Data from: Multiple estimates of effective population size for monitoring a long-lived vertebrate: application to Yellowstone grizzly bears

Effective population size (Ne) is a key parameter for monitoring the genetic health of threatened populations because it reflects a population's evolutionary potential and risk of extinction due to genetic stochasticity. However, its application to wildlife monitoring has been limited because it is difficult to measure in natural populations. The isolated and well-studied population of grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem provides a rare opportunity to examine the usefulness of different Ne estimators for monitoring. We genotyped 729 Yellowstone grizzly bears using 20 microsatellites and applied three single-sample estimators to examine contemporary trends in generation interval (GI), effective number of breeders (Nb) and Ne during 1982–2007. We also used multisample methods to estimate variance (NeV) and inbreeding Ne (NeI). Single-sample estimates revealed positive trajectories, with over a fourfold increase in Ne (≈100 to 450) and near doubling of the GI (≈8 to 14) from the 1980s to 2000s. NeV (240–319) and NeI (256) were comparable with the harmonic mean single-sample Ne (213) over the time period. Reanalysing historical data, we found NeV increased from ≈80 in the 1910s–1960s to ≈280 in the contemporary population. The estimated ratio of effective to total census size (Ne/Nc) was stable and high (0.42–0.66) compared to previous brown bear studies. These results support independent demographic evidence for Yellowstone grizzly bear population growth since the 1980s. They further demonstrate how genetic monitoring of Ne can complement demographic-based monitoring of Nc and vital rates, providing a valuable tool for wildlife managers.

有效种群数量（Effective population size, Ne）是监测受威胁种群遗传健康状况的关键参数，因其可反映种群的进化潜力以及由遗传随机性引发的灭绝风险。然而，由于难以在自然种群中直接测定，该指标在野生动物监测中的应用一直受到限制。大黄石生态系统中孤立且被深入研究的灰熊（Ursus arctos）种群，为检验不同Ne估计器在监测中的实用性提供了难得的契机。本研究利用20个微卫星标记对729只黄石灰熊进行基因分型，并采用三种单样本估计器，分析了1982年至2007年间世代间隔（GI）、有效繁殖个体数（Nb）以及Ne的当代变化趋势。此外，本研究还通过多样本方法估算了方差有效种群数量（NeV）与近交有效种群数量（NeI）。单样本估计结果显示出正向变化轨迹：从1980年代至2000年代，Ne增长逾四倍（约100增至450），世代间隔近乎翻倍（约8增至14）。整个研究时段内，NeV（240~319）与NeI（256）与单样本Ne的调和均值（213）较为接近。通过重新分析历史数据，本研究发现NeV从1910年代至1960年代的约80增长至当代种群的约280。有效种群数量与总普查种群数量的比值（Ne/Nc）稳定且处于较高水平（0.42~0.66），这一结果优于此前针对棕熊的相关研究。上述结果为黄石灰熊种群自1980年代以来的增长提供了独立的遗传学证据，同时证实了对Ne的遗传监测可作为基于普查种群数量与生命率的种群统计监测的有益补充，为野生动物管理者提供了极具价值的工具。