School of Fisheries and Ocean Sciences, University of Alaska Fairbanks 17101 Point Lena Loop Road, Juneau, Alaska, 99801.
Ecol Evol. 2013 Jul;3(7):2362-77. doi: 10.1002/ece3.628. Epub 2013 Jun 13.
Low genetic divergence at neutral loci among populations is often the result of high levels of contemporary gene flow. Western Alaskan summer-run chum salmon (Oncorhynchus keta) populations demonstrate weak genetic structure, but invoking contemporary gene flow as the basis for the low divergence is problematic because salmon home to their natal streams and some of the populations are thousands of kilometers apart. We used genotypes from microsatellite and single nucleotide polymorphism loci to investigate alternative explanations for the current genetic structure of chum salmon populations from western Alaska. We also estimated current levels of gene flow among Kuskokwim River populations. Our results suggest that weak genetic structure is best explained by physical connections that occurred after the Holocene Thermal Maximum among the Yukon, Kuskokwim, and Nushagak drainages that allowed gene flow to occur among now distant populations.
在中性基因座中，种群之间的遗传分化程度较低通常是当代基因流动水平较高的结果。阿拉斯加西部的夏季洄游型红大麻哈鱼（Oncorhynchus keta）种群表现出较弱的遗传结构，但将当代基因流动作为低分化的基础是有问题的，因为鲑鱼会回到它们的出生地溪流，而有些种群则相隔数千公里。我们使用微卫星和单核苷酸多态性基因座的基因型来研究阿拉斯加西部红大麻哈鱼种群当前遗传结构的其他解释。我们还估计了克乌科克维姆河流域种群之间当前的基因流动水平。我们的研究结果表明，弱遗传结构最好通过全新世热最大值后在育空河、克乌科克维姆河和努沙格克河之间发生的物理连接来解释，这些连接允许现在遥远的种群之间发生基因流动。
