Abstract Effective Population Sizes (Ne) of three winter wheat composite cross populations (CCPs) that had been maintained under organic and conventional conditions from the F7 to the F12 were analysed. The number of plants (N) needed to maintain an Ne of 5000 for each population was calculated based on the mean variation in the number of gametes per parent S k 2 . Variability in kernel number per plant was high, leading to large variations in the contribution of single plants to the next generation. Also, N required for an Ne of 5000 individuals was somewhat variable among the CCPs, but changed little from the F7 (mean N of 11,955) to the F9 (mean N 11,854) under the assumption of 2% outcrossing. There was, however, an increase to a mean N of 14,374 between the F9 and the F12, most likely due to an extreme winterkill in the F11. The calculation of N using demographic data can only give general estimations but was well suited to show changes in the populations over time as affected by generation and year. Results show that drift was limited even under disruptive climatic events.

中文翻译：

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有机和常规种植复合杂交冬小麦种群的有效种群大小 (N) 取决于世代

摘要 分析了从 F7 到 F12 在有机和常规条件下维持的三个冬小麦复合杂交种群 (CCPs) 的有效种群大小 (Ne)。根据每个亲本 S k 2 的配子数的平均变化计算每个种群维持 5000 Ne 所需的植物数 (N)。每株籽粒数的变异性很大，导致单个植株对下一代的贡献差异很大。此外，5000 个体 Ne 所需的 N 在 CCP 之间有些变化，但在 2% 异交的假设下，从 F7（平均 N 为 11,955）到 F9（平均 N 11,854）变化不大。然而，F9 和 F12 之间的平均 N 增加到 14,374，很可能是由于 F11 中的极端冬季死亡。使用人口统计数据计算 N 只能给出一般估计，但非常适合显示受世代和年份影响的人口随时间的变化。结果表明，即使在破坏性气候事件下，漂移也是有限的。