Data from: Divergence and molecular variation in common whelk Buccinum undatum (Buccinidae) in Iceland: a trans-Atlantic comparison

The dispersal and history of species affects their genetic population structure at both small and large geographical scales. The common whelk, Buccinum undatum, is a widespread subtidal gastropod in the North Atlantic that has no planktonic larvae and has thus limited dispersal capacity. The snail, which has been harvested by humans for centuries, is highly variable in morphology. To evaluate the population structure in the rich fishing grounds in western Iceland and its divergence from samples across the Atlantic, genetic patterns based on sequence variation in two mtDNA genes (COI and 16S) and five microsatellites were studied and compared to variation in populations from both sides of the Atlantic. Significant differences in allele and haplotype frequencies were found among samples separated by short distances along the coast of Iceland. Partition of the variation showed larger variance among samples obtained from distant regions than from neighbouring sites and genetic distances were correlated with geographical distance among populations in Europe. Phylogeographic patterns in mtDNA reveal different monophyletic lineages on both sides of the Atlantic, which predate the onset of the Ice-age and which may constitute cryptic species. Similar micro- and macrogeographic patterns were observed for the mtDNA and microsatellite markers despite high frequencies of null alleles. Bayesian skyline reconstructions of the demographic history and mismatch distributions suggest that while sizes of some populations were unaffected by Ice Age glaciations others show signs of expansion after the last glacial maximum. These phylogeographic patterns are consistent with patterns expected for low dispersal species that have survived in allopatric glacial refugial populations on both sides of the Atlantic and in deep-sea refugia within each continent. The observed genetic structure has implications for conservation and sustainable management of the harvested populations.物种的扩散与演化历史会在小尺度与大尺度地理范围内影响其遗传种群结构。普通峨螺（Buccinum undatum）是北大西洋广泛分布的潮下带腹足类软体动物，不具有浮游幼虫阶段，因此扩散能力有限。该物种被人类捕捞已有数百年历史，其形态存在高度变异。为评估冰岛西部丰富渔场的种群结构，以及其与大西洋两岸采样样本的遗传分化，研究人员基于两段线粒体DNA（mtDNA）基因（COI与16S）的序列变异，以及5个微卫星（microsatellite）标记的遗传模式展开分析，并与大西洋两岸种群的遗传变异进行对比。研究发现，沿冰岛海岸短距离分隔的采样样本间，等位基因与单倍型频率存在显著差异。变异组分分析显示，远距采样样本间的遗传方差高于邻近采样点，且欧洲种群间的遗传距离与地理距离呈显著相关。线粒体DNA的系统地理格局显示，大西洋两岸存在不同的单系支系，这些支系的分化早于冰河时代的启动，可能代表隐存种（cryptic species）。尽管存在高频的无效等位基因（null alleles），但线粒体DNA与微卫星标记展现出相似的微观与宏观地理格局。贝叶斯天际线种群历史重建与错配分布分析表明，部分种群规模未受冰河冰期的影响，而另一些种群则呈现出末次冰盛期后扩张的迹象。这些系统地理格局与低扩散物种的预期模式一致：这类物种在大西洋两岸的异域冰期避难所种群，以及各大陆内部的深海避难所中存活下来。本次研究观测到的遗传结构，对该捕捞种群的保护与可持续管理具有重要启示意义。