Sitka spruce Population Study. A study in the natural variation of economic traits within an unselected population of Sitka spruce

The operational Sitka spruce selection and breeding programme commenced in 1963 with the selection in British forests of superior individuals for height, diameter, stem straightness and branching quality. Over 1800 plus-trees were selected over the next 20 years or so. Whilst these trees were thought to be of Queen Charlotte Islands origin (QCI; British Columbia, Canada) origin, forest records were often incomplete in this regard. Also there is known to be considerable variation in the performance of seed lots collected across the range of QCI. A regular programme of open-pollinated half-sib progeny testing of selected plus trees commenced in 1967.
Only if variance components are derived from an unselected population will they be free of any artificially induced bias for the selected traits and other correlated traits. A soundly based breeding strategy is dependent on reliable information regarding the underlying variation and pattern of inheritance. When accurate estimates of unbiased genetic variances are available, it is possible to make realistic predictions of times and costs likely to be incurred under different breeding schemes and selection intensities which could be simulated with mathematical models.
Ideally, a study into the variance components operating within an unselected population should be carried out prior to commencing a selection and breeding programme. This is rarely possible due to the time delay involved in obtaining data from genetic tests up to half a rotation length prior to starting a programme. At best, genetic field trials may be planned to run concurrently with the operational testing and selection programmes such that an existing programme may have its efficiency increased, or direction altered.
In 1969 there was the opportunity to collect seed from a stand of known QCI origin in which cones were being produced on all size classes of trees. 150 coning trees were randomly selected from the across the dominance classes within the stand in approximate proportion to their respective contribution to the make-up (%) of the stand. Seed extracted from the cones collected from each tree were raised as parent-specific open-pollinated families in a research nursery prior to planting out onto randomised and replicated site in spring 1972.
For more information see:
Lee, S.J., Woolliams, J., Samuel, C.J.A. and Malcolm, D.C. (2002a). A study of population variation and inheritance in Sitka spruce II. Age trends in genetic parameters for vigour traits and optimum selection ages. Silvae Genetica, 51 (2-3), 55-65
Lee, S.J., Woolliams, J., Samuel, C.J.A. and Malcolm, D.C. (2002b). A study of population variation and inheritance in Sitka spruce III. Age trends in genetic parameters and optimum selection ages for wood density, and genetic correlations with vigour traits. Silvae Genetica 51, (4), 143-151.
Lee, S.J., Woolliams, J., Samuel, C.J.A. and Malcolm, D.C. (2007). A study of population variation and inheritance in Sitka spruce IV. Correlated response in the progeny population based on selection in the parental population. Silvae Genetica 56, (1), 36-44
Samuel, C.J.A. and Johnstone, R.C.B (1979). A study of population variation and inheritance in Sitka spruce. I. Results of glasshouse, nursery and early forest progeny tests. Silvae Genetica 28(1), 26‑32. Attribution statement: Quote Forest Research as the source of the data in any publications/products.

始于1963年的西雅图云杉选育计划，旨在英国森林中挑选出在高度、直径、树干直度和分枝质量方面优异的个体。在随后的20年左右，共挑选出1800多株优质树木。尽管这些树木被认为源自夏洛特皇后群岛（QCI；加拿大不列颠哥伦比亚省），但在此方面的森林记录往往不完整。此外，已知在QCI范围内收集的种子批次在性能上存在显著差异。自1967年起，对选定的优质树木开始了定期的开放授粉半同胞后代的测试计划。只有在从未选择的种群中推导出方差成分时，这些成分才会免受对选定性状及其他相关性状的人工诱导偏差的影响。一个坚实的育种策略依赖于对潜在变异及其遗传传递模式的可靠信息。当可以获得无偏遗传方差的确切估计时，便能够对不同育种方案和选择强度下可能产生的时耗和成本做出现实预测，这些方案和强度可以通过数学模型进行模拟。理想情况下，在进行选育和育种计划之前，应开展对未选择种群内作用方差成分的研究。然而，由于获取遗传测试数据的时间延迟，这通常难以实现，遗传测试的时间长度需达到计划开始前半圈的时间。在最好的情况下，遗传田间试验可与实际测试和选育计划同步进行，以便提高现有计划的效率或改变其方向。1969年，有机会从已知为QCI起源的树群中收集种子，其中树木的球果产量涵盖了所有大小等级。从树群中随机选择了150株球果产量树，其选择比例大致与其对树群构成（%）的贡献成比例。从每株树上收集的球果中提取的种子，在春季1972年种植到随机和复制的地点之前，在研究苗圃中作为特定亲本的开放授粉家族进行培育。有关更多信息，请参阅以下文献：Lee, S.J., Woolliams, J., Samuel, C.J.A. and Malcolm, D.C. (2002a). 研究西雅图云杉种群变异和遗传传递II. 劲度性状的遗传参数的年龄趋势和最佳选择年龄。Silvae Genetica，51（2-3），55-65。Lee, S.J., Woolliams, J., Samuel, C.J.A. and Malcolm, D.C. (2002b). 研究西雅图云杉种群变异和遗传传递III. 木材密度遗传参数的年龄趋势和最佳选择年龄，以及与劲度性状的遗传相关。Silvae Genetica 51, (4), 143-151。Lee, S.J., Woolliams, J., Samuel, C.J.A. and Malcolm, D.C. (2007). 研究西雅图云杉种群变异和遗传传递IV. 基于亲本种群选择的子代种群的相关响应。Silvae Genetica 56, (1), 36-44。Samuel, C.J.A. and Johnstone, R.C.B (1979). 研究西雅图云杉种群变异和遗传传递I. 温室、苗圃和早期森林子代试验的结果。Silvae Genetica 28(1), 26-32。引用声明：在出版物/产品中引用森林研究作为数据来源。