Genetic diversity and structure of natural and managed populations of Cedrus atlantica (Pinaceae) assessed using random amplified polymorphic DNA

Cedrus atlantica (Pinaceae) is a large and exceptionally long-lived conifer native to the Rif and Atlas Mountains of North Africa. To assess levels and patterns of genetic diversity of this species, samples were obtained throughout the natural range in Morocco and from a forest plantation in Arbúcies, Girona (Spain) and analyzed using RAPD markers. Within-population genetic diversity was high and comparable to that revealed by isozymes. Managed populations harbored levels of genetic variation similar to those found in their natural counterparts. Genotypic analyses of molecular variance (AMOVA) found that most variation was within populations, but significant differentiation was also found between populations, particularly in Morocco. Bayesian estimates of F(ST) corroborated the AMOVA partitioning and provided evidence for population differentiation in C. atlantica. Both distance- and Bayesian-based clustering methods revealed that Moroccan populations comprise two genetically distinct groups. Within each group, estimates of population differentiation were close to those previously reported in other gymnosperms. These results are interpreted in the context of the postglacial history of the species and human impact. The high degree of among-group differentiation recorded here highlights the need for additional conservation measures for some Moroccan populations of C. atlantica.     

Geographic pattern of genetic variation in Pinus resinosa: area of greatest diversity is not the origin of postglacial populations

Genetic diversity is low in natural populations of red pine, Pinus resinosa, a species that has a vast range across north-eastern North America. In this study, we examined 10 chloroplast microsatellite or simple sequence repeats (cpSSR) loci in 136 individuals from 10 widespread populations. Substantial variation for the cpSSR loci was observed in the study populations. The contrast with red pine's lack of variation for other types of loci is likely to be due to the higher mutation rates typical of SSR loci. The amount of variation is lower than that generally found for cpSSR loci in other pine species. In addition, the variation exhibits a striking geographical pattern. Most of the genetic diversity is among populations, with little within populations, indicating substantial isolation of and genetic drift within many populations in the southern half of the species distribution. The greatest diversity now occurs in the north-eastern part of New England, which is especially intriguing because this entire area was glaciated. Thus the centre of diversity cannot be the origin of postglacial populations, rather it is likely caused by admixture, most probably because of influences from two separate refugia. Furthermore, the pattern indicates that the spread of red pine since the last glaciation is rather more complex than usually described, and it likely includes more than one refugia, complex migration routes, and postglacial-retreat isolation and genetic drift among shrinking populations in regions of the present southern range.     

Genetic structure of gall oak (<Emphasis Type="Italic">Quercus infectoria</Emphasis>) characterized by nuclear and chloroplast SSR markers

Quercus infectoria, commonly known as gall oak, is a small shrub found in Iran. Unfortunately, it is subjected to genetic erosion, and so, its conservation and evaluation are desirable. Thus, in the current research, 16 microsatellite primer pairs (seven nuclear simple sequence repeats (nSSRs) and nine chloroplast simple sequence repeats (cpSSRs)) were used in an attempt to assess the genetic diversity of 121 individuals of Q. infectoria belonging to 11 populations from three provinces in northern Zagros forests of Iran. In total, 69 alleles of nSSR and 18 alleles of cpSSR were detected among the individuals. The results of the overall analysis of molecular variance based on nSSRs indicated that 89.00% of the variation was due to differences within populations and 11.00% occurred among populations, while according to cpSSRs, 94.00% of the variation resided among populations, and only 6.00% could be attributed to variation within populations. A higher genetic differentiation of Q. infectoria populations was found according to cpSSR data in comparison to nSSR data. Cophenetic correlation coefficient values were statistically insignificant between nSSR and cpSSR data. The unweighted pair group method with arithmetic mean and Bayesian cluster analyses grouped the studied individuals into two main clusters based on both nSSR and cpSSR data. nSSR data could not completely clustered individuals next each other according to their geographical collection area. Information detailed by nSSR loci revealed that north-Zagros gall oak preserves average levels of genetic diversity at the species level, high level of within-population genetic diversity, and moderate level of genetic variation among populations. The present results provide valuable data for in situ or ex situ conservation and utilization of the studied germplasm.     

内蒙古高原小叶锦鸡儿(Caragana microphylla)、中间锦鸡儿(C. davazamcii)和柠条锦鸡儿(C. korshinskii)的遗传多样性及遗传关系

采用RAPD技术对10个具较大地理跨度的小叶锦鸡儿、中间锦鸡儿和柠条锦鸡儿种群的遗传多样性和遗传关系进行了研究.共检测到678个位点,多态条带比率(PPB)为100%;特有位点41个,占6.05%.总体上3种锦鸡儿的遗传多样性表现出自东向西递减的趋势,分析表明其与生长地点年均气温呈显著负相关.AMOVA表明:3种锦鸡儿种间变异只占总体变异的6.08%,且显著性检验表明这种变异不显著;种内种群间的变异占总变异的11.90%;总变异的主要部分来自种群内部(82.02%). 3种锦鸡儿各种群总体分析结果表明:种群内变异比率Hpop/Hsp为0.8013,基因分化系数Gst为0.1603,种群每代迁移数Nm为2.6192,显示种群间存在一定强度的基因流,3种锦鸡儿间表现为异交性.3种锦鸡儿多样性高低及种群聚类分布格局都表现出一定的地理连续性.     

Genetic diversity and genetic relationship of Caragana microphylla, Caragana davazamcii and Caragana korshinskii on the Inner Mongolia Plateau, China

C. microphylla, C. davazamcii and C. korshinskii exhibit a geographical replacement series from east to west on the Inner Mongolia Plateau. Currently, there is still a debate about the taxonomic and genetic relationship among these 3 species. We studied the genetic diversity and genetic relationship among these 3 species by analyzing DNA samples of individual plants from within 10 populations with random amplified polymorphic DNA (RAPD) markers. We identified 678 RAPD loci in total, of which all were polymorphic (PPB = 100%). There were 41 unique loci (6.05%). In general, a trend presented that the genetic diversity of these species decreased from east to west. Further, the genetic diversity was significantly negatively correlated with the local annual mean temperature. Analysis of molecular variation (AMOVA) showed that the genetic variation among these 3 species was only 6.08% of the total genetic variation. Between the species, the genetic variation was insignificant (P = 0.9961). The proportion of genetic variation among populations within each species was 11.90% (P < 0.001) of the total genetic variation, and the total genetic variation mainly existed within the populations (82.02%). Estimated with Shannon's index, genetic differentiation within the populations (Hpop/Hsp) was 0.8013, the coefficient of gene differentiation (Gst) was 0.1603, and the gene flow index (Nm) was 2.6192. This, thus, indicates that there is relatively high gene flow among these populations, and that these 3 species are crossbreeding. The genetic diversity level and the population distribution pattern showed geographic continuity to some extent.     

Genetic variation in wild sorghum (Sorghum bicolor ssp. verticilliflorum (L.) Moench) germplasm from Ethiopia assessed by random amplified polymorphic DNA (RAPD)

The extent and distribution of genetic variation in wild sorghum (Sorghum bicolor ssp. verticilliflorum (L.) Moench) collected from five different geographical regions in Ethiopia were analyzed using random amplified polymorphic DNA (RAPD) markers for 93 individuals representing 11 populations. Nine decamer primers generated a total of 83 polymorphic bands with 8-12 bands per primer and a mean of 9 bands across the 93 individuals. The amount of genetic variation among the populations (H = 0.37) and among the geographical region (H = 0.44) was low to moderate, despite the high degree of polymorphic bands per primer. Similarly, the mean genetic distance (0.08) among populations as well as among regions of origin (0.04) of the population was found to be low. The low genetic variation may be due to the reduced population size of the wild sorghum in Ethiopia because of habitat change. Partitioning of the genetic variation into between and within the population as well as between and within the regions of origin revealed that 75% and 88% of the variation was found within the populations and within the regions, respectively. Cluster analysis of genetic distance estimates further confirmed low level of differentiation of wild sorghum populations both on population and regional bases. The implications of the results for genetic conservation purposes are discussed.     

A range wide geographic pattern of genetic diversity and population structure of Castanea mollissima populations inferred from nuclear and chloroplast microsatellites

Understanding geographical pattern of genetic diversity and population structure is of great importance for formulating conservation and utilization strategies. In this study, we investigated the genetic diversity and population structure of 28 natural populations of Castanea mollissima in China using eight nuclear and six chloroplast microsatellite makers (nSSRs and cpSSRs). Populations from central China harbored the highest genetic diversity at both nSSR and cpSSR markers (nSSR: H _E?=?0.705; cpSSR: H?=?0.461). The standardized measure of genetic differentiation estimated as G′ _ST was 0.447 for nSSR and 0.803 for cpSSR, respectively. The G′_ST-based pollen to seed flow ratio is 3.043, indicating that pollen flow is not extensive among C. mollissima populations. No obvious population genetic structure by geographical locations was found by STRUCTURE analysis based on nSSR data, and similarly, no signal of phylogeographic structure was detected for cpSSR analysis. Five boundaries defining zones of maximum genetic differences within the network of the C. mollissima populations were found, and the locations of those barriers were consistent with those of four mountains, i.e., Daloushan Mountain, Dabashan Mountain, Wushan Mountain, and Qingliangfeng Mountain, indicating that those mountains might act as genetic barriers obstructing the genetic exchange among natural C. mollissima populations. These results provide valuable baseline data for conservation and utilization of this species.     

Chloroplast microsatellite diversity of Clintonia udensis (Liliaceae) populations in East Asia

Nineteen populations of Clintonia udensis Trautv. & Mey. were examined to quantify genetic diversity and genetic structure by chloroplast DNA microsatellites (cpSSR). Significant cpSSR genetic diversity (PPB = 63.64%) was detected in this species. Tetraploid populations demonstrated approximately the same level of genetic diversity as the diploid ones. A significant differentiation, however, was found between tetraploids and diploids. Most of the sixteen chloroplast haplotypes were limited to a single population. The level of haplotype diversity was high (Hd = 0.915). AMOVA, PCA and Bayesian clustering analysis revealed that there were significant genetic differences among populations. Inter-population genetic distances among population sites correlated significantly with geographic distances. These results indicate that the mixed-mating – breeding system, limited gene flow, environmental stress, and historical factors may be the main factors causing geographical differentiation in the genetic structure of C. udensis.     

High genetic diversity and significant population structure in Cedrus brevifolia Henry, a narrow endemic Mediterranean tree from Cyprus

Endemic island plant species with a narrow distribution are often, but not always, linked to low genetic variation within populations and a lack of differentiation among populations. Cedrus brevifolia is a narrow endemic island tree species of Cyprus. Its range is restricted to a single forest, divided into five neighbouring sites. This study, using biparentally inherited nuclear microsatellites and paternally inherited plastid (chloroplast) microsatellites, assessed the genetic variation of C. brevifolia within its sole population and the level of genetic differentiation among formed sites. The results from both markers showed high diversity (nuclear H _T?=?0.70; plastid H _T?=?0.93), strongly suggesting that the species did not experience severe bottleneck events or extensive genetic drift. Besides, the maintenance of a high genetic diversity in C. brevifolia may suggest that it originates from a widespread congener species. Significant genetic differentiation at nuclear (G _ST?=?0.052) and plastid (G _ST?=?0.119) markers was found among the formed sites. Remarkably, the relatively high genetic differentiation found at plastid markers was comparable to values observed in two widespread congener cedar species. The genetic differentiation probably occurred due to fragmentation of a previously uniform population. This would lead to the shaping of different genetic groups (Bayesian analysis) and to significant population substructure. Furthermore, significant values observed for both isolation by distance and large-scale spatial genetic structure could indicate ineffective gene flow among sites and the early geographical isolation of the more isolated sites from the core population.     

Spatial and temporal population genetic variation and structure of Nothotsuga longibracteata (Pinaceae), a relic conifer species endemic to subtropical China

Nothotsuga longibracteata, a relic and endangered conifer species endemic to subtropical China, was studied for examining the spatial-temporal population genetic variation and structure to understand the historical biogeographical processes underlying the present geographical distribution. Ten populations were sampled over the entire natural range of the species for spatial analysis, while three key populations with large population sizes and varied age structure were selected for temporal analyses using both nuclear microsatellites (nSSR) and chloroplast microsatellites (cpSSR). A recent bottleneck was detected in the natural populations of N. longibracteata. The spatial genetic analysis showed significant population genetic differentiation across its total geographical range. Notwithstanding, the temporal genetic analysis revealed that the level of genetic diversity between different age class subpopulations remained constant over time. Eleven refugia of the Last Glacial Maximum were identified, which deserve particular attention for conservation management.     

七筋菇自然居群的遗传结构分析

采用ISSR分子标记,对七筋菇(Clintonia udensis)17个居群的遗传多样性与遗传结构进行了研究。结果表明:七筋菇不同居群的多态位点百分率PPB为11.90%~59.52%,总的多态位点百分率PPB为98.8%,具有高的遗传多样性。Shannon多样性指数(0.6903)和基因分化系数(GST=0.6944)均揭示出七筋菇居群间存在明显的遗传差异,AMOVA分析结果也显示遗传变异主要发生在居群之间(81.47%),而居群内部的遗传变异仅为18.53%。七筋菇居群间的遗传距离从0.1871~0.6632,平均为0.3838,大于同一物种居群间的平均遗传距离值(0.05),同样表明七筋菇居群间的遗传多样性存在较大差异。七筋菇居群间的基因流Nm=0.2200,远远低于一般广布种植物的基因流(Nm=1.881)。Mantel检测显示居群间的遗传距离与地理距离之间没有显著相关性(r=0.029,P=0.3196)。七筋菇分布范围广以及其进化历史是其具有高遗传多样性的原因;居群间存在较高遗传变异可能是由于七筋菇本身的生物学特性、有限的基因流以及遗传漂变等原因造成的。     

日本落叶松群体的叶绿体SSR分析

利用叶绿体微卫星（cpSSR）分子标记对日本国内的7个日本落叶松（Larix kaempferi）群体遗传结构进行了研究。11对cpSSR引物中筛选出的3对多态性引物,共产生10个长度不同片段,在197个样品中组合出现10个不同的单倍型（haplotype）。各群体的单倍型差异较大。cpSSR基因座揭示了日本落叶松的遗传变异：平均等位基因数A=3.33,平均有效等位基因数NE=1.20,基因多样度HE=0.17,群体间变异占总群体变异的5.37%,遗传变异主要来自于群体内个体间。Abstract: Genetic structure of seven populations in Larix kaempferi in Japan was studied by use of cpSSR markers. Ten different length fragments in and ten different kinds of haplotypes were reduced in 197 samples based on 3 pairs of polymorphic primers screened from 11 pairs of primers. There were significant variant haplotypes among the populations. The genetic variation in the populations of Larix kaempferi was detected by using cpSSR with the number of average loci A=3.33, the number of average efficient loci NE=1.20, gene diversity HE=0.17 and 5.37% variation from different populations. The genetic variation was mainly from individuals in population.     

Stem anatomy of Rhipsalis (Cactaceae) and its relevance for taxonomy

We used paternally inherited chloroplast microsatellites (cpSSR) to study population genetic structure in the endemic and highly restricted Serbian spruce Picea omorika. Fragment size polymorphism at the five cpSSR regions that could be amplified out of the nine tested combined into only four different haplotypes in the seven populations studied. Mean total haplotypic diversity was H _T = 0.395, and mean within-population diversity was H _s = 0.279. Haplotypic variation was lower than in most conifers described so far and partitioned into two geographical groups. All northern P. omorika populations were fixed or nearly fixed for the common haplotype, while southern populations exhibited two to three haplotypes. We suggest that current P. omorika populations are shaped by extreme demographic bottleneck and random genetic drift linked to Quaternary glacial cycles. P. omorika thus belongs to the small group of genetically depauperate tree species.     

Phylogeography of North African Atlas cedar (Cedrus atlantica, Pinaceae): Combined molecular and fossil data reveal a complex Quaternary history

Northwest Africa is a major hotspot of plant biodiversity, but very little is known about the Quaternary range dynamics of plant species in this region. Here we investigate the range-wide population structure and phylogeography of Atlas cedar (Cedrus atlantica), an emblematic forest tree endemic to Morocco and Algeria. We genotyped 261 individuals from 11 populations using AFLP markers. Data were analyzed using both conventional F(ST)-based techniques and Bayesian clustering. Overall population differentiation was high (F(ST) = 0.25). Two major groups of populations were identified, one distributed through the Rif and Middle Atlas mountains in Morocco and the other through the Algerian Tell Atlas and Aurès mountains as well as the Middle Atlas. Combined molecular and fossil data indicate that C. atlantica survived the Last Glacial Maximum in at least three disjunct refugia along the coast of the Mediterranean Sea, whereas the Middle Atlas, today the core of the species range, has been colonized relatively recently (<10000 yr BP). The colonization history of individual populations has left clear imprints in their present-day diversity, which may vary greatly even between nearby stands. Our study illustrates how integrating different data sources and analytical approaches can help elucidate complex range dynamics that would otherwise remain undeciphered.     

Population differentiation and gene flow within a metapopulation of a threatened tree, Magnolia stellata (Magnoliaceae)

We examined genetic differentiation among eight local populations of a metapopulation of Magnolia stellata using 10 nuclear and three chloroplast microsatellite (nSSR and cpSSR) markers and evaluated the influence of historical gene flow on population differentiation. The coefficient of genetic differentiation among populations for nSSR (F(ST) = 0.053) was less than half that for cpSSR (0.137). An isolation-by-distance pattern was detected for nSSRs, but not cpSSRs. These results suggest that pollen flow, as well as seed dispersal, has significantly reduced genetic differentiation among populations. We also examined patterns of contemporary pollen flow by paternity analysis of seeds from nine seed parents in one of the populations using the nSSR markers and found it to be greatly restricted by the distance between parents. Although most pollen flow occurred within the population, pollen flow from outside the population accounted for 2.5% of the total. When historical and contemporary pollen flows among populations were compared, the levels of pollen flow seem to have declined recently. We conclude that to conserve M. stellata, it is important to preserve the whole population by maintaining its metapopulation structure and the gene flow among its populations.     

金花茶遗传多样性的ISSR分析

采用ISSR分子标记对金花茶的4个自然分布居群的126份样品的遗传多样性水平进行了研究。用12条引物,共检测到105个清晰的扩增位点,其中多态性位点79个,多态位点百分率(PPB)为75．24％。采用POPGENE软件进行分析,结果表明：居群总的Nei’s基因多样性指数为0．2302,Shannon信息多态性指数为0．3502,金花茶总的遗传多样性水平较高。但金花茶居群内的遗传多样性相对较低。基因分化系数为0．5752,遗传变异主要存在于居群间。用NTSYS软件对样品进行UPGMA聚类分析,结果4个居群的样品各自聚在一起,而金花茶两间断分布区区内的居群又各自聚在一起。金花茶4个居群间的遗传距离与地理距离呈显著的正相关(r=0．68261,P=1．0000)。     

基于微卫星标记的中国东北地区灰飞虱遗传变异及种群遗传结构分析

【目的】本研究旨在明确我国东北地区灰飞虱Laodelphax striatellus种群遗传变异及种群遗传结构,阐明种群间遗传分化与基因流。【方法】利用9对微卫星引物对采自我国东北地区15个地理种群的375头灰飞虱样品进行测序与分析;利用GeneAlex6.51,GENEPOP4.0.9和STRUCTURE 2.3.4等软件分析灰飞虱地理种群间的遗传多样性、遗传分化、基因流及种群遗传结构。【结果】在所分析的375头灰飞虱个体中,各位点平均有效等位基因数Na=6.898;总体上,灰飞虱不同地理种群遗传多样性较高(平均观测杂合度Ho=0.548;平均期望杂合度He=0.582),各种群间基因流较低(Nm=0.660)。UPGMA聚类树、PCoA及STRCTURE分析结果表明,东北地区灰飞虱种群分为两分支:吉林(JL)和沈阳(SY2012,SY2013和SY2014)种群聚为一支;其余种群聚为一支。AMOVA分析结果表明,灰飞虱遗传变异主要来自种群内(87%),种群间变异水平较低(13%)。【结论】中国东北地区灰飞虱遗传多样性较高,不同地理种群存在一定程度的遗传分化,且基因交流较低,存在一定的种群遗传结构。     

Genetic variation of Calycophyllum spruceanum in the Peruvian Amazon Basin, revealed by amplified fragment length polymorphism (AFLP) analysis

An understanding of the level, structure and origin of genetic variation within and among populations of tropical trees is essential for devising optimum management strategies for their sustainable utilization and conservation. Here, amplified fragment length polymorphism (AFLP) analysis was used to partition genetic variation within and among nine populations of the predominantly riverine tree, Calycophyllum spruceanum , sampled across a wide geographical range along river tributaries of the Peruvian Amazon Basin. Analysis of molecular variance ( AMOVA ) employed 65 AFLP markers and revealed most variation among individuals within populations (91%), although variation among populations was highly significant ( P < 0.001). Calculation of genetic distances and nested AMOVA indicated a degree of structuring among populations based on geographical proximity, although clustering did not depend on geographical distance alone. No firm evidence was obtained for unidirectional seed dispersal by water playing an important role in determining genetic structure over the geographical range sampled. Implications of data for optimising genetic management of the species are discussed and areas for further study identified.     

猕猴桃属植物的cpSSR遗传多样性及其同域分布物种的杂交渐渗与同塑

同域分布的近缘物种常常发生杂交而导致种间基因渐渗, 从而对相关物种的自然居群遗传结构产生重要影响, 近缘种间的杂交渐渗已成为进化生物学和保护生物学关注的热点。本研究采用8对cpSSR引物对我国西部高原台地向中东部丘陵平原过渡地带同域重叠分布的猕猴桃属(Actinidia)7个物种的自然居群遗传多样性、居群遗传结构和同域分布种间遗传分化进行了检测。结果表明: (1)在6个多态性位点检测到18个等位基因形成的42个单倍型, 尽管各单倍型间显示了复杂的网状进化关系, 但还是具有明显的物种特异性; (2)各物种有丰富的cpSSR遗传多样性, 但种间存在较大差异, 绵毛猕猴桃(Actinidia fulvicoma var. lanata)的遗传多样性水平最高(P = 62.50%, h_T = 0.173, H_T = 0.897), 美味猕猴桃(A. deliciosa)的最低(P = 37.5％, h_T = 0.041, H_T = 0.516); (3)尽管不同物种的居群分化程度存在较大差异, 但种内居群间存在明显分化(G_ST为0.319–0.780, F_ST为0.401–0.695), 居群间的基因流不足(N_m为0.219–0.747<1); 其中以美味猕猴桃的居群遗传分化度最高(G_ST = 0.780, F_ST = 0.695); (4)遗传分化系数G_ST(unordered alleles)与N_ST(ordered alleles)无显著差异, 揭示本研究的大多数猕猴桃属物种不存在系统地理结构, 与用Mantel检验得出的居群遗传距离和地理距离不存在显著性相关的结果一致; (5)除了中华/美味猕猴桃复合体(A. chinensis / A. deliciosa complex)的湖北五峰(HW)和广西资源(GZ)两个同域复合居群外, 同域分布的物种间遗传分化强烈(F_ST为0.476–0.990), 与UPGMA聚类时多数居群按各自物种聚类的结果一致。进一步分析表明, 中华/美味猕猴桃复合体近缘种间存在明显的共祖多态性和杂交渐渗现象, 近缘种植株分布的交错程度以及是否存在亚居群结构对杂交渐渗存在着重要影响。亲缘关系较远的物种间杂交渐渗事件稀少, 但存在个别同塑事件。本研究结果有助于进一步了解猕猴桃属植物自然居群cpDNA的遗传特性和渐渗杂交进化模式, 为我国猕猴桃野生种质资源保育及可持续开发利用提供基础数据和科学依据。     

DNA from bird-dispersed seed and wind-disseminated pollen provides insights into postglacial colonization and population genetic structure of whitebark pine (Pinus albicaulis)

Uniparentally inherited mitochondrial (mt)DNA and chloroplast (cp)DNA microsatellites (cpSSRs) were used to examine population genetic structure and biogeographic patterns of bird-dispersed seed and wind-disseminated pollen of whitebark pine (Pinus albicaulis Engelm.). Sampling was conducted from 41 populations throughout the range of the species. Analyses provide evidence for an ancestral haplotype and two derived mtDNA haplotypes with distinct regional distributions. An abrupt contact zone between mtDNA haplotypes in the Cascade Range suggests postglacial biogeographic movements. Among three cpSSR loci, 42 haplotypes were detected within 28 cpSSR sample populations that were aggregated into six regions. Analysis of molecular variance (amova) was used to determine the hierarchical genetic structure of cpSSRs. amova and population pairwise comparisons (FST ) of cpSSR, and geographical distribution of mtDNA haplotypes provide insights into historical changes in biogeography. The genetic data suggest that whitebark pine has been intimately tied to climatic change and associated glaciation, which has led to range movements facilitated by seed dispersal by Clark's nutcracker (Nucifraga columbiana Wilson). The two hypotheses proposed to explain the genetic structure are: (i) a northward expansion into Canada and the northern Cascades in the early Holocene; and (ii) historical gene flow between Idaho and the Oregon Cascades when more continuous habitat existed in Central Oregon during the late Pleistocene. Genetic structure and insights gained from historical seed movements provide a basis on which to develop recovery plans for a species that is at risk from multiple threats.