Variation among clones and ortet-ramet relationship in grafted Scots pine (Pinus sylvestris L.)

In order to study the relationship between ortets and ramets (grafts) growing in the same environment or at widely different localities, clone trials were established with 20 and 45 clones, respectively, at two localities in central Sweden. The ortets selected were plus trees or trees with poor to normal growth and quality, and of considerably varying age. The characteristics studied in 1-3 years were stem dimensions; number of branches; branch length, diameter and angle; stem straightness; and cone yield. The variation among clones was studied and the components of variance estimated. The main source of variation were the site differences within each locality. The variation between clones was pronounced in most traits, particularly in cone yield, and increased with age. The repeatability in each clone was good in one test field but poor in the other. Correlations among various clone characteristics, e.g. cone production and graft habitus, have an impact on the gain to be obtained in a seed orchard. The relationships beween ortets and ramets varied but were not as close as those reported from other similar investigations with the exception of those concerning branch angles

Grundlagen und Beispiele

Hardcover, 17x24Der Einfluss des Menschen auf Waldbaumpopulationen weltweit, insbesondere in Mitteleuropa, hat sich bereits heute auf deren genetische Variation ausgewirkt. Genetische Information geht verloren, weil immer mehr Bäume von immer weniger Eltern abstammen. Einige Baumarten sind selten geworden oder in reproduktiv isolierte Populationen zerstückelt. Populationen anderer Arten wurden mit Vermehrungsgut gepflanzt, welches über ökologische Gradienten hinweg verschoben oder durch Introgression aus benachbarten Populationen ursprünglich allopatrischer Arten verändert wurde. Das Ausmaß genetischer Variation in Populationen und deren Differenzierung wird durch Parameter charakterisiert, die für die Planung von Maßnahmen der Erhaltung angemessen großer Genressourcen in situ oder ex situ unentbehrlich sind. Genetische Auswirkungen weithin angewandter forstlicher Maßnahmen einschließlich der Züchtung auf erwünschte Merkmale werden analysiert. Zum Schluss werden genetische Implikationen von Gesetzen betrachtet. In der Öffentlichkeit erfährt die Erhaltung genetischer Ressourcen derzeit leider noch wenig Aufmerksamkeit, obgleich sie das Fundament nachhaltigen Artenschutzes liefert.Man’s impact on forest tree populations worldwide and in Central Europe in particular has affected their genetic variation in the past and will continue to do so. The parental pool of tree populations is becoming smaller, causing loss of genetic information. Some tree species have become rare or fragmented into reproductively isolated populations. Populations of other species were planted from reproductive material that was shifted over ecological gradients or introgressed from neighboring populations of formerly allopatric species. The amount of genetic variation within populations and the differentiation between them is characterised by genetic parameters that are indispensable in designing measures for the conservation of gene resources of sufficient size in situ or ex situ. The genetic consequences of widely used forest operations, including the breeding of trees for desired traits, is analysed. Finally, the genetic implications of legislation are considered. Regrettably, the conservation of genetic resources currently receives little public attention, even though it provides the basis of sustainable species management

Fine-scale spatial genetic structure of sycamore maple (Acer pseudoplatanus L.)

Knowledge of SGS in plants is vital to understand the ecological and evolutionary dynamics of populations and to plan conservation strategies. Some of the major factors that can affect spatial genetic structure (SGS) in plants are the level of gene flow, spatial arrangement and life stages of individuals within populations. Applying six highly variable microsatellite markers, we investigated the effect of these factors on spatial genetic structure selecting two natural populations of sycamore maple, which is an insect-pollinated, autotetraploid and an indigenous hardwood species in Germany and in other central European countries. The two study populations had different shapes ( compact and elongated ) and tree densities. Significant SGS extended to ~180 m in the elongated population and to ~35 m in the compact population. Juvenile plants of the compact population showed significant SGS up to 40 m. Estimate of Sp statistic in high-density population was almost double of that in the population with low density. Gene dispersal distance in the low-density population was about 9 times higher than in the population with high density. The similar level of significant SGS in both adult and juvenile plants suggested minimal or no effect of life stages of individuals on SGS in the sycamore maple population. The data presented in this study can provide guidelines for seed collection and to establish populations for the conservation and management of genetic resources of the species. © 2011 The Author(s)

Modeling Population Genetic Data in Autotetraploid Species

Allozyme and PCR-based molecular markers have been widely used to investigate genetic diversity and population genetic structure in autotetraploid species. However, an empirical but inaccurate approach was often used to infer marker genotype from the pattern and intensity of gel bands. Obviously, this introduces serious errors in prediction of the marker genotypes and severely biases the data analysis. This article developed a theoretical model to characterize genetic segregation of alleles at genetic marker loci in autotetraploid populations and a novel likelihood-based method to estimate the model parameters. The model properly accounts for segregation complexities due to multiple alleles and double reduction at autotetrasomic loci in natural populations, and the method takes appropriate account of incomplete marker phenotype information with respect to genotype due to multiple-dosage allele segregation at marker loci in tetraploids. The theoretical analyses were validated by making use of a computer simulation study and their utility is demonstrated by analyzing microsatellite marker data collected from two populations of sycamore maple (Acer pseudoplatanus L.), an economically important autotetraploid tree species. Numerical analyses based on simulation data indicate that the model parameters can be adequately estimated and double reduction is detected with good power using reasonable sample size