Amphipods of the superfamily Lysianassoidea that inhabit the hadal zone ( > 6000 m) have large bathymetric ranges and play a key role in deep ocean ecosystems. The endemism of these amphipod species makes them a good model for investigating potent natural selection and restricted dispersal in deep ocean trenches. Here, we describe genetic diversity and intraspecific population differentiation among three amphipod species from four Pacific trenches based on a mtDNA concatenated dataset (CO Ι and 16S rRNA genes) from 150 amphipod individuals. All amphipod populations had low genetic diversity, as indicated by haplotype and nucleotide diversity values. Population geographic relationship analysis of two Alicella gigantea populations revealed no genetic differentiation between these two localities (pairwise genetic differentiation coefficient = 0.00032, gene flow = 784.58), and the major variation (99.97%) was derived from variation within the populations. Historical demographic events were investigated using Tajima’s D and Fu’s F neutrality tests and analysis of mismatch distribution. Consistent results provided strong evidence to support the premise that demographic expansion occurred only for the Mariana population of Hirondellea gigas, possibly within the last 2.1–3.4 million years. These findings suggest that the formation of amphipod population structure might be the result of multiple factors including high hydrostatic pressure, food distribution, trench topographic forcing and potential ecological interactions.

中文翻译：

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太平洋地理位置分离的哈达沟中三种深海两栖类物种的遗传多样性和种群结构分析。

居住在哈达尔带（> 6000 m）的超家族Lysianassoidea的两栖类具有较大的测深范围，并在深海生态系统中起关键作用。这些两栖动物物种的特有性使其成为研究强力自然选择和在深海海沟中限制扩散的良好模型。在这里，我们基于来自150个两栖动物个体的mtDNA连接数据集（CO I和16S rRNA基因）描述了来自四个太平洋海沟的三个两栖动物物种之间的遗传多样性和种内种群分化。单倍型和核苷酸多样性值表明，所有两栖动物种群均具有较低的遗传多样性。两种大盲A的种群地理关系分析人群显示这两个地区之间没有遗传分化（成对遗传分化系数= 0.00032，基因流= 784.58），主要变异（99.97％）来自种群内的变异。使用Tajima的D和Fu的F中立性检验以及不匹配分布分析来调查历史人口事件。一致的结果提供了有力的证据来支持这一前提，即人口膨胀仅发生在Hirondellea gigas的Mariana人口上，可能是在过去的2.1–340万年内。这些发现表明，两栖动物种群结构的形成可能是多种因素的结果，包括高静水压力，食物分布，沟渠地形强迫和潜在的生态相互作用。