Data from: Assessing conservation risks to populations of an anadromous Arctic salmonid, the northern Dolly Varden (Salvelinus malma malma), via estimates of effective and census population sizes and approximate Bayesian computation

Census population size (Nc) is crucial to the development of resource management strategies, however, monitoring the effective population size (Ne) of managed populations has proliferated because of this parameter’s relationship to the short-term impacts of genetic stochasticity and long-term population viability. Thus, having a sound understanding of both Nc and Ne, including population connectivity, provides valuable insights into both the demographic and genetic risks to extinction. Here, we assessed microsatellite DNA variation in four (of five known) anadromous northern Dolly Varden (NDV, Salvelinus malma malma) populations from Canada’s western Arctic region, to estimate Ne using both temporal-based and single-sample estimators and to test for associations between Ne and Nc. We also employed approximate Bayesian computation (ABC) to evaluate several evolutionary scenarios that have potentially shaped contemporary population structure in this species, focusing particularly on population size and connectivity. We found evidence for moderate to large contemporary and historical Ne, suggesting that short- and long-term extinction risks are low for these populations. Estimates of contemporary and long-term Ne were variable within and among populations and overall estimates could not be reliably linked with Nc or available spawning habitat. The overall estimate of Ne/Nc, was 0.152 and ranged from 0.024 to 0.442 when including errors around the estimate of Ne and Nc. Finally, ABC analyses suggest that NDV had a common origin followed by divergence in isolation while maintaining large effective sizes, but also that these populations were bottlenecked in the past, likely the result of post-glacial colonization processes. These results corroborate indications of limited gene flow at present, indicating independent demographic and evolutionary trajectories that imply NDV is best managed on a per-river-population basis. Overall, the results of this study further our general understanding of Ne, Ne/Nc and demographic independence in NDV, and provide a comprehensive and quantitative assessment of the potential genetic and demographic risk status of Arctic anadromous salmonids, including baselines for future monitoring.

种群普查规模（Nc）对于资源管理策略的制定至关重要，然而由于有效种群大小（Ne）与遗传随机性的短期影响以及种群长期存续能力存在关联，针对管理种群的有效种群大小的监测研究日益增多。因此，深入了解Nc与Ne（包括种群连通性），能够为灭绝相关的种群统计风险与遗传风险提供极具价值的见解。本研究对加拿大西部北极地区已知的5个溯河洄游北部花羔红点鲑（NDV, Salvelinus malma malma）种群中的4个开展了微卫星DNA变异分析，采用基于时间序列和单样本两种估算方法来计算Ne，并检验Ne与Nc之间的关联。本研究同时运用近似贝叶斯计算（ABC）评估了可能塑造该物种种群当代结构的多种演化场景，重点关注种群规模与连通性。研究结果显示存在中等至大型的当代与历史有效种群大小，表明这些种群面临的短期与长期灭绝风险较低。当代与长期Ne的估算值在种群内部及种群间均存在差异，整体估算结果无法与Nc或现有产卵栖息地建立可靠关联。Ne/Nc的整体估算值为0.152，在纳入Ne与Nc估算的误差范围后，其取值区间为0.024至0.442。最后，ABC分析结果表明，NDV起源于共同祖先，随后经历了隔离分化，同时保持了较大的有效种群规模，但这些种群在历史上曾经历瓶颈效应，这大概率是冰期后定居过程的结果。这些结果佐证了当前基因流有限的结论，表明其种群具有独立的统计与演化轨迹，这意味着NDV应按照每条河流的种群分别进行管理。总体而言，本研究的结果进一步加深了我们对NDV中Ne、Ne/Nc以及种群统计独立性的认知，并对北极溯河洄游鲑科鱼类的潜在遗传与统计风险状况开展了全面定量评估，同时为未来的监测工作提供了基准数据。