Data from: Genomics and telemetry suggest a role for migration harshness in determining overwintering habitat choice, but not gene flow, in anadromous Arctic Char

Migration is a ubiquitous life history trait with profound evolutionary and ecological consequences. Recent developments in telemetry and genomics, when combined, can bring significant insights on the migratory ecology of non-model organisms in the wild. Here, we used this integrative approach to document dispersal, gene flow and potential for local adaptation in anadromous Arctic Char from six rivers in the Canadian Arctic. Acoustic telemetry data from 124 tracked individuals indicated asymmetric dispersal, with a large proportion of fish (72%) tagged in three different rivers migrating up the same short river in the fall. Population genomics data from 6,136 SNP markers revealed weak, albeit significant, population differentiation (average pairwise FST = 0.011) and asymmetric dispersal was also revealed by population assignments. Approximate Bayesian Computation simulations suggested the presence of asymmetric gene flow, although in the opposite direction to that observed from the telemetry data, suggesting that dispersal does not necessarily lead to gene flow. These observations suggested that Arctic Char home to their natal river to spawn, but may overwinter in rivers with the shortest migratory route to minimize the costs of migration in non-breeding years. Genome scans and genetic-environment associations identified 90 outlier markers putatively under selection, 23 of which were in or near a gene. Of these, at least four were involved in muscle and cardiac function, consistent with the hypothesis that migratory harshness could drive local adaptation. Our study illustrates the power of integrating genomics and telemetry to study migrations in non-model organisms in logistically challenging environments such as the Arctic.

洄游（Migration）是一类广泛存在的生物生活史性状，可产生深远的进化与生态效应。近年来，遥测技术（telemetry）与基因组学的结合，能够为野生非模式生物（non-model organisms）的洄游生态学研究提供关键洞见。本研究采用这一整合研究策略，对加拿大北极地区六条河流中的溯河产卵北极红点鲑（anadromous Arctic Char）的扩散行为、基因流及局部适应潜力进行了系统记录。
针对124尾被追踪个体的声学遥测（acoustic telemetry）数据显示，该种群存在不对称扩散行为：在三条不同河流中标记的个体中，有72%会在秋季逆流洄游至同一条较短的河流中。基于6136个单核苷酸多态性（SNP）标记的种群基因组学数据表明，尽管种群分化程度较弱但具有统计学显著性（平均成对FST值为0.011）；种群归属分析同样揭示了不对称扩散现象。近似贝叶斯计算（Approximate Bayesian Computation）模拟结果显示，种群存在不对称基因流，但其方向与遥测数据观测到的扩散方向相反，这表明扩散行为未必会引发基因流。
上述观测结果提示，北极红点鲑会返回其出生河流进行产卵，但在非繁殖年份可能会选择拥有最短洄游路径的河流越冬，以降低迁徙过程中的能量成本。基因组扫描与遗传-环境关联分析共鉴定出90个候选受选择异常标记位点，其中23个位于基因内部或基因邻近区域。其中至少有4个位点与肌肉和心脏功能相关，这与“洄游过程中的严酷环境压力可推动局部适应”的假说相符。本研究证实了将基因组学与遥测技术相结合，可在北极这类后勤保障受限的环境中开展非模式生物的洄游行为研究。