Estimating the effective population size and effective number of breeders per year (N_b) can facilitate early detection of population declines. We used computer simulations to quantify bias and precision of the one‐sample LDNe estimator of N_b in age‐structured populations using a range of published species life history types, sample sizes, and DNA markers. N_b estimates were biased by ~5%–10% when using SNPs or microsatellites in species ranging from fishes to mosquitoes, frogs, and seaweed. The bias (high or low) was similar for different life history types within a species suggesting that life history variation in populations will not influence N_b estimation. Precision was higher for 100 SNPs (H ≈ 0.30) than for 15 microsatellites (H ≈ 0.70). Confidence intervals (CIs) were occasionally too narrow, and biased high when N_b was small (N_b < 50); however, the magnitude of bias would unlikely influence management decisions. The CIs (from LDNe) were sufficiently narrow to achieve high statistical power (≥0.80) to reject the null hypothesis that N_b = 50 when the true N_b = 30 and when sampling 50 individuals and 200 SNPs. Similarly, CIs were sufficiently narrow to reject N_b = 500 when the true N_b = 400 and when sampling 200 individuals and 5,000 loci. Finally, we present a linear regression method that provides high power to detect a decline in N_b when sampling at least five consecutive cohorts. This study provides guidelines and tools to simulate and estimate N_b for age structured populations (https://github.com/popgengui/agestrucnb/), which should help biologists develop sensitive monitoring programmes for early detection of changes in N_b and population declines.

中文翻译：

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通过监测育种者的有效数量 (Nb ) 来检测种群下降。

估计每年的有效种群规模和有效育种者数量 ( N _b ) 有助于及早发现种群下降。我们使用一系列已发表的物种生活史类型、样本大小和 DNA 标记，使用计算机模拟来量化年龄结构种群中N _b的单样本LDNe估计量的偏差和精度。在从鱼类到蚊子、青蛙和海藻的物种中使用 SNP 或微卫星时，N _b估计值存在约 5%–10% 的偏差。一个物种内不同生活史类型的偏差（高或低）是相似的，这表明种群的生活史变化不会影响N _b估计。100 个 SNP ( H  ≈ 0.30) 的精度高于15 个微卫星 ( H  ≈ 0.70)。置信区间 (CI) 有时太窄，并且当N _b小时（N _b  < 50）偏高；然而，偏差的大小不太可能影响管理决策。顺式（从LDNe）充分缩小，以实现高功率统计（≥0.80）拒绝零假设，即Ñ _b  = 50时的真实Ñ _b  = 30和采样50分的个人和200个SNP时。类似地，顺被足够窄，以拒绝Ñ _b  = 500时的真实Ñ_b  = 400 并且当采样 200 个个体和 5,000 个基因座时。最后，我们提出了一种线性回归方法，该方法在对至少五个连续队列进行采样时提供高功效来检测N _b的下降。本研究为模拟和估计年龄结构种群的N _b (https://github.com/popgengui/agestrucnb/)提供了指导方针和工具，这将有助于生物学家开发灵敏的监测程序，以便及早发现N _b的变化和种群下降.