Data from: Genetic sampling for estimating density of common species

Understanding population dynamics requires reliable estimates of population density, yet this basic information is often surprisingly difficult to obtain. With rare or difficult-to-capture species, genetic surveys from noninvasive collection of hair or scat has proved cost-efficient for estimating densities. Here, we explored whether noninvasive genetic sampling (NGS) also offers promise for sampling a relatively common species, the snowshoe hare (Lepus americanus Erxleben, 1777), in comparison with traditional live trapping. We optimized a protocol for single-session NGS sampling of hares. We compared spatial capture–recapture population estimates from live trapping to estimates derived from NGS, and assessed NGS costs. NGS provided population estimates similar to those derived from live trapping, but a higher density of sampling plots was required for NGS. The optimal NGS protocol for our study entailed deploying 160 sampling plots for 4 days and genotyping one pellet per plot. NGS laboratory costs ranged from approximately $670 to $3000 USD per field site. While live trapping does not incur laboratory costs, its field costs can be considerably higher than for NGS, especially when study sites are difficult to access. We conclude that NGS can work for common species, but that it will require field and laboratory pilot testing to develop cost-effective sampling protocols.要理解种群动态，需获取可靠的种群密度估算结果，但这类基础信息往往极难获得。针对珍稀或难以捕获的物种，通过非侵入性采集毛发或粪便样本开展的遗传调查已被证实可高效估算种群密度。本研究旨在对比传统活体诱捕法，探究非侵入性遗传采样（noninvasive genetic sampling, NGS）是否也适用于相对常见的物种——雪兔（Lepus americanus Erxleben, 1777）的采样工作。我们优化了雪兔单次采样的NGS实验方案。我们将活体诱捕法得到的空间捕获-重捕种群估算结果，与NGS得到的估算结果进行了对比，并评估了NGS的相关成本。结果显示，NGS得到的种群估算结果与活体诱捕法的结果相近，但NGS所需的采样样方密度更高。本研究中最优的NGS方案为：布设160个采样样方，采样时长4天，且每个样方仅对1份雪兔粪粒进行基因分型。每个野外站点的NGS实验室成本约为670至3000美元。尽管活体诱捕法无需承担实验室成本，但其野外成本往往远高于NGS，尤其是当研究站点难以抵达时。本研究结论表明，NGS可应用于常见物种的种群调查，但需开展野外与实验室预实验，以制定具备成本效益的采样方案。