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.普查种群数量（census population size, Nc）对于资源管理策略的制定至关重要。然而，由于有效种群数量（effective population size, Ne）与遗传随机性的短期影响及长期种群生存力密切相关，针对管理种群的有效种群数量监测工作日益增多。因此，深入了解Nc与Ne（包括种群连通性），能够为种群灭绝的种群统计风险与遗传风险提供极具价值的参考依据。本研究对加拿大西部北极地区已知5个溯河性北方花羔红点鲑（anadromous northern Dolly Varden, NDV, Salvelinus malma malma）种群中的4个开展了微卫星DNA变异分析，采用基于时间法与单样本法两种估算方式对Ne进行测算，并检验Ne与Nc之间的关联。此外，本研究运用近似贝叶斯计算（approximate Bayesian computation, ABC）评估了可能塑造该物种种群当代结构的多种进化场景，重点关注种群规模与连通性。研究结果显示，这些种群存在中等至大型的当代与历史有效种群规模，表明其短期与长期灭绝风险均较低。当代与长期Ne的估算值在种群内部及种群之间均存在差异，且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，若纳入Ne与Nc估算的误差范围，其取值区间为0.024至0.442。最后，ABC分析结果表明，NDV起源具有共同性，随后经历了隔离分化，同时维持了较大的有效种群规模，但这些种群在历史上也曾经历瓶颈事件，这大概率是冰期后拓殖过程导致的结果。上述结果印证了当前基因流有限的相关迹象，表明NDV具有独立的种群统计与进化轨迹，提示应按河流种群为单位对其进行管理。总体而言，本研究的结果进一步加深了学界对NDV的Ne、Ne/Nc以及种群统计独立性的认知，并为北极溯河性鲑科鱼类的潜在遗传与种群统计风险现状提供了全面的量化评估，同时也为未来的监测工作提供了基准基线。