Genetic Structure of the Tree Peony (Paeonia rockii) and the Qinling Mountains as a Geographic Barrier Driving the Fragmentation of a Large Population

Abstract

BackgroundTree peonies are great ornamental plants associated with a rich ethnobotanical history in Chinese culture and have recently been used as an evolutionary model. The Qinling Mountains represent a significant geographic barrier in Asia, dividing mainland China into northern (temperate) and southern (semi–tropical) regions; however, their flora has not been well analyzed. In this study, the genetic differentiation and genetic structure of Paeonia rockii and the role of the Qinling Mountains as a barrier that has driven intraspecific fragmentation were evaluated using 14 microsatellite markers.Methodology/Principal FindingsTwenty wild populations were sampled from the distributional range of P. rockii. Significant population differentiation was suggested (FST value of 0.302). Moderate genetic diversity at the population level (HS of 0.516) and high population diversity at the species level (HT of 0.749) were detected. Significant excess homozygosity (FIS of 0.076) and recent population bottlenecks were detected in three populations. Bayesian clusters, population genetic trees and principal coordinate analysis all classified the P. rockii populations into three genetic groups and one admixed Wenxian population. An isolation-by-distance model for P. rockii was suggested by Mantel tests (r = 0.6074, P<0.001) and supported by AMOVA (P<0.001), revealing a significant molecular variance among the groups (11.32%) and their populations (21.22%). These data support the five geographic boundaries surrounding the Qinling Mountains and adjacent areas that were detected with Monmonier's maximum-difference algorithm.Conclusions/SignificanceOur data suggest that the current genetic structure of P. rockii has resulted from the fragmentation of a formerly continuously distributed large population following the restriction of gene flow between populations of this species by the Qinling Mountains. This study provides a fundamental genetic profile for the conservation and responsible exploitation of the extant germplasm of this species and for improving the genetic basis for breeding its cultivars.

Phylogeographic Patterns of mtDNA Variation Revealed Multiple Glacial Refugia for the Frog Species Feirana taihangnica Endemic to the Qinling Mountains

“…Some refugia proposed by this study (Fig. 2c) are corroborated by other case studies; for example, the WQM, MQM, and FNM were considered as refugia for the tree peony (Paeonia rockii) (Yuan et al 2012), the WQM was a refugium for the Chinese Hwamei (Leucodioptron canorum canorum) , and the WQM, MQM, and EQM were refugia for the Gray-cheeked Fulvetta (Alcippe morrisonia) during the Pleistocene ice ages (Song et al 2009). Certainly, we need more cases to make generalizations about the genetic and demographic legacies of the glacial oscillations on organisms in this region.…”

Genetic structure of Pinus henryi and Pinus tabuliformis: Natural landscapes as significant barriers to gene flow among populations

“…Mitochondrial DNA analysis revealed the same spatial pattern, which suggested that they might come from different refugia in the Qinling area (Chen et al, 2008;unpublished data). Interestingly, populations of Paeonia rochii in the Qinling Mountains can also be grouped into eastern and western Qinling genetic clusters (Yuan et al, 2012). Plant populations in this area probably have experienced a common history with past fragmentation of a large population and low dispersal rates.…”

Genetic diversity of wild Prunus cerasifera Ehrhart (wild cherry plum) in China revealed by simple-sequence repeat markers

“…Simple-sequence repeat (SSR) markers are powerful tools for investigating the population genetics of wild species (Yuan et al, 2012;Zhai et al, 2012). Within the genus Prunus, numerous SSR markers have been developed, including markers for peach (Cipriani et al, 1999;Testolin et al, 2000;Dirlewanger et al, 2002), cherry (Downey and Iezzoni, 2000;Struss et al, 2003), and Japanese plum (Mnejja et al, 2004), and are transferable between species for genetic diversity analyses (Downey and Iezzoni, 2000;Dirlewanger et al, 2002).…”