Department of Ecology and Evolutionary Biology, University of Toronto, Toronto, Ontario, Canada.
AVIAN Behavioural Genomics and Physiology Group, Department of Physics, Chemistry, and Biology (IFM), Linköping University, Linköping, Sweden.
Mol Ecol. 2018 Dec;27(24):5035-5048. doi: 10.1111/mec.14942. Epub 2018 Dec 10.
Understanding the spatial scale of local adaptation and the factors associated with adaptive diversity are important objectives for ecology and evolutionary biology, and have significant implications for effective conservation and management of wild populations and natural resources. In this study, we used an environmental association analysis to identify important bioclimatic variables correlated with putatively adaptive genetic variation in a benthic marine invertebrate-the giant California sea cucumber (Parastichopus californicus)-spanning coastal British Columbia and southeastern Alaska. We used a redundancy analysis (RDA) with 3,699 single nucleotide polymorphisms (SNPs) obtained using RAD sequencing to detect candidate markers associated with 11 bioclimatic variables, including sea bottom and surface conditions, across two spatial scales (entire study area and within subregions). At the broadest scale, RDA revealed 59 candidate SNPs, 86% of which were associated with mean bottom temperature. Similar patterns were identified when population structure was accounted for. Additive polygenic scores, which provide a measure of the cumulative signal across all candidate SNPs, were strongly correlated with mean bottom temperature, consistent with spatially varying selection across a thermal gradient. At a finer scale, 23 candidate SNPs were detected, primarily associated with surface salinity (26%) and bottom current velocity (17%). Our findings suggest that environmental variables may play a role as drivers of spatially varying selection for P. californicus. These results provide context for future studies to evaluate the genetic basis of local adaptation in P. californicus and help inform the relevant scales and environmental variables for in situ field studies of putative adaptive variation in marine invertebrates.
理解局域适应的空间尺度和与适应多样性相关的因素是生态学和进化生物学的重要目标，对有效保护和管理野生种群和自然资源具有重要意义。在这项研究中，我们使用环境关联分析来确定与底栖海洋无脊椎动物——巨型加利福尼亚海参（Parastichopus californicus）——在不列颠哥伦比亚省沿海和阿拉斯加东南部的潜在适应性遗传变异相关的重要生物气候变量。我们使用冗余分析（RDA），利用 RAD 测序获得的 3699 个单核苷酸多态性（SNP），检测与 11 个生物气候变量相关的候选标记，包括海底和表面条件，跨越两个空间尺度（整个研究区域和子区域内）。在最广泛的尺度上，RDA 揭示了 59 个候选 SNP，其中 86%与平均海底温度相关。在考虑到种群结构时，也识别出了类似的模式。加性多基因评分提供了跨所有候选 SNP 的累积信号的度量，与平均海底温度高度相关，与热梯度上的空间变化选择一致。在更精细的尺度上，检测到 23 个候选 SNP，主要与表面盐度（26%）和海底海流速度（17%）相关。我们的研究结果表明，环境变量可能是加利福尼亚海参空间变化选择的驱动因素。这些结果为未来研究评估加利福尼亚海参的局域适应的遗传基础提供了背景，并有助于确定海洋无脊椎动物潜在适应性变异的原位实地研究的相关尺度和环境变量。
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