Data from: Phylogenomic analyses reveal latitudinal population structure and polymorphisms in heat stress genes in the North Atlantic snail Nucella lapillus

North Atlantic rocky intertidal species have been shaped by repeated glaciations and strong latitudinal temperature gradients, making them an excellent system to study postglacial phylogeography and thermal tolerance. Population genetics data from northwestern Atlantic species, however, often show patterns inconsistent with the prediction that high dispersal should generate weaker genetic structure among populations. Here we used next-generation sequencing restriction-associated DNA tags (RAD-seq) and a transcriptome assembled from RNA-seq data to analyze the genetic structure of northwestern Atlantic populations of the low-dispersal intertidal snail Nucella lapillus. Although previous studies in this region have detected almost no genetic structure in N. lapillus, our phylogenomic approach identified a well-supported split between northern and southern clades. By comparing RAD-seq data and our transcriptome assembly, we identified thousands of fixed single-nucleotide polymorphisms (SNPs) between these latitudinal clades that map to protein-coding genes, including genes associated with heat-stress tolerance. These fixed SNPs might represent loci under selection for different thermal regimes in the northwestern Atlantic.

北大西洋岩质潮间带物种受反复冰期与显著的纬度温度梯度共同塑造，成为研究冰期后系统生物地理学（phylogeography）与热耐受能力的绝佳研究模型。然而，西北大西洋物种的群体遗传学数据常呈现出与预期相悖的格局——即高扩散能力应会减弱种群间的遗传结构。本研究采用二代测序限制性酶切位点相关DNA标签（RAD-seq）技术，以及基于RNA-seq数据组装的转录组，对西北大西洋种群中低扩散潮间带螺类狗岩螺（Nucella lapillus）的遗传结构展开分析。尽管该区域此前的研究几乎未检测到狗岩螺存在遗传结构，但本研究的系统基因组学分析方法却鉴定出了南北两支具有高支持度的演化支（clade）分化。通过比对RAD-seq数据与本研究组装的转录组，我们在这些纬度演化支之间鉴定出了数千个固定单核苷酸多态性位点（SNPs），这些位点定位至蛋白质编码基因区域，其中包含与热应激耐受相关的基因。这些固定单核苷酸多态性位点可能代表了西北大西洋区域内适应不同温度环境的选择位点。