Technological and methodological advances have facilitated the use of genetic data to infer census population size (N_c) in natural populations, particularly where traditional mark‐and‐recapture is challenging. The effective number of breeders (N_b) describes how many adults effectively contribute to a cohort and is often correlated with N_c. Predicting N_c from N_b or vice versa in species with overlapping generations has important implications for conservation by permitting (i) estimation of the more difficult to quantify variable and (ii) inferences of N_b/N_c relationships in related species lacking data. We quantitatively synthesized N_b/N_c relationships in three salmonid fishes where sufficient data have recently accumulated. Mixed‐effects models were analysed in which each variable was included as a dependent variable or predictor term (N_b from N_c and vice versa). Species‐dependent N_b/N_c slope estimates were significantly positive in two of three species. Variation in species slopes was likely due to varying life histories and reinforce caution when inferring N_b/N_c from taxonomically related species. Models provided maximum probable estimates for N_b and N_c for two species. However, study, population and year effects explained substantial amounts of variation (39%–57%). Consequently, prediction intervals were wide and included or were close to zero for all population sizes and species; model predictive utility was limited. Cost‐benefit trade‐offs when estimating N_b and/or N_c were also discussed using a real‐world system example. Our findings based on salmonids suggest that no short cuts currently exist when estimating population size and researchers should focus on quantifying the variable of interest or be aware of caveats when inferring the desired variable because of cost or logistics. We caution that the salmonid species examined share life‐history traits that may obscure relationships between N_b and N_c. Sufficient data on other taxa were unavailable; additional research examining N_b/N_c relationships in species with potentially relevant life‐history trait differences (e.g., differing survival curves) is needed.

中文翻译：

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根据三种鱼类的遗传种群规模（或反之亦然）估计普查种群规模的关键评估。

技术和方法的进步促进了使用遗传数据来推断自然种群中的人口普查种群规模 (N _c )，特别是在传统的标记和重新捕获具有挑战性的情况下。有效繁殖者数量 (N _b ) 描述了有多少成年人有效地为一个群体做出了贡献，并且通常与 N _c相关。在世代重叠的物种中，根据N _b预测 N _c或反之亦然，对保护具有重要意义，因为它允许 (i) 估计更难以量化的变量，以及 (ii) 在缺乏数据的相关物种中推断 N _b /N _c关系。我们定量综合了三种鲑科鱼类的N _b /N _{c关系，最近积累了足够的数据。}分析了混合效应模型，其中每个变量都作为因变量或预测项（N _b来自 N _c，反之亦然）。物种相关的 N _b /N _c斜率估计在三个物种中有两个显着为正。物种斜率的变化可能是由于不同的生活史造成的，并且在从分类学相关物种推断 N _b /N _{c时要格外小心。}模型提供了两个物种的N _b和 N _c的最大可能估计值。然而，研究、人口和年份的影响解释了大量的变化（39%–57%）。因此，预测区间很宽，包括所有种群规模和物种或接近于零；模型预测效用有限。还使用实际系统示例讨论了估计 N _b和/或 N _c时的成本效益权衡。我们基于鲑鱼的研究结果表明，在估计种群规模时，目前不存在捷径，研究人员应专注于量化感兴趣的变量，或者在由于成本或物流而推断所需变量时注意注意事项。我们警告说，所检查的鲑鱼物种具有共同的生活史特征，这可能会掩盖 N _b和 N _c之间的关系。无法获得有关其他类群的足够数据；需要额外的研究来检查具有潜在相关生活史特征差异（例如不同的生存曲线）的物种中的N _b /N _c关系。