in the whole distribution range.The population generally has high haplotype diversity?h?and/or nucleotide diversity?pi?.The analysis of cpDNA trnL-trnF fragments showed that the total genetic diversity and the average genetic diversity within the population were very high?H_T=0.849,H_S=0.640?.The degree of genetic differentiation between populations in the whole distribution area was low(G_ST=0.246,N_ST=0.109).A comparison between N_STand G_STT showing an absence of phylogeographic structure across the distribution range of P.anserina(N_ST>G_ST,P<0.01).Analysis of molecular variance?AMOVA?showed that the genetic variation mainly resided within populations?59.69%?and the F_STT was 0.40313.?2?A total of 714 individuals were successfully amplified for the ITS fragments,and the alignment length was 565 bp.Fifty-nine mutation sites were discovered,and the percentage of variation sites was 10.4%.The average nucleotide diversity of ITS among the 30 populations of P.anserina was 0.003584.A total of 128 haplotypes were detected,42 shared haplotypes were widely distributed in all populations,and the rest were population-specific haplotypes.These population-specific haplotypes were randomly distributed in the whole distribution range.The population generally has high haplotype diversity?h?and/or nucleotide diversity?pi?.The analysis of ITS fragments showed that the total genetic diversity and the average genetic diversity within the population were very high?H_T=0.844,H_S=0.763?.The degree of genetic differentiation between populations in the whole distribution area was high(G_ST=0.096,N_ST=0.522).A comparison between N_STand G_STT showing an absence of phylogeographic structure across the distribution range of P.anserina(N_ST>G_ST,P<0.01).Analysis of molecular variance?AMOVA?showed that the genetic variation mainly resided within populations?54.09%?and the F_STT was 0.45911.?3?The results of niche model test showed the predicted distribution of P.anserina underwent significant changes during the glacial-interglacial period.From the last interglacial maximum to the last glacial maximum to the mid-Holocene,the range of the predicted distribution of P.anserina experienced successive reduction and expansion.There was no significant change from the mid-Holocene to the current period.The following conclusions can be drawn:?1?The similar haplotypes of P.anserina occur in the same population and have obvious pedigree geographical relationship.?2?Bifurcation distribution analysis showed that the distribution map showed a multi-peak curve,indicating that P.anserina population developed steadily over a long period of time and did not experience sudden recent expansion.?3?It is believed that P.anserina may have at least three ice age refuges in the QTP and its adjacent mountainous areas,namely,the southern margin of the southern Tibetan valley,the northeastern margin of the Qinghai Plateau and the southern margin of the Sichuan-Tibet alpine valley.The distribution pattern of P.anserina in the QTP and its adjacent mountainous areas is mainly a combination of Quaternary glacial-interglacial climate turbulence and uplift of the QTP.?4?The reconstructed results of the present,mid-Holocene,last glacial maximum?LGM?,and last maximum interglacial period?LIM?strongly support the conclusion that the distribution of P.anserina contracted sharply and expanded again after mid-Holocene.