[show abstract][hide abstract] ABSTRACT: The fine-scale assessment of both spatially and non-spatially distributed genetic variation is crucial to preserve forest genetic resources through appropriate forest management. Cryptic within-population genetic structure may be more common than previously thought in forest tree populations, which has strong implications for the potential of forests to adapt to environmental change. The present study was aimed at comparing within-population genetic structure in European beech (Fagus sylvatica L.) plots experiencing different disturbance levels. Five plot pairs made up by disturbed and undisturbed plots having the same biogeographic history were sampled throughout Europe. Overall, 1298 individuals were analyzed using four highly polymorphic nuclear microsatellite markers (SSRs). Bayesian clustering within plots identified 3 to 11 genetic clusters (within-plot h ST ranged from 0.025 to 0.124). The proportion of within-population genetic variation due to genetic substructuring (F CluPlot = 0.067) was higher than the differentiation among the 10 plots (F PlotTot = 0.045). Focusing on the comparison between managed and unmanaged plots, disturbance mostly explains differences in the complexity of within-population genetic structure, determining a reduction of the number of genetic clusters present in a standardized area. Our results show that: i) genetic substructuring needs to be investigated when studying the within-population genetic structure in forest tree populations, and ii) indices describing subtle characteristics of the within-population genetic structure are good candidates for providing early signals of the consequences of forest management, and of disturbance events in general. Copyright: ß 2013 Piotti et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This study was financially supported by the European Commission through the Dynabeech project (5th Framework Programme, QLRT-1999-01210) and finalised based on the financial support by the European Commission through the FP7-project FORGER: Towards the Sustainable Management of Forest Genetic Resources in Europe (KBBE -289119). AP was supported by the Italian MIUR project ''Approccio multitaxa allo studio delle risposte della biodiversità italiana al cambiamento climatico'' (RBAP10A2T4). KK was in addition supported with co-funding by the Dutch Ministry of Economics, Agriculture and Innovation in the project (KB-14-002-033) of the Knowledge-Base Green Space and Biodiversity. This support is gratefully acknowledged. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist.
PLoS ONE 01/2013; 8(9):e73391. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Conservation priorities for Prunus africana, a tree species found across Afromontane regions, which is of great commercial interest internationally and of local value for rural communities, were defined with the aid of spatial analyses applied to a set of georeferenced molecular marker data (chloroplast and nuclear microsatellites) from 32 populations in 9 African countries. Two approaches for the selection of priority populations for conservation were used, differing in the way they optimize representation of intra-specific diversity of P. africana across a minimum number of populations. The first method (S1) was aimed at maximizing genetic diversity of the conservation units and their distinctiveness with regard to climatic conditions, the second method (S2) at optimizing representativeness of the genetic diversity found throughout the species' range. Populations in East African countries (especially Kenya and Tanzania) were found to be of great conservation value, as suggested by previous findings. These populations are complemented by those in Madagascar and Cameroon. The combination of the two methods for prioritization led to the identification of a set of 6 priority populations. The potential distribution of P. africana was then modeled based on a dataset of 1,500 georeferenced observations. This enabled an assessment of whether the priority populations identified are exposed to threats from agricultural expansion and climate change, and whether they are located within the boundaries of protected areas. The range of the species has been affected by past climate change and the modeled distribution of P. africana indicates that the species is likely to be negatively affected in future, with an expected decrease in distribution by 2050. Based on these insights, further research at the regional and national scale is recommended, in order to strengthen P. africana conservation efforts.
PLoS ONE 01/2013; 8(3):e59987. · 3.73 Impact Factor
[show abstract][hide abstract] ABSTRACT: Background and Aims Afromontane forest ecosystems share a high similarity of plant and animal biodiversity, although they occur mainly on isolated mountain massifs throughout the continent. This resemblance has long provoked questions on former wider distribution of Afromontane forests. In this study Prunus africana (one of the character trees of Afromontane forests) is used as a model for understanding the biogeography of this vegetation zone. Methods Thirty natural populations from nine African countries covering a large part of Afromontane regions were analysed using six nuclear microsatellites. Standard population genetic analysis as well as Bayesian and maximum likelihood models were used to infer genetic diversity, population differentiation, barriers to gene flow, and recent and all migration among populations. Key Results Prunus africana exhibits strong divergence among five main Afromontane regions: West Africa, East Africa west of the Eastern Rift Valley (ERV), East Africa east of the ERV, southern Africa and Madagascar. The strongest divergence was evident between Madagascar and continental Africa. Populations from West Africa showed high similarity with East African populations west of the ERV, whereas populations east of the ERV are closely related to populations of southern Africa, respectively. Conclusions The observed patterns indicate divergent population history across the continent most likely associated to Pleistocene changes in climatic conditions. The high genetic similarity between populations of West Africa with population of East Africa west of the ERV is in agreement with faunistic and floristic patterns and provides further evidence for a historical migration route. Contrasting estimates of recent and historical gene flow indicate a shift of the main barrier to gene flow from the Lake Victoria basin to the ERV, highlighting the dynamic environmental and evolutionary history of the region.
Annals of Botany 01/2013; 111(1):47-60. · 3.45 Impact Factor
[show abstract][hide abstract] ABSTRACT: Prunus africana - an evergreen tree found in Afromontane forests - is used in traditional medicine to cure benign prostate hyperplasia. Different bioactive constituents derived from bark extracts from 20 tree populations sampled throughout the species' natural range in Africa were studied by means of GC-MSD. The average concentration [mg/kgw/w] in increasing order was: lauric acid (18), myristic acid (22), n-docosanol (25), ferulic acid (49), β-sitostenone (198), β-sitosterol (490), and ursolic acid (743). The concentrations of many bark constituents were significantly correlated and concentration of n-docosanol was highly significantly correlated with all other analytes. Estimates of variance components revealed the highest variation among populations for ursolic acid (66%) and the lowest for β-sitosterol (20%). In general, environmental parameters recorded (temperature, precipitation, altitude) for the samples sites were not correlated with the concentration of most constituents; however, concentration of ferulic acid was significantly correlated with annual precipitation. Because the concentration of compounds in bark extracts may be affected by tree size, the diameter of sampled plants at 1.3m tree height (as proxy of age) was recorded. The only relationship with tree diameter was a negative correlation with ursolic acid. Under the assumption that genetically less variable populations have less variable concentrations of bark compounds, correlations between variation parameters of the concentration and the respective genetic composition based on chloroplast and nuclear DNA markers were assessed. Only variation of β-sitosterol concentration was significantly correlated with haplotypic diversity. The fixation index (F(IS)) was positively correlated with the variation in concentration of ferulic acid. Principal Components Analysis (PCA) indicated a weak geographic pattern. Mantel tests, however, revealed associations between the geographic patterns of bioactive constituents and the phylogenetic relationship among the populations sampled. This suggests an independent evolution of bark metabolism within different phylogeographical lineages, and the molecular phylogeographic pattern is partly reflected in the variation in concentration of bark constituents. The results have important implications for the design of strategies for the sustainable use and conservation of this important African tree species.
[show abstract][hide abstract] ABSTRACT: Genetic resources of forest trees are considered as a key factor for the per-sistence of forest ecosystems because the ability of tree species to survive under changing climate depends strongly on their intraspecific variation in climate response. Therefore, utilizing available genetic variation in climate response and planting alternative prove-nances suitable for future climatic conditions is considered as an important adaptation measure for forestry. On the other hand, the distribution of adaptive genetic diversity of many tree species is still unknown and the predicted shift of ecological zones and species' distribution may threaten forest genetic resources that are important for adaptation. Here, we use Norway spruce in Austria as a case study to demonstrate the genetic variation in climate response and to analyse the existing network of genetic conservation units for its effectiveness to safeguard the hotspots of adaptive and neutral genetic diversity of this species. An analysis of the climate response of 480 provenances, clustered into 9 groups of climatically similar provenances, revealed high variation among provenance groups.
Biodiversity and Conservation 06/2012; · 2.26 Impact Factor
[show abstract][hide abstract] ABSTRACT: The study of the dispersal capability of a species can provide essential information for the management and conservation of its genetic variability. Comparison of gene flow rates among populations characterized by different management and evolutionary histories allows one to decipher the role of factors such as isolation and tree density on gene movements. We used two paternity analysis approaches and different strategies to handle the possible presence of genotyping errors to obtain robust estimates of pollen flow in four European beech (Fagus sylvatica L.) populations from Austria and France. In each country one of the two plots is located in an unmanaged forest; the other plots are managed with a shelterwood system and inside a colonization area (in Austria and France, respectively). The two paternity analysis approaches provided almost identical estimates of gene flow. In general, we found high pollen immigration (~75% of pollen from outside), with the exception of the plot from a highly isolated forest remnant (~50%). In the two unmanaged plots, the average within-population pollen dispersal distances (from 80 to 184 m) were higher than previously estimated for beech. From the comparison between the Austrian managed and unmanaged plots, that are only 500 m apart, we found no evidence that either gene flow or reproductive success distributions were significantly altered by forest management. The investigated phenotypic traits (crown area, height, diameter and flowering phenology) were not significantly related with male reproductive success. Shelterwood seems to have an effect on the distribution of within-population pollen dispersal distances. In the managed plot, pollen dispersal distances were shorter, possibly because adult tree density is three-fold (163 versus 57 trees per hectare) with respect to the unmanaged one.
[show abstract][hide abstract] ABSTRACT: The colour morphs of immature female cones in European larch (Larix decidua Mill.) and Norway spruce (Picea abies (L.) Karst.) are green, red, and intermediate in colour. For the first time, these three colour morphs were studied to verify the thermoregulatory hypothesis and to investigate its underlying genetic spatial pattern. The study was based on an extensive systematic sampling, and data were analysed using principal component analysis (PCA), binary logistic regression (BLR), and spatial autocorrelation. Correlations between the nontransformed environmental variables and PC scores revealed two main ecological gradients, (i) altitude–temperate and (ii) annual precipitation. Loadings of the first two principal components exceeded 85% in both species. BLR was used to test the effect of the altitude–temperature gradient on the probability of occurrence of a specific cone colour. In both species, the occurrence of red cones was significantly positively related to high altitude with low temperatures, while green cones were significantly negatively correlated with decreasing temperature and increasing altitude. In both species the spatial pattern based on a putative Mendelian gene was nonrandom as indicated by significantly high Moran’s I values based on altitudinal distance. Spatial genetic structure was probably maintained by limited gene flow and balanced selection that maintained short-distance genetic differentiation.
Canadian Journal of Botany 03/2011; 85(2):132-140. · 1.40 Impact Factor
[show abstract][hide abstract] ABSTRACT: Scattered populations of the same tree species in montane forests through Africa have led to speculations on the origins of distributions. Here, we inferred the colonization history of the Afromontane tree Prunus africana using seven chloroplast DNA loci to study 582 individuals from 32 populations sampled in a range-wide survey from across Africa, revealing 22 haplotypes. The predominant haplotype, HT1a, occurred in 13 populations of eastern and southern Africa, while a second common haplotype, HT1m, occurred in populations of western Uganda and western Africa. The high differentiation observed between populations in East Africa was unexpected, with stands in western Uganda belonging with the western African lineage. High genetic differentiation among populations revealed using ordered alleles (N(ST) = 0.840) compared with unordered alleles (G(ST) = 0.735), indicated a clear phylogeographic pattern. Bayesian coalescence modelling suggested that 'east' and 'west' African types likely split early during southward migration of the species, while further more recent splitting events occurred among populations in the East of the continent. The high genetic similarity found between western Uganda and west African populations indicates that a former Afromontane migration corridor may have existed through Equatorial Africa.
[show abstract][hide abstract] ABSTRACT: Sal (Shorea robusta Gaertn., Dipterocarpaceae) is a wind-pollinated tropical tree species found in southern Asia. We investigated the genetic
diversity and structure at four microsatellites of 15 populations comprising continuous-peripheral and disjunct-peripheral
populations in Nepal. Estimates of genetic diversity (N
E=0.69) were similar when compared with those of other tropical tree species. A higher level of genetic diversity was observed
in continuous-peripheral populations (N
E=0.72) as compared to disjunct-peripheral (N
E=0.64). Population differentiation was higher among disjunct-peripheral populations (F
ST=0.043) than among continuous peripherals (F
ST=0.012). There was a significant association between gene flow distances and genetic differentiation (r
2=0.128, P≤0.007). No spatial arrangement of populations according to their geographical locations was found. Based on observed genetic
diversity protection of some populations in continuous-peripheral range are suggested for the sustainable conservation of
genetic resources of the species while protection of some disjunct-peripheral populations are also recommended for conserving
-Microsatellites-Genetic diversity-Peripheral populations-Nepal
[show abstract][hide abstract] ABSTRACT: Intra- and among-population variations of Juniperus seravschanica were morphologically examined in eight populations originating from elevations of 1300–2200m a.s.l. in Kyrgyzstan. Eleven traits of needles and cones were studied on 70 vouchers. In addition, height, diameter, stem form, and sex of 172 trees were recorded in the field in order to test whether male trees invest more in vegetative growth than females and if sex ratio is shaped by (limited) environmental resources. Morphological differences among populations were small, but needle length, width and thickness were statistically different. However, differences based on needle traits were independent from geographical, altitudinal and environmental distances. In sharp contrast to studies in other Juniperus species, sex ratio in J. seravschanica was strongly female biased (3.5 females : 1 male). Moreover, no correlation between the habitat conditions and the sex ratio was detected, suggesting that within the altitudinal range of this species, females occur more frequently. This has implications for sustainable use and the conservation of J. seravschanica populations. It is likely, that due to the higher investment of male individuals in vegetative growth males are more exploited than females. An average effective population size of 70% of the respective census suggests that conservation measures and non-selective logging regimes are required to allow reproduction and a natural regeneration of this species.
[show abstract][hide abstract] ABSTRACT: Picea omorika (Panč.) Purk. is a relict and an endemic species found exclusively in the Balkan, within an area of ca. 10 000 km2. Marker-based genetic diversity data in this conifer are very limited and partially contradictory. Therefore, twelve nuclear markers (ten EST-SSRs and two genomic SSRs) were tested for cross-species amplification in P. omorika. Five EST-SSRs amplified successfully and a very high number of alleles per locus was found in 50 trees originating from two natural populations (7 to 18 alleles per locus), with a total of 61 alleles. Furthermore, a high number of private alleles were detected - 13 and 14 per population, respectively. Rare alleles, i.e., alleles whose frequency was lower than 0.05, were not observed. Markers were selectively neutral, no linkage disequilibrium was detected and the genotype frequencies fitted Hardy-Weinberg proportions. Expected heterozygosity per locus ranged from 0.64 to 0.91 in both populations, with an overall mean of 0.83. Considering the small remnant population sizes of P. omorika, these values are unexpectedly high and comparable to values in P. glauca (Moench) Voss., P. sitchensis (Bong.) Carr. and P. mariana (Mill.) B.S.P. detected with an identical set of markers in samples of similar sizes.
Belgian Journal of Botany 08/2009; 142(1):89-95. · 0.63 Impact Factor
[show abstract][hide abstract] ABSTRACT: Sal (Shorea robusta) is a tree species with very good quality timber found across tropical south Asia. Due to over-exploitation, its genetic resources are highly depleted. Here we report for the first time on molecular markers in sal. Cross-species amplification of 27 Shorea microsatellites resulted in 24 of them harboring amplicons of expected sizes. Five microsatellites were moderate to highly polymorphic (N(a)=6-19). Observed and expected heterozygosities ranged from 0.49 to 0.77 and 0.52 to 0.89, respectively. These microsatellites are found to be adaptively neutral and are useful for population genetic studies in this species.
[show abstract][hide abstract] ABSTRACT: Norway spruce (Picea abies [L.] Karst.) is a broadly distributed European conifer tree whose history has been intensively studied by means of fossil records to infer the location of full-glacial refugia and the main routes of postglacial colonization. Here we use recently compiled fossil pollen data as a template to examine how past demographic events have influenced the species' modern genetic diversity. Variation was assessed in the mitochondrial nad1 gene containing two minisatellite regions. Among the 369 populations (4876 trees) assayed, 28 mitochondrial variants were identified. The patterns of population subdivision superimposed on interpolated fossil pollen distributions indicate that survival in separate refugia and postglacial colonization has led to significant structuring of genetic variation in the southern range of the species. The populations in the northern range, on the other hand, showed a shallow genetic structure consistent with the fossil pollen data, suggesting that the vast northern range was colonized from a single refugium. Although the genetic diversity decreased away from the putative refugia, there were large differences between different colonization routes. In the Alps, the diversity decreased over short distances, probably as a result of population bottlenecks caused by the presence of competing tree species. In northern Europe, the diversity was maintained across large areas, corroborating fossil pollen data in suggesting that colonization took place at high population densities. The genetic diversity increased north of the Carpathians, probably as a result of admixture of expanding populations from two separate refugia.
[show abstract][hide abstract] ABSTRACT: In this study we aimed to combine knowledge of the ecophysiology and genetics of European beech to assess the potential of this species to adapt to environmental change. Therefore, we performed field and experimental studies on the genetic and ecophysiological functioning of beech. This information was integrated through a coupled genetic–ecophysiological model for individual trees that was parameterized with information derived from our own studies or from the literature. Using the model, we evaluated the adaptive response of beech stands in two ways: firstly, through sensitivity analyses (of initial genetic diversity, pollen dispersal distance, heritability of selected phenotypic traits, and forest management, representing disturbances) and secondly, through the evaluation of the responses of phenotypic traits and their genetic diversity to four management regimes applied to 10 study plots distributed over Western Europe. The model results indicate that the interval between recruitment events strongly affects the rate of adaptive response, because selection is most severe during the early stages of forest development. Forest management regimes largely determine recruitment intervals and thereby the potential for adaptive responses. Forest management regimes also determine the number of mother trees that contribute to the next generation and thereby the genetic variation that is maintained. Consequently, undisturbed forests maintain the largest amount of genetic variation, as recruitment intervals approach the longevity of trees and many mother trees contribute to the next generation. However, undisturbed forests have the slowest adaptive response, for the same reasons.Gene flow through pollen dispersal may compensate for the loss in genetic diversity brought about by selection. The sensitivity analysis showed that the total genetic diversity of a 2 ha stand is not affected by gene flow if the pollen distance distribution is varied from highly left-skewed to almost flat. However, a stand with a prevailing short-distance gene flow has a more pronounced spatial genetic structure than stands with equal short- and long-distance gene flows. The build-up of a spatial genetic structure is also strongly determined by the recruitment interval. Overall, the modelling results indicate that European beech has high adaptive potential to environmental change if recruitment intervals are short and many mother trees contribute to the next generation.The findings have two implications for modelling studies on the impacts of climate change on forests. Firstly: it cannot be taken for granted that parameter values remain constant over a time horizon of even a few generations – this is particularly important for threshold values subject to strong selection, like budburst, frost hardiness, drought tolerance, as used in species area models. Secondly: forest management should be taken into account in future assessments, as management affects the rate of adaptive response and thereby the response on trees and forests to environmental change, and because few forests are unmanaged. We conclude that a coupled ecophysiological and quantitative genetic tree model is a useful tool for such studies.
[show abstract][hide abstract] ABSTRACT: Genetic diversity is indispensable for long-term forest sustainability and is therefore mentioned in numerous binding and nonbinding political covenants calling for action. Nevertheless, there are significant obstacles to the conservation of forest genetic resources. We discuss hindrances to genetic conservation, mainly in Europe. We identified impediments by reviewing the literature and on the basis of the experiences of the authors in this field and their participation in related political processes. The impediments include (1) difficulties in assessing and monitoring genetic erosion and human impacts (e.g., by the lack of markers showing adaptive variation and the lack of record keeping on the use and transfer of forest-tree germplasm), (2) complexities of European national structures that make the development of a common strategy toward forest genetic conservation problematic, (3) lack of effective forest governance in many parts of the world, (4) the general unattractiveness of genes as flagships in raising public awareness, (5) lack of integration of genetic aspects into biodiversity conservation, and (6) the fact that scientists and politicians are often at cross-purposes. To overcome these impediments, forest geneticists and their peers in species conservation have to participate more actively in decision making. In doing so, they must be prepared to face challenges on 2 fronts: participating in political processes and the provision of significant research findings to ensure that decisions with respect to forest genetic diversity are politically implementable and effectively address targets.
[show abstract][hide abstract] ABSTRACT: Norway spruce (Picea abies [L.] Karst.) has a pronounced ability to create different crown types embracing strongly hypotonic, epi-hypotonic, strongly amphitonic types as well as respective intermediate ones. Data of Holzer and Schultze (1987) were reanalyzed in order to identify major environmental components that may shape ecotypes and contribute to Gruber's (1989) hypothesis that phenotypic plasticity is different among different crown types. Environmental variables and crown types were assessed by Principal Components Analysis. The first principal component explained 74% of the variation that was mainly loaded by different temperature variables and altitude while the second principal component explained additional 23% mainly loaded by precipitation variables. Orientation had a statistically significant but small effect. Covariance analysis demonstrated that age had modified crown type in a way that more hypotonic types were phenotypically more variable. Overlaps between crown-type distributions were evaluated by Schoener's Index, which may range from ‘zero’ (no ecotypic overlap) to ‘one’ (complete ecotypic overlap). In the present paper this index resulted in pairwise values varying from 0.21 to 0.86. The ecotypic overlap matrix was symmetric, i.e. ecotypic pairs increased gradually with stepwise crown-type graduation. We discussed the adaptation strategy of Norway spruce based on our results and propose that adaptation in this species regarding crown architecture is mainly caused by adaptive differentiation in higher altitudes while in lower elevations phenotypic plasticity is the dominating factor.
Flora - Morphology Distribution Functional Ecology of Plants 01/2008; 203(2):126-133. · 1.72 Impact Factor
[show abstract][hide abstract] ABSTRACT: The impact of forest management on genetic diversity and mating was examined in European beech (Fagus sylvatica L.). Ten beech stands located in Europe were studied in pair-wise plots, differing in management intensity. The stands were genotyped with four highly polymorphic microsatellite loci. Comparison for genetic diversity measures between the stands with limited management and the high management-intensity stands (mostly shelter wood system) revealed no significant differences for allelic richness (A), effective number of alleles (Ae), number of rare alleles (Arare), neither for observed (Ho) nor expected heterozygosity (He). In all stands a significant excess of homozygotes was found, which is in agreement with previous isozyme publications. However, the increase in the inbreeding coefficient (Fis) in the stands with limited management was significantly higher than in the highly managed stands. Expectedly a low, but significant, differentiation among all stands was found (Fst = 0.058) which still reveals a clear geographic structure.The results indicate that the shelter wood system has no or minimum impact on the genetic diversity in European beech.
[show abstract][hide abstract] ABSTRACT: Here, palaeobotanical and genetic data for common beech (Fagus sylvatica) in Europe are used to evaluate the genetic consequences of long-term survival in refuge areas and postglacial spread. Four large datasets are presented, including over 400 fossil-pollen sites, 80 plant-macrofossil sites, and 450 and 600 modern beech populations for chloroplast and nuclear markers, respectively. The largely complementary palaeobotanical and genetic data indicate that: (i) beech survived the last glacial period in multiple refuge areas; (ii) the central European refugia were separated from the Mediterranean refugia; (iii) the Mediterranean refuges did not contribute to the colonization of central and northern Europe; (iv) some populations expanded considerably during the postglacial period, while others experienced only a limited expansion; (v) the mountain chains were not geographical barriers for beech but rather facilitated its diffusion; and (vi) the modern genetic diversity was shaped over multiple glacial-interglacial cycles. This scenario differs from many recent treatments of tree phylogeography in Europe that largely focus on the last ice age and the postglacial period to interpret genetic structure and argue that the southern peninsulas (Iberian, Italian and Balkan) were the main source areas for trees in central and northern Europe.
New Phytologist 02/2006; 171(1):199-221. · 6.74 Impact Factor