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  • 1
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 43 (1973), S. 319-322 
    ISSN: 1432-2242
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary The effects of competition on the growth of families of loblolly pine (Pinus taeda, L.) seedlings were investigated. The experimental design made it possible to evaluate the effects of crowding on growth and to determine the types and magnitudes of intergenotypic interactions among pairs of families. The results showed that intergenotypic interactions were both highly variable and pronounced in their effect on early growth. Evidence was also found for precompetition cooperating interactions occurring among seedlings surrounded by neighbors of the same family.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 2
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 69 (1985), S. 609-615 
    ISSN: 1432-2242
    Schlagwort(e): Allozymes ; Gene flow ; Loblolly pine ; Pollen contamination ; Seed orchards
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Multilocus allozyme markers, which were present in background stands but not in two seed orchards, enabled estimation of gene flow into two seed orchards of loblolly pine. Estimates averaged 36% in two orchards over three years. When pollen pool frequencies in the background stands were used rather than gene frequencies in the non-orchard trees, the estimates averaged 60%. In one year, trees in the row on the edge of one orchard received significantly more pollen from background stands. Estimates of gene flow between the two 2-ha orchards average 10%. Implications of the observed levels of gene flow are discussed in terms of population genetics and seed orchard management.
    Materialart: Digitale Medien
    Bibliothek Standort Signatur Band/Heft/Jahr Verfügbarkeit
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  • 3
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 71 (1985), S. 201-207 
    ISSN: 1432-2242
    Schlagwort(e): Mating system ; Outcrossing ; Douglas-fir ; Shelterwood ; Isozymes
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Mating systems in two pairs of old-growth uncut and adjacent shelterwood stands of Douglas-fir (Pseudotsuga menziesii var. ‘menziesii’) were compared by estimating the proportions of viable progenies due to outcrossing (t) with both single-locus and multilocus techniques. Single-locus population estimates (ťs), ranging from 0.41 to 1.16, were significantly (P〈0.05) heterogeneous among loci in three of four stands; mean single-locus estimates for shelterwoods were not significantly different from those for uncut stands. Multilocus population estimates (ťm) ranged from 0.94 to 1.00; again, estimates for shelterwoods were not significantly different from those for uncut stands. Multilocus estimates were slightly higher than mean single-locus estimates for uncut stands but were nearly equivalent for shelterwoods, suggesting that related matings other than selfs may be associated with uncut stands, but not shelterwoods. Individual-tree outcrossing rates (ťm i), estimated for six trees in each shelterwood, ranged from 0.90 to 1.10 and were significantly heterogeneous among trees at one of the two shelterwoods. Outcrossing was high (〉 0.90) in both uncult and shelterwood stands, and no evidence indicated that low parent-tree density had affected stand outcrossing rates.
    Materialart: Digitale Medien
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  • 4
    Digitale Medien
    Digitale Medien
    Springer
    Theoretical and applied genetics 81 (1991), S. 541-550 
    ISSN: 1432-2242
    Schlagwort(e): Intergenotypic competition ; Density competition ; Genetic variance components ; Heritability
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Biologie
    Notizen: Summary Open-pollinated Douglas-fir (Pseudotsuga menziesii var ‘menziesii’ (Mirb.) Franco) families were tested in three contrasting competitive environments to test the hypothesis that relative performance as measured by total seedling dry weight is dependent upon distance or genotype of neighbors. The three competitive environmnts included (1) a mixture of individuals from all families planted at close spacing, (2) single (pure) family blocks planted at close spacing, and (3) individuals from all families planted at a wide, non-competitive spacing. Despite occasional large changes in rank between competitive environments and only moderate correlations of family means between competitive environments, the family x competitive environment interaction was non-significant. Furthermore, families did not differ significantly in competitive ability or density tolerance. The competitive environment in which seedlings were grown, however, had a large effect on estimates of variance components, which in turn led to large differences in estimates of heritability and genetic gain. Evaluation of families in mixture resulted in the largest estimates of heritability, while evaluation in pure family blocks resulted in the lowest. Analysis of correlated response to selection indicated that testing and selection in mixture result in the largest estimated gain, even if progeny of selected individuals are subsequently grown in a pure or non-competitive environment.
    Materialart: Digitale Medien
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  • 5
    Digitale Medien
    Digitale Medien
    Springer
    New forests 7 (1993), S. 319-329 
    ISSN: 1573-5095
    Schlagwort(e): emergence ; genetic diversity ; genetic gain ; nursery management ; Pseudotsuga menziesii ; seed weight
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Changes in family composition during nursery production were evaluated by following individual seeds and seedlings of 36 wind-pollinated Douglas-fir (Pseudotsuga menziesii var. menziesii (Mirb.) Franco) families sown in mixture in two operational nurseries in western Washington and Oregon. Families differed significantly in emergence and in percent of seedlings culled for being too small. However, differences were small enough that family composition was largely unaffected. The observed changes in family composition did not markedly reduce genetic diversity and did not affect the genetic gain that may be expected from an improved population. The plantable nursery stock was, for the most part, representative of the composition of families originally sown.
    Materialart: Digitale Medien
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  • 6
    Digitale Medien
    Digitale Medien
    Springer
    New forests 6 (1992), S. 217-240 
    ISSN: 1573-5095
    Schlagwort(e): gene dispersal ; mating patterns ; paternity analysis ; genetic structure
    Quelle: Springer Online Journal Archives 1860-2000
    Thema: Land- und Forstwirtschaft, Gartenbau, Fischereiwirtschaft, Hauswirtschaft
    Notizen: Abstract Patterns of gene dispersal by seeds and pollen greatly influence the genetic structure of plant populations and their effective size. This paper reviews methods of measuring gene dispersal and current information on patterns of dispersal within local populations of forest trees. Recently, a number of statistical procedures for investigating gene movement based on the use of large numbers of isozyme loci have been described. These procedures include various forms of parentage analysis and the fitting of mating models to genotypic arrays of offspring from individual maternal plants. With the levels of genetic discrimination currently possible in forest trees, the model approach appears to be the most reliable means of estimating gene dispersal parameters. Too little data are available to draw general conclusions about patterns of gene movement within natural populations. Nevertheless, reports to date indicate that dispersal by both pollen and seed can be considerable. For any one mother tree, the bulk of effective pollen in conifers may come from distant males in the same stand or from surrounding stands (gene flow). In insect-pollinated angiosperms, gene flow may also be substantial, but cross-fertilization within stands may primarily be between nearest flowering trees.
    Materialart: Digitale Medien
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