Impact of pollination environment manipulation on the apparent outcrossing rate in a Douglas-fir seed orchard

El‐Kassaby, Yousry A.; Davidson, R.

doi:10.1038/hdy.1991.7

Cited by 22 publications

(17 citation statements)

References 17 publications

(10 reference statements)

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“…Under panmixia, a selfing rate of 2% is expected to occur in this seed orchard (49/49 2 ); however, an estimate of 15.2% was detected. This value is higher than most selfing rates reported for this species' natural and/or seed orchard populations (El-Kassaby and Davidson, 1991;Ritland and El-Kassaby, 1985;Shaw and Allard, 1982;Slavov et al, 2005) and is unexpected for the following reasons: (1) pollination environment was manipulated by the bloom delay treatment which has been shown to promote outcrossing because all parents released their pollen within a limited timeframe (El-Kassaby and Davidson, 1991;El-Kassaby and Ritland, 1986;El-Kassaby et al, 1988), (2) SMP was used which also has been proven to increase outcrossing specifically if outside SMP donors were used (ElKassaby and Davidson, 1990), and (3) the seed orchard was exposed to external gene flow (see pollen contamination section below) which is expected to increase outcrossing because every successful pollen contamination event is an outcrossing event (El-Kassaby and Ritland, 1986). It could be speculated that SMP from the 12 internal parents unintentionally increased the selfing rate through application on donor clones; however, this possibility should be ruled out since pollen mixes were exclusively applied to non-pollen donors.…”

Section: Selfingcontrasting

confidence: 45%

Pollination dynamics in a Douglas-fir seed orchard as revealed by pedigree reconstruction

Lai¹,

Funda²,

Liewlaksaneeyanawin³

et al. 2010

Ann. For. Sci.

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Abstract• Pollination dynamics was studied in a Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) seed orchard using 8 nuclear microsatellite markers and pedigree reconstruction.• The seed orchard consisted of 49 parents (clones). Cone-crop management included bloom delay and supplemental mass pollination (SMP) using 12 internal and 4 external pollen donors.• A random sample of 801 bulk seeds was genotyped for both haploid megagametophyte and corresponding diploid embryo.• Using the parental population's multilocus genotypes, full pedigree reconstruction generated all the information needed to estimate the maternal, paternal, and parental reproductive success, selfing, pollen contamination, and pollination success of the 4 external pollen donors.• Maternal, paternal, and parental reproductive success varied with 80% of gametes being produced by 23, 45, and 37% of the orchard's parents, respectively, resulting in a drastically reduced effective population size as compared to the census number (14 vs. 53).• Selfing, pollen contamination, and aggregate SMP success (internal and external) were estimated to be 15.2, 10.4, and 15.0%, respectively.• Full pedigree reconstruction was effective in unraveling the orchard's pollination dynamics and both female and male reproductive success.

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Section: Selfingcontrasting

confidence: 45%

Pollination dynamics in a Douglas-fir seed orchard as revealed by pedigree reconstruction

Lai¹,

Funda²,

Liewlaksaneeyanawin³

et al. 2010

Ann. For. Sci.

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“…The Gsr value for the 49 NPs was 0.045, typical of that reported for Douglas-fir and most coniferous trees (Mouna, 1989;E1-Kassaby, 1991;Hamrick et al, 1992). The Gsr values of the domesticated populations were much lower, being 0.010, 0.013, and 0.015 for the 1GSOs before and after roguing and the 2GSOs, repectively.…”

Section: Distribution Of Variationmentioning

confidence: 83%

“…is lost, in a sample of N individuals. (Aspit et aL, 1989;Roberds et al, 1991;EI-Kassaby and Ritland, 1992;Nakamura and Wheeler, 1992), female reproductive success (EI-Kassaby et aL, 1989;Reynolds and E1-Kassaby, 1990;E1-Kassaby and Cook, 1994), as well as differences of reproductive phenology among the seed orchard parents (E1-Kassaby et al, 1988;Erickson and Adams, 1989;EI-Kassaby and Askew, 1991;Copes and Sniezko, 1991;E1-Kassaby and Davidson, 1991). These factors cause restricted mating among individuals, and thus increase the rate of random genetic drift and its effects on the depletion of the genetic variability.…”

Section: Resultsmentioning

confidence: 99%

Impact of selection and breeding on the genetic diversity in Douglas-fir

El‐Kassaby

Ritland

1996

Biodivers Conserv

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Genetic changes following domestication of Douglas-fir were studied using isozyme data derived from two generations of seed orchards and their 49 wild progenitor populations. In addition, the breeding, production, and infusion populations used in the seed orchards were compared to their wild counterparts. Several parameters of gene diversity were measured (number of alleles per locus N a, per cent of polymorphic loci PLP, and expected heterozygosity H, and population divergence D). These measures were similar or higher in the domesticated populations compared to their natural progenitors, indicating that early selection and breeding of a highly polymorphic species does not significantly reduce genetic variation. The two generations of seed orchards also did not differ, indicating that genetic variation may remain stable over future generations of forest plantations. Interestingly, compared to the natural populations, heterozygosity was higher in the seed orchards, probably due to pooling of widely distributed natural populations; however, rare localized or private alleles seemed to be less frequent in the domesticated populations. Differentiation values were not significant between the first generation orchards and the natural populations, but significant differences were observed between the second generation orchards and the wild progenitor populations, probably due to the interbreeding that forms the advanced generation seed orchards.

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“…Previous studies, however, have shown that variation in reproductive phenology has significant effects on the mating system of Douglas fir (El-Kassaby and Davidson 1991;El-Kassaby et al 1986;Erickson and Adams 1989;Sorensen 1997). Related individuals tend to have similar reproductive phenology, and thus may have a higher probability of pollinating each other than unrelated individuals, particularly if their reproductive phenology is extremely early or late.…”

Section: Predicting Inbreeding Depression Indices Of a Seed Orchard Wmentioning

confidence: 93%

Effects of inbreeding on coastal Douglas fir growth and yield in operational plantations: a model-based approach

Wang

Aitken

Woods³

et al. 2003

Theor Appl Genet

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In advanced generation seed orchards, tradeoffs exist between genetic gain obtained by selecting the best related individuals for seed orchard populations, and potential losses due to subsequent inbreeding between these individuals. Although inbreeding depression for growth rate is strong in most forest tree species at the individual tree level, the effect of a small proportion of inbreds in seed lots on final stand yield may be less important. The effects of inbreeding on wood production of mature stands cannot be assessed empirically in the short term, thus such effects were simulated for coastal Douglas fir [ Pseudotsuga menziesii var. menziesii (Mirb.) Franco] using an individual-tree growth and yield model TASS (Tree and Stand Simulator). The simulations were based on seed set, nursery culling rates, and 10-year-old field test performance for trees resulting from crosses between unrelated individuals and for inbred trees produced through mating between half-sibs, full-sibs, parents and offspring and self-pollination. Results indicate that inclusion of a small proportion of related clones in seed orchards will have relatively low impacts on stand yields due to low probability of related individuals mating, lower probability of producing acceptable seedlings from related matings than from unrelated matings, and a greater probability of competition-induced mortality for slower growing inbred individuals than for outcrossed trees. Thus, competition reduces the losses expected due to inbreeding depression at harvest, particularly on better sites with higher planting densities and longer rotations. Slightly higher breeding values for related clones than unrelated clones would offset or exceed the effects of inbreeding resulting from related matings. Concerns regarding the maintenance of genetic diversity are more likely to limit inclusion of related clones in orchards than inbreeding depression for final stand yield.

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Impact of pollination environment manipulation on the apparent outcrossing rate in a Douglas-fir seed orchard

Cited by 22 publications

References 17 publications

Pollination dynamics in a Douglas-fir seed orchard as revealed by pedigree reconstruction

Pollination dynamics in a Douglas-fir seed orchard as revealed by pedigree reconstruction

Impact of selection and breeding on the genetic diversity in Douglas-fir

Effects of inbreeding on coastal Douglas fir growth and yield in operational plantations: a model-based approach

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