Extreme environmental gradients represent excellent study systems to better understand the variables that mediate patterns of genomic variation between populations. They also allow for more accurate predictions of how future environmental change might affect marine species. The Persian/Arabian Gulf is extreme in both temperature and salinity while the adjacent Gulf of Oman has conditions more typical of tropical oceans. The sea urchin Echinometra sp. EZ inhabits both of these seas and plays a critical role in coral reef health as a grazer and bioeroder, but, to date, there have been no population genomic studies on this or any urchin species in this unique region. E. sp. EZ’s life history traits (e.g., large population sizes, large reproductive clutches, and long life spans), in theory, should homogenize populations unless non-neutral processes are occurring. Here, we generated a draft genome and a restriction-site associated DNA sequencing dataset from seven populations along an environmental gradient across the Persian/Arabian Gulf and the Gulf of Oman. The estimated genome size of E. sp. EZ was 609 Mb and the heterozygosity was amongst the highest recorded for an echinoderm at 4.5%. We recovered 918 high quality SNPs from 85 individuals which we then used in downstream analyses. Population structure analyses revealed a high degree of admixture between all sites, although there was population differentiation and significant pairwise F_ST values between the two seas. Preliminary results suggest migration is bidirectional between the seas and nine candidate loci were identified as being under putative natural selection, including one collagen gene. This study is the first to investigate the population genomics of a sea urchin from this extreme environmental gradient and is an important contribution to our understanding of the complex spatial patterns that drive genomic divergence.

中文翻译：

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海胆 Echinometra sp 的群体基因组分析。EZ 跨越极端的环境梯度。

极端环境梯度代表了优秀的研究系统，可以更好地理解介导群体之间基因组变异模式的变量。它们还可以更准确地预测未来环境变化可能如何影响海洋物种。波斯/阿拉伯湾的温度和盐度都极端，而邻近的阿曼湾则具有更典型的热带海洋条件。海胆Echinometra sp. EZ栖息在这两个海域，作为食草动物和生物侵蚀者，在珊瑚礁健康中发挥着至关重要的作用，但迄今为止，还没有针对该海胆物种或这个独特地区的任何海胆物种进行种群基因组研究。E. _ sp。从理论上讲，除非发生非中性过程，否则EZ的生活史特征（例如，种群规模大、繁殖力大、寿命长）应该会使种群同质化。在这里，我们从波斯/阿拉伯湾和阿曼湾的环境梯度上的七个种群中生成了基因组草案和限制位点相关的 DNA 测序数据集。E的估计基因组大小。sp。EZ为 609 Mb，杂合度是棘皮动物记录中最高的，为 4.5%。我们从 85 个个体中回收了 918 个高质量的 SNP，然后将其用于下游分析。种群结构分析揭示了所有地点之间的高度混合，尽管两个海洋之间存在种群分化和显着的成对F _ST值。初步结果表明，海洋之间的迁徙是双向的，并且九个候选基因座被确定为处于假定的自然选择之下，其中包括一个胶原蛋白基因。这项研究是第一个在这种极端环境梯度下研究海胆群体基因组学的研究，对于我们理解驱动基因组分歧的复杂空间模式做出了重要贡献。