Data_Sheet_1_Population Structure and Genetic Diversity Within the Endangered Species Pityopsis ruthii (Asteraceae).XLSX

Pityopsis ruthii (Ruth’s golden aster) is a federally endangered herbaceous perennial endemic to the Hiwassee and Ocoee Rivers in southeastern Tennessee, United States. Comprehensive genetic studies providing novel information to conservationists for preservation of the species are lacking. Genetic variation and gene flow were evaluated for 814 individuals from 33 discrete locations using polymorphic microsatellites: seven chloroplast and twelve nuclear. A total of 198 alleles were detected with the nuclear loci and 79 alleles with the chloroplast loci. Gene flow was estimated, with the Hiwassee River (Nm = 2.16; FST = 0.15) showing higher levels of gene flow and lower levels of population differentiation than the Ocoee River (Nm = 1.28; FST = 0.19). Population structure was examined using Bayesian cluster analyses. Nuclear and chloroplast analyses were incongruent. From the chloroplast microsatellites, three clusters were identified; all were present in sampling sites at both rivers, indicating a lack of allele fixation along rivers. Nuclear markers revealed two clusters and separated by river. When the Hiwassee River locations were analyzed, four clusters were identified for both the chloroplast and nuclear microsatellites, though the individuals clustered differently. Analysis of the Ocoee River revealed two clusters for the chloroplast microsatellites and three for the nuclear microsatellites. We recommend P. ruthii be managed as four populations for the Hiwassee River and three populations for the Ocoee River. Our results provide critical genetic information for P. ruthii that can be used for species management decisions to drive future population augmentation/reintroduction and ex situ conservation efforts.

露丝金菀（Pityopsis ruthii，英文名Ruth’s golden aster）是美国田纳西州东南部希瓦西河与奥科伊河流域特有的多年生草本植物，被列为联邦濒危物种。目前尚缺乏可为该物种保育工作者提供全新参考依据的综合性遗传学研究。
本研究利用7个多态性叶绿体微卫星（chloroplast microsatellites）位点与12个多态性核微卫星（nuclear microsatellites）位点，对源自33个独立采样点的814个个体开展遗传变异与基因流分析。核微卫星位点共检测到198个等位基因（allele），叶绿体微卫星位点则检测到79个等位基因（allele）。经基因流估算，希瓦西河种群的基因流水平（Nm=2.16；FST=0.15）高于奥科伊河种群（Nm=1.28；FST=0.19），种群遗传分化程度则更低。
研究采用贝叶斯聚类分析（Bayesian cluster analyses）对种群遗传结构进行解析。核微卫星与叶绿体微卫星的分析结果并不一致：基于叶绿体微卫星位点分析，共鉴定出3个遗传聚类组；两类河流的采样点均同时存在这3个聚类组，表明沿河流域未出现等位基因固定现象。核微卫星则鉴定出2个聚类组，且聚类结果与河流分布高度相关。
针对希瓦西河采样点单独分析时，叶绿体与核微卫星位点均鉴定出4个聚类组，但两类标记下的个体聚类模式存在差异。对奥科伊河采样点的分析则显示，叶绿体微卫星位点鉴定出2个聚类组，核微卫星位点则鉴定出3个聚类组。本研究建议，希瓦西河流域的露丝金菀应划分为4个管理种群，奥科伊河流域则划分为3个管理种群。
本研究结果可为露丝金菀提供关键遗传学依据，用于指导该物种的种群扩增/再引入与迁地保育（ex situ conservation）相关管理决策，助力后续种群恢复与保育工作开展。