Variation in aboveground net primary production of diverse European Pinus sylvestris populations

On range-wide and regional scales, climate and site factors exert control over tree growth, masking the genetic basis of biomass accumulation and allocation. To determine intrinsic population differences in productivity, aboveground net primary production (ANPP) was measured in 16-year-old Scots pine from 19 geographically distinct populations grown in a common garden experiment in central Poland (52°N). The populations originated from the northern (>55°N), central (54–47°N), and southern (<45°N) European range of Scots pine. We calculated ANPP from aboveground growth components, using diameter-based allometric equations developed for this site. Average foliage, aboveground woody and total ANPP differed significantly among populations and were greater for central European populations than for the southern and northern ones. Stocking and total ANPP per tree were positively correlated to stand aboveground biomass (r ²≥0.71). The relationship between the latitude of seed origin and ANPP was curvilinear and maximum for populations originating near the planting site (52°N). ANPP declined in populations with increasing longitude eastward from the Atlantic Ocean towards the center of the continent. This study underscores the potentially large genetic control of ANPP and biomass accumulation among diverse Scots pine populations. Received: 3 January 2000 / Accepted: 29 March 2000     

Demographic history and genetic diversity in West Indian Coereba flaveola populations

The bananaquit (Coereba flaveola) has been well studied throughout the Caribbean region from a phylogenetic perspective. However, data concerning the population genetics and long-term demography of this bird species are lacking. In this study, we focused on three populations within the Lesser Antilles and one on Puerto Rico and assessed genetic and demographic processes, using five nuclear and two mitochondrial markers. We found that genetic diversity of bananaquits on Puerto Rico exceeds that on the smaller islands (Dominica, Guadeloupe and Grenada); this might reflect either successive founder events from Puerto Rico to Grenada, or more rapid drift in smaller populations subsequent to colonization. Population growth rate estimates showed no evidence of rapid expansion and migration was indicated only between populations from the closest islands of Dominica and Guadeloupe. Overall, our results suggest that a "demographic fission" model, considering only mutation and drift, but without migration, can be applied to these bananaquit populations in the West Indies.     

Low nucleotide diversity at the pal1 locus in the widely distributed Pinus sylvestris.

Nucleotide polymorphism in Scots pine (Pinus sylvestris) was studied in the gene encoding phenylalanine ammonia-lyase (Pal, EC 4.3.1.5). Scots pine, like many other pine species, has a large current population size. The observed levels of inbreeding depression suggest that Scots pine may have a high mutation rate to deleterious alleles. Many Scots pine markers such as isozymes, RFLPs, and microsatellites are highly variable. These observations suggest that the levels of nucleotide variation should be higher than those in other plant species. A 2,045-bp fragment of the pal1 locus was sequenced from five megagametophytes each from a different individual from each of four populations, from northern and southern Finland, central Russia, and northern Spain. There were 12 segregating sites in the locus. The synonymous site overall nucleotide diversity was only 0.0049. In order to compare pal1 with other pine genes, sequence was obtained from two alleles of 11 other loci (total length 4,606 bp). For these, the synonymous nucleotide diversity was 0.0056. These estimates are lower than those from other plants. This is most likely because of a low mutation rate, as estimated from between-pine species synonymous site divergence. In other respects, Scots pine has the characteristics of a species with a large effective population. There was no linkage disequilibrium even between closely linked sites. This resulted in high haplotype diversity (14 different haplotypes among 20 sequences). This could also give rise to high per locus diversity at the protein level. Divergence between populations in the main range was low, whereas an isolated Spanish population had slightly lower diversity and higher divergence than the remaining populations.     

Patterns of variation at a mitochondrial sequence-tagged-site locus provides new insights into the postglacial history of European Pinus sylvestris populations

Due to their maternal mode of inheritance, mitochondrial markers can be regarded as almost 'ideal' tools in evolutionary studies of conifer populations. In the present study, polymorphism was analysed at one mitochondrial intron (nad 1, exon B/C) in 23 native European Pinus sylvestris populations. In a preliminary screening for variation using a polymerase chain reaction-restriction fragment length polymorphism approach, two length variants were identified. By fully sequencing the 2.5 kb region, the observed length polymorphism was found to result from the insertion of a 31 bp sequence, with no other mutations observed within the intron. A set of primers was designed flanking the observed mutation, which identified a novel sequence-tagged-site mitochondrial marker for P. sylvestris. Analysis of 747 trees from the 23 populations using these primers revealed the occurrence of two distinct haplotypes in Europe. Within the Iberian Peninsula, the two haplotypes exhibited extensive population differentiation (PhiST = 0.59; P < or = 0.001) and a marked geographical structuring. In the populations of central and northern Europe, one haplotype largely predominated, with the second being found in only one individual of one population.     

Demographic history of european populations of Arabidopsis thaliana

The model plant species Arabidopsis thaliana is successful at colonizing land that has recently undergone human-mediated disturbance. To investigate the prehistoric spread of A. thaliana, we applied approximate Bayesian computation and explicit spatial modeling to 76 European accessions sequenced at 876 nuclear loci. We find evidence that a major migration wave occurred from east to west, affecting most of the sampled individuals. The longitudinal gradient appears to result from the plant having spread in Europe from the east ~10,000 years ago, with a rate of westward spread of ~0.9 km/year. This wave-of-advance model is consistent with a natural colonization from an eastern glacial refugium that overwhelmed ancient western lineages. However, the speed and time frame of the model also suggest that the migration of A. thaliana into Europe may have accompanied the spread of agriculture during the Neolithic transition.     

DNA diversity in modern East European human populations in view of demographic history and adaptation

The interaction of the human genome with the changing environment moulds the genetic structure of human populations. The variability of autosomal loci and the haplotype diversity was studied in geographically diverse populations from Russia and neighboring countries. Basic tendencies in variability were investigated concerning specific types of polymorphism. The results reveal marked differences between East European populations and those from the Asian part of Russia. The possible effects of climatic-geographic factors on the allele and haplotype frequencies have been studied for some loci. The existences of these correlations provide evidence of possible effect of both adaptation to natural environmental factors and large-scale population movements on the specificity and diversity of gene pool.     

华北地区油松种群遗传多样性分析

用酸性聚丙烯酰胺凝胶（APAGE）技术分析了华北地区5个油松种群在醇溶蛋白水平上的遗传多样性。95份材料分离出12条带,其中11条具有多态性,得到23种不同的带型。种群多态位点比例在16.67%～66.67%之间。Shannon信息指数和Nei’s指数的统计结果表明：关帝山油松种群的遗传多样性高于其它种群;华北地区油松种内遗传多样性为0.248 9;种群内的遗传多样性为0.150 7,占总变异的60.55%;种群间的遗传多样性为0.098 2,占总变异的 39.45%。     

High genetic similarity between Polish and North European Scots pine (Pinus sylvestris L.) populations at nuclear gene loci

Nucleotide polymorphisms in a set of 32 nuclear genes were studied in 19 mountain, peatbog and lowland populations of Scots pine representing known phenotypic races and populations of presumably relict character for the species in Poland. At 29 genes, the pattern of genetic variation was compared to 11 reference populations from Northern, Western and Southern Europe. Similar levels of nucleotide polymorphism and excess of low-frequency mutations were observed in Polish populations (π _tot?=?0.0055, D?=??0.308) and as compared to the reference samples (π _tot?=?0.0054, D?=??0.170). Bayesian assignment and conventional frequency-based statistics indicate that Polish populations share the same genetic background at the analysed nuclear gene markers. However, the populations showed a much closer genetic relationship with North European samples than other regional groups of populations. Across the very uniform genetic background of the populations, we identified several genes with outlier patterns of haplotype, polymorphism frequency variation and departures from compound neutrality tests. Our data indicate that the Central and North European parts of the Scots pine distribution seem particularly suitable for association genetic studies to link phenotypic and genetic variation at a large geographical scale.     

Search for nucleotide diversity patterns of local adaptation in dehydrins and other cold-related candidate genes in Scots pine (Pinus sylvestris L.)

Nucleotide variation at several cold candidate genes including seven members of the dehydrin gene family was surveyed in haplotypes of Scots pine (Pinus sylvestris) sampled in populations showing divergence for cold tolerance in Europe. Patterns of nucleotide diversity, linkage disequilibrium, and frequency spectrum of alleles were compared between north and south populations to search for signs of directional selection potentially underlying adaptation to cold. Significant differentiation between populations in allelic frequency or haplotype structure was detected at dhn1, dhn3, and abaH loci. Allelic dimorphism with no evidence of haplotype clustering by geographical distribution was found at dhn9. An excess of fixed non-synonymous mutations as compared to the outgroup P. pinaster pine species was found at dhn1. Differences in nucleotide polymorphisms were found between the members of the Kn class of dehydrin upregulated during cold acclimation (average π_sil = 0.004) as compared to the SKn class (average π_sil = 0.024). The multilocus nucleotide diversity at silent sites (θ _W = 0.009) was moderate compared to other conifer species, but higher than previous estimates for Scots pine. There was an excess of rare and high frequency derived variants as revealed by significantly negative multilocus value of Tajima’s D (D = −0.72, P < 0.01) and negative mean value of Fay and Wu H statistics (H = −0.50). The level of linkage disequilibrium decayed rapidly with an average expected r ² of 0.2 at about 200 bp. Overall, there was a positive correlation between polymorphism and divergence at ten loci when outgroup sequence was available. The discovered polymorphism will be used for further evaluation of the adaptive role of genes through association mapping studies. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

High genetic diversity at the extreme range edge: nucleotide variation at nuclear loci in Scots pine (Pinus sylvestris L.) in Scotland

Nucleotide polymorphism at 12 nuclear loci was studied in Scots pine populations across an environmental gradient in Scotland, to evaluate the impacts of demographic history and selection on genetic diversity. At eight loci, diversity patterns were compared between Scottish and continental European populations. At these loci, a similar level of diversity (θ_sil=∼0.01) was found in Scottish vs mainland European populations, contrary to expectations for recent colonization, however, less rapid decay of linkage disequilibrium was observed in the former (ρ=0.0086±0.0009, ρ=0.0245±0.0022, respectively). Scottish populations also showed a deficit of rare nucleotide variants (multi-locus Tajima''s D=0.316 vs D=−0.379) and differed significantly from mainland populations in allelic frequency and/or haplotype structure at several loci. Within Scotland, western populations showed slightly reduced nucleotide diversity (π_tot=0.0068) compared with those from the south and east (0.0079 and 0.0083, respectively) and about three times higher recombination to diversity ratio (ρ/θ=0.71 vs 0.15 and 0.18, respectively). By comparison with results from coalescent simulations, the observed allelic frequency spectrum in the western populations was compatible with a relatively recent bottleneck (0.00175 × 4N_e generations) that reduced the population to about 2% of the present size. However, heterogeneity in the allelic frequency distribution among geographical regions in Scotland suggests that subsequent admixture of populations with different demographic histories may also have played a role.     

Zinc toxicity in ectomycorrhizal Pinus sylvestris

Six strains of ectomycorrhizal fungi were compared for their ability to increase zinc tolerance in Pinus sylvestris L. seedlings. Pioneer and late-stage fungi as well as one strain collected from a Zn-polluted site were included in the study. The accumulation of zinc in the host plants was determined at two different sublethal substrate Zn concentrations. The mycobionts varied considerably in their protection of the autobionts against zinc toxicity. Several fungal species reduced zinc accumulation in the pine seedlings. A Thelephora terrestris (Ehrh.) Fr. Strain, however, increased the Zn concentration in its host plants. Specific zinc-retaining capacity of the mycelium and density of the extramatrical mycelium were important features determining the effectiveness of the zinc retention in the fungal symbiont.The experiments were carried out in a growth chamber where plants were cultivated in root observation chambers. The determination of the extent of substrate colonization showed that an elevated zinc concentration in a substrate might be an important stress factor for the growth of an ectomycorrhizal fungus. The growth of the extramatrical mycelium of some species was inhibited at the highest zinc concentration supplied. A determination of the in vitro zinc tolerance of the fungi could not always predict their tolerance as symbionts, where the latter characteristic did not determine the Zn retention capacity of their mycelium.In this paper we also discuss the possibility that on Zn-polluted soils ectomycorrhizal species and strains are selected that are Zn-tolerant and, in addition, are able to protect their own energy source, the autobiont, from toxicity. These mycorrhizal fungi act as a safety net, that can immobilize large amounts of zinc, thus preventing transport to the host plant.     

陕西子午岭林区人工油松幼树的表型多样性

为研究陕西子午岭马栏林区人工油松(Pinus tabuliformis)幼树的表型变异特征,选取种植于草地、灌木丛、白桦(Betula platyphylla)林、辽东栎(Quercus wutaishanica)林的4种人工油松幼树种群,对其针叶及枝条的表型性状进行分析。结果表明:人工油松幼树种群的7个表型性状(针叶长度、宽度、厚度、长宽比及当年生枝条的长度、基径、着生针叶数)在种群内及种群间都存在极显著差异;种群间平均表型分化系数为72.88%,大于种群内的27.12%,表明种群间变异是油松幼树表型变异的主要部分,不同种群所处的环境差异是油松幼树表型变异的主要原因;表型性状的平均变异系数为19.74%,性状离散程度居中;相关性分析表明,叶长与叶宽不相关,其他性状间均存在显著的相关关系;表型性状的聚类分析将4种人工油松幼树种群划分为3类。     

RFLP diversity and relationships among traditional European maize populations

Given the large extent of hybrid cultivation, the importance of conserving the diversity of crop genetic resources has given birth to numerous collections of old races. In the present paper, we conduct a molecular characterisation of a large collection of 488 European maize populations using the bulk RFLP analysis. The analysis of 23 RFLP loci showed a high allelic richness of 11.5 alleles per locus. Populations from eastern Europe (Poland, Austria, Germany, etc.) showed the lowest genetic diversity, a lower number of unique alleles and a higher percentage of fixed loci than populations from southern Europe. In fact, genetic diversity appeared higher in Southern regions where the first maize populations are thought to have been introduced. Molecular classification based on Rogers' distance (i.e. alleles frequencies) allowed us to distinguish three main clusters which were highly consistent with geographic origins. A Northeastern cluster grouped together early or intermediate populations from Northeastern countries and the Balkans, a southeastern cluster joined late and partially dent populations from Greece and Italy, and, a southwestern cluster was made up of early flint populations from northern Spain, Portugal and the Pyrenees. A correlation between allelic frequencies at some loci and latitude and/or longitude was observed. Such tendencies may reflect the direction of gene flow between different races of maize: for instance, North American (Northern flint) and Caribbean populations were introduced, respectively, to northern and southern Europe, in the past.     

Seed quality in hybrid swarm populations of Pinus mugo Turra and P. sylvestris L.

Crop characteristics involving cone size, average number of seeds per cone, and seed germinability have been studied for three hybrid swarm populations of Pinus mugo and P. sylvestris, two pure P. mugo populations and one pure P. sylvestris population, in northern Slovakia. Generally, reproduction capability characteristics were significantly reduced in hybrid swarms in relation to the control populations. Although there were no consistent differences between hybrid swarms and control populations in the average number of seeds per cone or cone size, seed germination rates and full seed production in hybrid swarms were lower than for the control population of P. sylvestris and one of the pure populations of P. mugo. Based on these data a conclusion has been drawn postulating partial rather than full fertility of the hybrid swarm populations of P. mugo and P. sylvestris.     

Phytotoxin Production in Bursaphelenchus xylophilus-Infected Pinus sylvestris

Our findings suggest that i) phytotoxic materials can be isolated from Bursaphelenchus xylophilus-infected Scots pine, but not from noninfected pines; ii) the phytotoxins cause wilting of 45-day-old and 2-year-old pine seedlings in a dose and species dependent manner; iii) the phytotoxins are produced early in the infection, accumulate or increase with time, and may function to suppress water transport in the tree; and iv) the phytotoxins are lipid materials of low molecular weight which are not acidic.     

Growth and nutrient characteristics in bog and fen populations of Scots pine (Pinus sylvestris)

Nutrient content in peat and growth rate, rate of nutrient accumulation and allocation patterns in Scots pine Pinus sylvestris L. from eleven natural Swedish peatlands were examined. The peatlands studied represented a wide range of climatic conditions and mire types. Whole and even-sized pines with intact root-systems were excavated to give the whole-pine budget for growth and nutrient accumulation. All samples originated from hummock communities.Pine growth and nutrient characteristics were much more variable in the minerogenous sites than in the ombrogenous sites, which indicates a larger environmental heterogeneity within the minerogenous sites. In the ombrogenous sites, rate of pine growth was constant, approximately 1 mg day^-1, and independent of latitudinal variation. There was either no relationship between latitudinal location and growth rate in the minerogenous sites, which suggests that pine growth is largely controlled by site-specific, very local conditions. The growth rate of pines was not correlated with any peat nutrient. The pines allocated a large proportion of their nutrient-pool to the metabolically active current year's growth. This is likely a trait that enables Scots pine to occupy a wide range of peatland types in which it experience a marked imbalance and shortage of nutrients.     

Intraspecific responses to climate in Pinus sylvestris

Abstract Five population-specific response functions were developed from quadratic models for 110 populations of Pinus sylvestris growing at 47 planting sites in Eurasia and North America. The functions predict 13 year height from climate: degree-days > 5 °C; mean annual temperature; degree-days < 0 °C; summer-winter temperature differential; and a moisture index, the ratio of degree-days > 5 °C to mean annual precipitation. Validation of the response functions with two sets of independent data produced for all functions statistically significant simple correlations with coefficients as high as 0.81 between actual and predicted heights. The response functions described the widely different growth potentials typical of natural populations and demonstrated that these growth potentials have different climatic optima. Populations nonetheless tend to inhabit climates colder than their optima, with the disparity between the optimal and inhabited climates becoming greater as the climate becomes more severe. When driven by a global warming scenario of the Hadley Center, the functions described short-term physiologic and long-term evolutionary effects that were geographically complex. The short-term effects should be negative in the warmest climates but strongly positive in the coldest. Long-term effects eventually should ameliorate the negative short-term impacts, enhance the positive, and in time, substantially increase productivity throughout most of the contemporary pine forests of Eurasia. Realizing the long-term gains will require redistribution of genotypes across the landscape, a process that should take up to 13 generations and therefore many years.     

Hybridization and genetic variation in Danish populations of European crab apple (Malus sylvestris)

The aim of the present study was to investigate the genetic variation in Danish populations of the endangered European crab apple (Malus sylvestris). Special emphasis was given to hybridization between the wild species and its cultivated relative Malus ×domestica. A total of 178 wild individuals from four Danish populations were studied along with a reference sample of 29 old cultivars. The genetic variation within and among samples was studied at ten microsatellite marker loci. Additionally, a morphological analysis was carried out to identify hybrids and test for correspondence between phenotypic and genotypic indices of hybridization. From application of ordination and a model-based cluster analysis to the molecular data, two clusters were identified consisting of wild and cultivated individuals, respectively. This indicates that pronounced admixture between the two species is not present. At the population level, a high correspondence was found between geographic isolation from M. ×domestica and genotypic and morphological indices of hybridization. As expected, isolated populations appeared less affected by hybridization than poorly isolated populations. Isolated “pure” M. sylvestris populations could thus be identified. However, morphological and molecular evidences of hybridization were found to be divergent at the individual level. This is suggestive of some historical introgression into the M. sylvestris gene pool and indicates that relying exclusively on either morphological or molecular characters as diagnostic markers in studies of hybridization between M. ×domestica and M. sylvestris might lead to fallible results. Combined application of genetic and morphological markers is therefore recommended.     

Nutrient cycling in Pinus sylvestris stands in eastern Finland

Nutrient cycling within three Pinus sylvestris stands was studied in eastern Finland. The aim of the study was to determine annual fluxes and distribution of N, P, K, Ca, Mg, Zn, Fe, B, and Al in the research stands. Special emphasis was put on determining the importance of different fluxes, especially the internal cycle within the trees in satisfying the tree nutrient requirements for biomass production. The following nutrient fluxes were included, input; free precipitation and throughfall, output; percolation through soil profile, biological cycle; nutrient uptake from soil, retranslocation within trees, return to soil in litterfall, release by litter decomposition. The distribution of nutrients was determined in above- and belowground tree compartments, in ground and field vegetation, and in soil.The nitrogen use efficiencies were 181, 211 and 191 g of tree aboveground dry matter produced per g of N supplied by uptake and retranslocation in the sapling, pole stage and mature stands, respectively. Field vegetation was more efficient in nitrogen use than trees. Stand belowground/aboveground and fine root/coarse root biomass ratios decreased with tree age. With only slightly higher fine root biomass, almost three times more nitrogen had to be taken-up from soil for biomass production in the mature stand than in the sapling stand.The annual input-output balances of most nutrients were positive; throughfall contained more nutrients than was lost in mineral soil leachate. The sulphate flux contributed to the leaching of cations, especially magnesium, from soil in the mature stand.Retranslocation supplied 17–42% of the annual N, P and K requirements for tree aboveground biomass production. Precipitation and throughfall were important in transferring K and Mg, and also N in the sapling stand. Litterfall was an important pathway for N, Ca, Mg and micro nutrients, especially in the oldest stands.     

Demographic history of Canary Islands male gene-pool: replacement of native lineages by European

Background  

The origin and prevalence of the prehispanic settlers of the Canary Islands has attracted great multidisciplinary interest. However, direct ancient DNA genetic studies on indigenous and historical 17^th–18^th century remains, using mitochondrial DNA as a female marker, have only recently been possible. In the present work, the analysis of Y-chromosome polymorphisms in the same samples, has shed light on the way the European colonization affected male and female Canary Island indigenous genetic pools, from the conquest to present-day times.