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Distribution maps of Douglas-fir populations with their assignment to a variety (A), or to an intravarietal genetic cluster (B) as estimated by STRUCTURE. Populations R17, and R18 (map A) represent populations where individuals of both varieties, coastal (green color) and Rocky Mountain variety (blue color), were present. Dotted lines indicate the borders of the assumed intervarietal hybrid zone (von Rudloff 1973; Li and Adams 1989; Gugger et al. 2010; Wei et al. 2011). Map (B) displays eight intravarietal genetic clusters (I–VIII). Cluster-admixed populations (0.2 < Qvar < 0.8) are situated in overlapping (red dashed line) between two clusters I-II, I-(III+IV+V), and VI-VII. Black solid lines indicate glacial refugia based on fossil data detected by Gugger et al. (2010).
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Douglas-fir (Pseudotsuga menziesii) is one of numerous wide-range forest tree species represented by subspecies/varieties, which hybridize in contact zones. This study examined the genetic structure of this North American conifer and its two hybridizing varieties, coastal and Rocky Mountain, at intervarietal and intravarietal level. The genetic str...
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... Wei et al. 2011). Both fossil and marker based data show dissimilar- ities concerning the number of the last glacial refugia for both varieties. For the coastal variety, two refugia located within the current distribution area in the USA (on the Pacific coast in Oregon/Washington (OR/WA) and in California were strongly suggested by fossil records (Fig. 1B). Their existence was also mirrored in the phylogeographic pattern found in the terpenoids (Snajberk and Zavarin 1976). However, the two-refugium theory is in discordance with range-wide al- lozyme ( Li and Adams 1989) or recent mitochondrial DNA (mtDNA) and cpDNA phylogeographies Wei et al. 2011), which support the one refu- gium ...
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... total of 766 individuals representing 38 populations from the USA and Canada and covering the natural distribution range of the coastal and Rocky Mountain variety were col- lected (Table S1A and Fig. S1). Higher numbers of popula- tions were chosen to cover specific areas in OR and WA which are recommended for seed transfer to the majority of European countries (Breidenstein et al. 1990). A minimum of 20 individuals per population were used except for one population where samples from 18 individuals were col- lected. For 21 ...
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... PCoa and STRUCTURE analyses, the divergence time of both coastal variety and Rocky Mountain variety was estimated. We did it by applying Approximate Bayesian Computation (ABC) analysis in DIYABC, version 2.0 ( Cornuet et al. 2014) to all nuSSR loci. The intervarietal divergence was estimated using populations of the coastal (R01-R11, R16, R30, Fig. S1) and Rocky Mountain (R22-R26, Fig. S1) variety. These populations overlap with areas where Miocene and Pleistocene fossils of Douglas-fir and a refugium for each variety characterized by cpDNA were detected ( ). Thereafter, in order to clarify possible refu- gial origin of the discovered genetic clusters, different putative historical ...
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... time of both coastal variety and Rocky Mountain variety was estimated. We did it by applying Approximate Bayesian Computation (ABC) analysis in DIYABC, version 2.0 ( Cornuet et al. 2014) to all nuSSR loci. The intervarietal divergence was estimated using populations of the coastal (R01-R11, R16, R30, Fig. S1) and Rocky Mountain (R22-R26, Fig. S1) variety. These populations overlap with areas where Miocene and Pleistocene fossils of Douglas-fir and a refugium for each variety characterized by cpDNA were detected ( ). Thereafter, in order to clarify possible refu- gial origin of the discovered genetic clusters, different putative historical scenarios were tested and dated ...
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... intervarietal-admixed individuals were omitted from these analyses. Following parameters were estimated: divergence time (t), effective population size of each population (N 1 , N 2 ), and effective population size of ancestor (N a ). As t was expressed in the number of gener- ations, we used an approximate average generation time of 100 years to convert it into years, following Gugger et al. ( , 2011). ...
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... genetic structure analysis performed by the software STRUCTURE allowed us to assign populations to both varieties (Fig. 1A). Except for four populations (R17, R18, R21, R39), all populations were clearly assigned either to the coastal variety with Qvar of > 0.9 or the Rocky Mountains variety with Qvar < 0.1 (Table S1B). Within the four populations, genotypes of both varieties (R17, R18) and/or larger numbers of intervarietal- admixed genotypes (R17, R18, ...
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... (R17, R18) and/or larger numbers of intervarietal- admixed genotypes (R17, R18, R21, and R39) were pres- ent. Consequently, the whole dataset was divided into two variety subsets representing the coastal and the Rocky Mountain variety with 25 (R01-R16, R19, R29, R30, R32, R34-R38) and 13 populations (R17, R20-R28, R33, R39), respectively (Fig. ...
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... variety subset was divided into three clusters, a northern (R38), a central (R03, R07-08, R10-13, R15-16, R19) and a southern cluster (R34-37). Nine populations (R01, R02, R04-R06, R09, R14, R29, and R30) represented cluster-mixed populations between the central and south- ern cluster and two (R14, R32) between central and northern cluster (Fig. 1B). The southern cluster was fur- ther subdivided into three clusters (III-V) with the popu- lations R34, R35, and R36-37 (Fig. 1B, Table S2B). In total, five geographically and genetically distinct coastal clusters (I-V) were detected including three in California, one in BC and one between these two regions (Fig. 1B, Table ...
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... cluster (R34-37). Nine populations (R01, R02, R04-R06, R09, R14, R29, and R30) represented cluster-mixed populations between the central and south- ern cluster and two (R14, R32) between central and northern cluster (Fig. 1B). The southern cluster was fur- ther subdivided into three clusters (III-V) with the popu- lations R34, R35, and R36-37 (Fig. 1B, Table S2B). In total, five geographically and genetically distinct coastal clusters (I-V) were detected including three in California, one in BC and one between these two regions (Fig. 1B, Table ...
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... central and northern cluster (Fig. 1B). The southern cluster was fur- ther subdivided into three clusters (III-V) with the popu- lations R34, R35, and R36-37 (Fig. 1B, Table S2B). In total, five geographically and genetically distinct coastal clusters (I-V) were detected including three in California, one in BC and one between these two regions (Fig. 1B, Table ...
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... compared to the coastal variety, the Rocky Mountain variety split into a smaller number of genetic clusters. Its 13 populations were divided into two clusters, cluster VIII (R22-R26) situated in the south of the Rocky Mountains and a cluster with the remaining populations (Fig. 1B, Table S2B). The latter was subsequently divided into clusters VI and VII. The populations R20, R27, R28, and R33 of cluster VI are distributed in the area of the Rocky Mountains in the north of the USA and the south- east of BC. The cluster VII lies to the far north of the dis- tribution area of the species in BC and contains only the ...
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... total, 25 individuals (with 0.2 < Qvar < 0.8) have been assigned to represent intervarietal-admixed geno- types by STRUCTURE (Fig. 2). The majority of these genotypes (21) were identified in all four populations (R17, R18, R21, and R39) located in interior BC (Fig. S1), whereas in the populations R17 and R18 individuals of both varieties were also recognized (Fig. S1, Fig. 2). The remaining four intervarietal-admixed individuals were identified in populations of coastal variety situated along slopes of the Cascades (R10, R15) in WA and in OR (R05) (Fig. S1). Within the Rocky Mountain variety, one ...
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... (with 0.2 < Qvar < 0.8) have been assigned to represent intervarietal-admixed geno- types by STRUCTURE (Fig. 2). The majority of these genotypes (21) were identified in all four populations (R17, R18, R21, and R39) located in interior BC (Fig. S1), whereas in the populations R17 and R18 individuals of both varieties were also recognized (Fig. S1, Fig. 2). The remaining four intervarietal-admixed individuals were identified in populations of coastal variety situated along slopes of the Cascades (R10, R15) in WA and in OR (R05) (Fig. S1). Within the Rocky Mountain variety, one such individual was found in the Blue Mountains of Oregon (R28). When extending the admixture bound- aries ...
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... (R17, R18, R21, and R39) located in interior BC (Fig. S1), whereas in the populations R17 and R18 individuals of both varieties were also recognized (Fig. S1, Fig. 2). The remaining four intervarietal-admixed individuals were identified in populations of coastal variety situated along slopes of the Cascades (R10, R15) in WA and in OR (R05) (Fig. S1). Within the Rocky Mountain variety, one such individual was found in the Blue Mountains of Oregon (R28). When extending the admixture bound- aries (Qvar) for intervarietal-admixed individuals (0.15 < Qvar < 0.85), 12 admixed individuals could be additionally recognized within beforehand mentioned populations (R10, R17, R18, R28, and ...
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... contrast to all previous studies, the nuSSRs revealed more detailed genetic structure of this variety by identify- ing five geographically distinct clusters (Table S6, Fig. 1B). How does the distribution of these clusters and their divergence correspond to the location of fossil-deter- mined glacial refugia and the postglacial colonization of this ...
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... of the cluster I (refugial population 1) in western OR and WA was consistent with the existence of a former refugium on the Pacific coast of these states and with postglacial colonization to the south (Califor- nia), to the east, where both slopes of the Cascades have primarily been colonized by it and to the north coloniz- ing southern BC (Fig. 1B). This glacial population, which all coastal clusters diverged from, even possessed the larg- est diversity indices of all clusters (Table S1A) as was also suggested in the refugia concept of Hewitt ...
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... California, where fossil records indicated the other refugium (Gugger and Sugita 2010), not one but three refugial (glacial) populations were discovered: one along the coast (cluster IV), one near the Sierra Nevada (cluster III) and one in the north (cluster V) (Fig. 1B); all with very similar Pleistocene divergence (56.9-40.1 ka, CI 197- 10.1 ka) from the more northerly situated glacial popula- tion I (Table S6). Such detailed structuring has not yet been discovered in this area. However, rare alleles, differ- ent ecotypes, or a separate chemical race are acknowl- edged from other studies for these ...
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... Such detailed structuring has not yet been discovered in this area. However, rare alleles, differ- ent ecotypes, or a separate chemical race are acknowl- edged from other studies for these sites Snajberk 1973, 1975;Klumpp 1999;). The location of the glacial population IV overlaps with refugium located in the unglaciated San Francisco Bay area (Fig. 1B). The glacial population III and V originated from other small-scale refugia. A similar phylogeographic pattern was revealed in Notho- lithocarpus densiflorus (tanoak), a forest tree associated with the Douglas-fir in California ( Nettel et al. 2009). Our hypothesis on the existence of three refugial areas in California is built on ...
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... comparing the distribution of the three nuSSR- based genetic clusters (VI-VIII, Fig. 1B) to the location of the three refugia recognized by fossils ( , then only the area of the southernmost cluster VIII with populations situated in Arizona, New Mexico and Colorado overlapped with a refugial area (Fig. 1B). Identical to the coastal variety, these southern situated glacial populations have diverged from more northerly ...
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... comparing the distribution of the three nuSSR- based genetic clusters (VI-VIII, Fig. 1B) to the location of the three refugia recognized by fossils ( , then only the area of the southernmost cluster VIII with populations situated in Arizona, New Mexico and Colorado overlapped with a refugial area (Fig. 1B). Identical to the coastal variety, these southern situated glacial populations have diverged from more northerly placed populations (cluster I of the coastal v., and clus- ter VI of the Rocky Mountain v.) in the Pleistocene. Similarly to this result, cpDNA types of Douglas-fir pop- ulations from the southern Rockies have been estimated ...
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... to be of younger origin than those found in the central US Rockies (Wei et al. 2011). The northern US Rockies cluster VI, which spread into BC and from which both the southern (VIII) and the northern glacial population (VII) have diverged, has most probably originated from one of the two central US Rockies refugia, which were described by (Fig. 1B). The absence of material from these areas did not allow to clarify ...
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... existence of one distinct glacial population for each variety (cluster II and VII) situated in the north of the current distribution area of Douglas-fir in BC (Fig. 1B) led to the question from which refugia these northern- most populations in BC originated. Based on the geo- graphic location of these populations and the divergence from the more southern refugial populations (I and VI) before the LGM (41.7 and 48.9 ka), we hypothesize that their origin is from two distinct cryptic and low-density ...
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... at the present eastern border of the hybrid zone (reflected by the coexis- tence of both varieties within populations R17, R18) fol- lowed by intervarietal hybridization and predominant unidirectional introgression into the coastal variety rather than assortative mating of F1 hybrids (R17, R18, R21, and R39) led to a 450-km wide hybrid zone in BC (Fig. 1A). A similar pattern was revealed using dominant markers by identifying an extensive and preferential pollen flow from east to the west of this hybrid zone, while seed-mediated gene flow remained geographically restricted ). In tree spe- cies, a high prevalence of introgressed genotypes over "true" hybrids is frequent and was also ...
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... the structure of the Douglas fir hybrid zone in Canada is more complex than previously described. From the four populations (two of each variety) which colonized BC in the Holocene, three of them contributed to the intervari- etal gene flow in addition to the intravarietal (interclus- ter) gene flow (cluster VI and VII with R18 and R21, Fig. 1B). Further studies with more detailed sampling design is needed to investigate this complex situation in ...
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Citations
... These 13 loci, as well as primers for their amplification by PCR, were developed by Slavov et al. (2004). Details of the analytical procedure used can be found in Neophytou (2019), Hintsteiner et al. (2018), andvan Loo et al. (2015). A population genetic analysis was carried out based on the genotypes identified and the genotypic data of 38 reference populations from the area of origin (Neophytou 2019). ...
Key message: We analyzed stem growth responses of Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) to severe drought in 2003/04 and 2018. The results showed high drought tolerance in sandy, loamy, and most silty soils, with limitations on clayey soils. This study indicates the susceptibility of Douglas-firs with shallow root systems to extreme drought and the importance of deep rooting for high drought resilience. Context: Although Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) is considered a more drought-tolerant substitute for Norway spruce (Picea abies (L.) Karst.) in Europe, there is considerable uncertainty about the drought tolerance of Douglas-fir under climate change, specifically concerning soil properties. Aims: This study aimed to assess the influence of soil texture, plant-available water capacity, and rooting characteristics on the interannual stem growth response of Douglas-fir when exposed to severe drought.
Methods: Along a soil texture gradient from sand to clay, we selected seven closely spaced sites at elevations of approximately 500 m a.s.l. in southern Germany. Mixed-effects models were used to analyze the effects of soil physical and rooting characteristics on growth response indices (resistance, recovery, resilience) related to the severe to extreme droughts in 2003/04 and 2018. Results: Douglas-fir showed high drought tolerance in sandy, loamy, and most silty soils. However, the results suggest a higher drought stress risk on clayey soils, as well as at specific silty sites with shallow root systems. A higher effective rooting depth increased the resilience of Douglas-fir during the extreme drought in 2018. Conclusion: Douglas-fir demonstrated its drought tolerance in most soil textures. In addition, this study supports the need for combined above- and below-ground investigations on factors influencing drought tolerance and the importance of rooting for drought resilience.
... While this indicated as a global optimum without any clusters, the gap statistics identifies a local maximum at ten clusters. We conducted our analysis towards two different ways for validation: (1) the SVC matrix was clustered into six ecotypes to quantify the proposed method with the (2) We examined higher resolved ecotypes based on the suggested ten clusters to qualitatively validate these with recent evidence of smaller-scale DNA classes ( [14,25,56], e.g.). We will discuss the results of the qualitative validation, while corresponding figures can be found in the supplementary information (SI, Qualitative validation of ten ecotypes). ...
... Assigning Douglas-fir populations in their distribution area in North America to six different response groups, ecotypes exhibit different responses characteristics to climate effects, presumably having different climate optima. Quantification of the geographic distribution of the identified ecotypes showed overlap with available large-scale DNA regions to some degree, while qualitative comparison with finer resolved and genetically analysed provenance regions implies ecotypic and genotypic similarities [14,25,56]. The results suggest that ecologically induced intra-specific variation in (unobserved) occurrencerelated traits, as well as an increased intra-variety differentiation, potentially hybrids, found in transition zones ( [57,58], p. 38) can be detected in a first screening step with a climate-based, local modelling approach to provenance outlining. ...
... Based on the genetic literature, we grouped Douglasfir populations first into six classes to quantitatively compare deduced ecotypes with available data on large-scale DNA regions [13,22,63]. Then we also grouped Douglas-fir populations into ten classes to qualitatively assess their similarities with recent smaller-scale DNA regions [14,25,56]. Clustering of the spatially-varying coefficient (SVC) matrix partly reproduced the six DNA class regions without using the DNA-data: we identified spatially well separated, latitudinally arranged, yet disjoint mainly coastal (ecotypes 1, 2 and 3) and interior ecotypes (ecotypes 4, 5, 6). ...
Background
Selection of climate-change adapted ecotypes of commercially valuable species to date relies on DNA-assisted screening followed by growth trials. For trees, such trials can take decades, hence any approach that supports focussing on a likely set of candidates may save time and money. We use a non-stationary statistical analysis with spatially varying coefficients to identify ecotypes that indicate first regions of similarly adapted varieties of Douglas-fir ( Pseudotsuga menziesii (Mirbel) Franco) in North America. For over 70,000 plot-level presence-absences, spatial differences in the survival response to climatic conditions are identified.
Results
The spatially-variable coefficient model fits the data substantially better than a stationary, i.e. constant-effect analysis (as measured by AIC to account for differences in model complexity). Also, clustering the model terms identifies several potential ecotypes that could not be derived from clustering climatic conditions itself. Comparing these six identified ecotypes to known genetically diverging regions shows some congruence, as well as some mismatches. However, comparing ecotypes among each other, we find clear differences in their climate niches.
Conclusion
While our approach is data-demanding and computationally expensive, with the increasing availability of data on species distributions this may be a useful first screening step during the search for climate-change adapted varieties. With our unsupervised learning approach being explorative, finely resolved genotypic data would be helpful to improve its quantitative validation.
... Sª de las Nieves would have maintained its effective population size in spite of the population decline. The ABC-and Migraine-based estimates for divergence times and effective population sizes should be considered a crude approximation since these algorithms do not take into account continuous migration or pollen-mediated gene flow, which counteracts differentiation, underestimating the assessed divergence and bottleneck time values (van Loo et al. 2015;Hrivnák et al. 2017). ...
A better understanding of long-term effects of climate and historical anthropogenic changes is needed to define effective conservation measures of endangered forest inhabiting managed landscapes. Diversification and distribution of Mediterranean firs are attributed to the global climate change during the Miocene and Quaternary as well as to the effects of human-driven deforestation. We evaluated the impact of climate change and anthropogenic activities in shaping the genetic diversity and structure of Abies pinsapo Boiss. (Pinaceae), a relict fir endemic from SW Spain. We genotyped a total of 440 individuals from 44 populations by using two different molecular markers (cpSSRs and nSSRs). Overall, low genetic structure was found; however, incipient differentiation appeared within mountain ranges. Analyses suggest that the effects of isolation by distance and lithological or topographical diversity were not enough to structure the populations of the different mountain ranges. The combined role of genetic drift in the small populations and the anthropogenic action associated with forest management has shaped the current genetic pattern of this fir species in the study area. Demographic inference analyses pointed to a very recent synchronic divergence (eleventh–sixteenth century) of the ancestral A. pinsapo population into its current scattered distribution range. Although population bottlenecks were supported by several analyses, the conservation of this endangered species seems not to be limited by lacking genetic diversity, while threats of current climate change and habitat loss must be regarded.
... Franco) grows naturally over a large land area across several climatic gradients with generally dry summers [1]. Within this range, it displays a high genetic variation, both quantitative and molecular [2][3][4]. Douglas fir has a long tradition as a non-native in European forestry, which dates back to the 19th century [5]. In Scandinavian countries, it has been identified as one of the most promising non-native forest trees with a high potential in a changing climate. ...
... 3 Genotypes selected in the progeny test of Danish clones. 4 Origin of individuals described in [4]. * Native seed origin partly known. ...
... 3 Genotypes selected in the progeny test of Danish clones. 4 Origin of individuals described in [4]. * Native seed origin partly known. ...
Douglas fir is expected to play an increasingly important role in Swedish forestry under a changing climate. Thus far, seed orchards with clones of phenotypically selected trees (plus trees) have been established to supply the market with highly qualitative reproductive material. Given the high genetic variation of the species, its growth properties are significantly affected by the provenance. Here, we applied microsatellite markers to identify the origin of clones selected within the Swedish breeding programme. Moreover, we analysed the timing of bud burst in open-pollinated families of these clones. In particular, we aimed to explain the provenance effect on phenology by using molecular identification as a proxy. A Bayesian clustering analysis with microsatellite data enabled the assignment of the clones to one of the two varieties and also resolved within-variety origins. The phenological observations indicated an earlier bud burst of the interior variety. Within the coastal variety, the northern provenances exhibited a later bud burst. We found a significant effect of the identified origin on bud burst timing. The results of this study will be used to support further breeding efforts.
... Thus, our review confirmed North American studies on the adaptive landscape of these conifers in relation to traits such as growth, bud burst or cold resistant (e.g., [123][124][125][126]). These adaptive landscapes can be considered a result of population history, demography (e.g., [127]) and local adaptation [128], where population differentiation can mostly be linked to climate variables (e.g., mean temperatures, coldest month temperatures, etc.) along gradients from South-to-North and West-to-East. The amount of variation explained by climate variables differs among species and subspecies [126]. ...
Citation: Alizoti, P.; Bastien, J.-C.; Chakraborty, D.; Klisz, M.M.; Kroon, J.; Neophytou, C.; Schueler, S.; van Loo, M.; Westergren, M.; Konnert, M.; et al. Non-Native Forest Tree Species in Europe: The Question of Seed Origin in Afforestation. Forests 2022, 13, 273.
... Hybridization and introgression is frequently presented in the sympatric populations of closely related species (Tsuda et al. 2017; Anamthawat-Jónsson 2019). Moreover, due to diverse population history and complex genetic and environmental interactions, some subspecies, varieties or ecotypes identified by taxonomist are in fact natural hybrids (van Loo et al. 2015;Todesco et al. 2016). In the present study, both STRUCTURE and PCoA analyses suggested a hybrid or introgressed origin of L. chinense var. ...
The population genetic structure of plants is affected by both genetic and geo-environmental factors. Dissecting the relationship between these factors is important for conservation and breeding applications of plant natural resources. Lycium chinense Mill., is a perennial shrub long-term used as both medicinal herbs and vegetables. Here we investigated the population genetic variation and structure of L. chinense (including two varieties L. chinense var. chinense and L. chinense var. potaninii Pojark. A. M. Lu) and its closely related species Lycium barbarum L. using EST-SSR markers. We found a moderate level of genetic variation presented in the L. chinense populations, which was lower than that of L. barbarum. Both STRUCTURE and PCoA analyses showed that the variety of L. chinense var. potaninii samples was potentially hybrid derived with possible donor parents of L. chinense var. chinense and L. barbarum. We also found positive relationships presented between the genetic and geographical distance, as well as between the genetic distance and annual mean temperature in populations of L. chinense and in populations only from L. chinense var. chinense, suggesting potentially isolation by distance and isolation by adaptation effects. A core collection of L. chinense that included 37 accessions was finally constructed. Hybridization and introgression has affected genetic variation of L. chinense populations. The population genetic structure of L. chinense has been driven by both hybridization and geo-environmental factors. This genetic information and core collection will facilitate the conservation and breeding of L. chinense in future.
... glauca) varieties display significant differentiation of quantitative (Eilmann et al., 2013;Chakraborty et al., 2016) and physiological traits (Zavarin and Snajberk, 1973), as well as at putatively selectively neutral (Krutovsky et al., 2009;Neophytou et al., 2016) and candidate gene loci (Müller et al., 2015). Genetic differentiation between, but also within the two varieties has been shaped both by topography and demographic history Wei et al., 2011;van Loo et al., 2015). High levels of genetic diversity can be found in areas of former glacial refugia, which hosted large populations and reside at mid-latitudes (Li and Adams, 1989;Klumpp, 1999;Krutovsky et al., 2009, Neophytou et al., 2016. ...
... Within this range, maximum genetic diversity levels have been revealed for the coastal Douglas-fir in Washington and Oregon based on allozymes (Li and Adams, 1989;Klumpp, 1999;Krutovsky et al., 2009), microsatellites (Krutovsky et al., 2009;Neophytou et al., 2016) and terpenes (Zavarin and Snajberk, 1973), and are confirmed by our study. This high genetic diversity of Douglas-fir has been attributed to the occurrence of large refugial populations that were less prone to genetic drift than small, peripheral refugia (Wei et al., 2011;van Loo et al., 2015). Large refugial populations, mainly around Willamette Valley and Puget, have been supported both by fossil evidence (Tsukada, 1982) and phylogenetic studies Wei et al., 2011). ...
Since its first introduction in the 19th century, Douglas-fir has become the economically most important non-native forest tree species in Central European countries. Many of these planted forests are important seed sources and/or exhibit natural regeneration. Thus, it is important to assess (1) the genetic diversity of the mature stands and (2) if the genetic diversity can be passed on to the next generations. In order to address these issues, we genotyped mature Douglas-fir individuals and natural regeneration from >100 native and non-native populations using nuclear microsatellite markers. We compared the genetic diversity of native North American populations with mature Douglas-fir populations in Central Europe. The results show that genetic diversity did not differ significantly between European populations and the assigned native origin. Using a subset of 36 sites from Central Europe, we detected a significant reduction in the genetic diversity of adult versus naturally regenerated juvenile trees, indicating a bottleneck effect in the next generation of European Douglas-fir stands. The main reason may be that the mature European Douglas-fir stands are highly fragmented and thus the stand size is not adequate for transmitting the genetic diversity to the next generation. This should be taken into account for the commercial harvesting of seed stands. Seed orchards may offer a potential alternative in providing high quality and genetically diverse reproductive material.
... Due to these results, several attempts were made to assign artificial Douglas-fir populations to the region of origin by comparing their genetic structure with reference populations from the natural range (Hoffmann and Geburek, 1995;Klumpp, 1999;Konnert and Ruetz, 2006;Fussi et al., 2013). The more informative nuclear microsatellite markers were applied to develop a detailed picture from the variation patterns within the natural ranges of both varieties and to enhance the regional assignments of European artificial populations (van Loo et al., 2015;Hintsteiner et al., 2018). ...
... An exception is the smallest stand Drebkau where the levels of heterozygosity decrease from the adults to the offspring sample, due to the high selfing rate derived from parentage analysis. Using similar marker sets, very similar average values for observed and expected heterozygosities were reported by Krutovsky et al. (2009) for populations within the natural range of Douglas-fir as well as by van Loo et al. (2015) and Neophytou et al. (2016) for artificial stands. Krutovsky et al. (2009) also indicated an overestimated fixation index due to false homozygote genotyping by high frequencies of null alleles. ...
Douglas-fir (Pseudotsuga menziesii), native to western North America, was introduced to Europe about 150 years ago. Nowadays it represents the most frequent non-native forest tree species in Germany, covering about 2% of the forest area. While seeds were initially imported from its natural distribution range, the German seed market is now mainly supplied with seeds from local stands. In this study we examined four representative, different sized artificial Douglas-fir stands. We used microsatellite markers to characterise adults and offspring by analysing the genetic diversity and mating system. We detected a negative correlation of population size and genetic diversity. The loss of alleles with descending population sizes cannot be compensated by pollen from outside of the stand. The results showed an increased selfing rate (1-13%) correlated with increased inbreeding effects like a high percentage of empty seeds. Diversity parameters calculated as averages across the analysed loci should always be completed with the calculation of effective population sizes considering sibship structures based on multilocus genotypes. The combined approaches are an improved basis for drawing practical conclusions. We recommend that the current regulations for forest reproductive material should be adapted. For wind-pollinated stand-forming tree species a minimum number of 100 adult trees should be required to form approved seed stands in the category "Selected".
... It is one of the main lumber species in North America, and has been introduced to many parts of the world as an exotic species. Today, there are plantations in southern Germany [3], New Zealand, Argentina, and Chile [4][5][6]. ...
The amount and structure of the genetic diversity in Mexican populations of Pseudotsuga menziesii (Mirb.) Franco, is almost unknown, since most genetic studies have been carried out on populations from Canada and the United States. Here, we applied a set of 12 microsatellite markers to 12 populations (234 trees) from the central region of Mexico in order to determine values of genetic diversity and differentiation. Seventy-three different alleles were identified: an average number of alleles per locus (Na) of 6.083, effective number of alleles (Ne) of 2.039, observed heterozygosity (Ho) of 0.229, and expected heterozygosity (Ht) of 0.417. Genetic differentiation was high: the coefficient of differentiation (θ) was 0.270, while the coefficient of structure (Φst) was 0.278. Bayesian analysis identified two genetic groups in central Mexico. The PCoA and the dendrogram were in concordance with the two genetic groups. The results of the analysis of molecular variance (AMOVA) indicate that genetic variation exists mainly within populations (72.149%). Therefore, conservation efforts should focus on as many individuals within populations as possible, to maintain this variation.
... glauca) found inland, in the mountains from British Columbia to Central Mexico (Lavender and Hermann 2014). There is no reproductive barrier between them (Gugger et al. 2010, Wei et al. 2011, van Loo et al. 2015. In Europe, a third variety, caesia, is widely recognized as an intermediate type between the coastal (viridis) and the interior (glauca) variety (Schober 1954, Aas 2008). ...
... Krutovsky et al. 2009, Fussi et al. 2013, to trace back the origin of European Douglas-fir stands (Fussi et al. 2013, Eckhart et al. 2017, Hintsteiner et al. 2018 and to analyse the mating system in Douglas-fir seed orchards (Slavov et al. 2005, Sk Lai et al. 2010, Kess and El-Kassaby 2015, Korecký and El-Kassaby 2016. 1-Amarasinghe and Carlson 2002, 2-Slavov et al. 2004, 3-Slavov et al. 2005, 4-Krutovsky et al. 2009, 5-Sk Lai et al. 2010, 6-Konnert and Fussi 2012, 7-Fussi et al. 2013, 8-Korecký and El-Kassaby 2016, 9-van Loo et al. 2015, 10-Neophytou et al. 2016, 11-Eckhart et al. 2017, 12-Hintsteiner et al. 2018 Material for DNA-extraction DNA has been extracted from needles (Neophytou et al. 2016, Fussi et al. 2013, Slavov et al. 2004, 2005, van Loo et al. 2015, Eckhart et al. 2017, Hintsteiner et al. 2018, buds (Slavov et al. 2005, Sk Lai et al. 2010, Korecký and El-Kassaby (2016, seed (embryos, megagamethophytes) (Krutovskii et al. 2009, Sk Lai et al. 2010) and cambium (Neophytou et al. 2016, van Loo et al. 2015, Eckhart et al. 2017, Hintsteiner et al. 2018). ...
... Krutovsky et al. 2009, Fussi et al. 2013, to trace back the origin of European Douglas-fir stands (Fussi et al. 2013, Eckhart et al. 2017, Hintsteiner et al. 2018 and to analyse the mating system in Douglas-fir seed orchards (Slavov et al. 2005, Sk Lai et al. 2010, Kess and El-Kassaby 2015, Korecký and El-Kassaby 2016. 1-Amarasinghe and Carlson 2002, 2-Slavov et al. 2004, 3-Slavov et al. 2005, 4-Krutovsky et al. 2009, 5-Sk Lai et al. 2010, 6-Konnert and Fussi 2012, 7-Fussi et al. 2013, 8-Korecký and El-Kassaby 2016, 9-van Loo et al. 2015, 10-Neophytou et al. 2016, 11-Eckhart et al. 2017, 12-Hintsteiner et al. 2018 Material for DNA-extraction DNA has been extracted from needles (Neophytou et al. 2016, Fussi et al. 2013, Slavov et al. 2004, 2005, van Loo et al. 2015, Eckhart et al. 2017, Hintsteiner et al. 2018, buds (Slavov et al. 2005, Sk Lai et al. 2010, Korecký and El-Kassaby (2016, seed (embryos, megagamethophytes) (Krutovskii et al. 2009, Sk Lai et al. 2010) and cambium (Neophytou et al. 2016, van Loo et al. 2015, Eckhart et al. 2017, Hintsteiner et al. 2018). ...
