Data from: Comparative landscape genetic analysis of three Pacific salmon species from subarctic North America

We examined the assumption that landscape heterogeneity similarly influences the spatial distribution of genetic diversity in closely related and geographically overlapping species. Accordingly, we evaluated the influence of watershed affiliation and nine habitat variables from four categories (spatial isolation, habitat size, climate, and ecology) on population divergence in three species of Pacific salmon (Oncorhynchus tshawytscha, O. kisutch, and O. keta) from three contiguous watersheds in subarctic North America. By incorporating spatial data we found that the three watersheds did not form the first level of hierarchical population structure as predicted. Instead, each species exhibited a broadly similar spatial pattern: a single coastal group with populations from all watersheds and one or more inland groups primarily in the largest watershed. These results imply that the spatial scale of conservation should extend across watersheds rather than at the watershed level which is the scale for fishery management. Three independent methods of multivariate analysis identified two variables as having influence on population divergence across all watersheds: precipitation in all species and subbasin area (SBA) in Chinook. Although we found general broad-scale congruence in the spatial patterns of population divergence and evidence that precipitation may influence population divergence in each species, we also found differences in the level of population divergence (coho > Chinook and chum) and evidence that SBA may influence population divergence only in Chinook. These differences among species support a species-specific approach to evaluating and planning for the influence of broad-scale impacts such as climate change.

我们检验了如下假设：景观异质性（landscape heterogeneity）对亲缘关系相近且地理分布重叠的物种的遗传多样性空间分布具有相似影响。据此，我们评估了流域归属（watershed affiliation）以及四类（空间隔离、生境面积、气候与生态学）共九种生境变量，对北美亚北极区域三个连续流域内三种太平洋鲑（学名分别为Oncorhynchus tshawytscha、O. kisutch和O. keta）的种群分化（population divergence）的影响。通过纳入空间数据，我们发现这三个流域并未如预期般构成分层种群结构（hierarchical population structure）的第一层级。取而代之的是，每个物种均呈现出大体一致的空间格局：包含所有流域种群的单一沿海群，以及主要分布于最大流域的一个或多个内陆群。上述结果表明，保护工作的空间尺度应跨越流域范围，而非沿用当前渔业管理所采用的流域尺度。三种独立的多元分析（multivariate analysis）方法均识别出两个对所有流域种群分化具有影响的变量：所有物种均受降水量影响，而奇努克鲑则受子流域面积（subbasin area, SBA）影响。尽管我们发现种群分化的空间格局在大尺度上总体一致，且有证据表明降水量可能对每个物种的种群分化产生影响，但我们也观测到种群分化程度存在差异（银大麻哈鱼 > 奇努克鲑与狗鲑），且仅有奇努克鲑的种群分化受子流域面积影响。这些物种间的差异支持采用物种特异性方法，以评估和规划气候变化等大规模干扰的影响。