Extremely high diversity in populations of Oxytropis aciphylla at northern boundary of its distribution range
摘要
Based on nucleotide polymorphism of cpDNA intergenic spacers psbA-trnH, trnL-trnF, and trnS-trnG, we studied the genetic diversity of Oxytropis aciphylla populations at the northern edge of the species’ range and the phylogenetic relationships of O. aciphylla and O. tragacanthoides, two species from the subgenus Tragacanthoxytropis. As a result, we have found in the populations of O. aciphylla a number of features that are unusual for marginal populations: a high level of genetic diversity, both haplotype (h varies from 0.733 to 1.000) and nucleotide (π varies from 0.0027 to 0.0286), and such level of nucleotide diversity is not typical of Oxytropis species; a high percentage of private haplotypes (85.7%) and the absence of shared haplotypes in closely located populations; and a significant nucleotide divergence between populations (DXY varies from 0.00207 to 0.00589). All the above findings indicate the relict status of the populations under study and the existence of microrefugia in this area. We observed local demographic expansion for four of six O. aciphylla populations. A study of the phylogenetic relationships between the haplotypes of O. aciphylla and O. tragacanthoides has revealed a great genealogical depth, both between species and within populations of each species.