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值，但这类基础信息的获取往往出人意料地困难。对于珍稀或难以捕获的物种，通过无创采集毛发或粪便开展的遗传调查已被证实可高效低成本地估算种群密度。本研究旨在对比传统活捕法，探究无创遗传采样（noninvasive genetic sampling, NGS）是否也适用于采样较为常见的物种——雪兔（*Lepus americanus* Erxleben, 1777）。我们优化了单次采样的雪兔无创遗传采样方案。我们对比了活捕法与无创遗传采样得到的空间捕获-重捕种群估算结果，并评估了无创遗传采样的成本。无创遗传采样得到的种群估算结果与活捕法所得结果相近，但无创遗传采样需要更高密度的采样样地。本研究中最优的无创遗传采样方案为：布设160个采样样地，持续4天，每个样地对1团粪便进行基因分型。每个野外样地的无创遗传采样实验室成本约为670至3000美元。尽管活捕法无需承担实验室成本，但其野外成本却远高于无创遗传采样，尤其是在野外样地难以抵达的情况下。本研究结论表明，无创遗传采样可适用于常见物种，但需开展野外与实验室预实验，以制定兼具成本效益的采样方案。