Freshwater dreissenid mussels evolved from marine ancestors during the Miocene ∼30 million years ago and today include some of the most successful and destructive invasive species of freshwater environments. Here, we sequenced the genome of the quagga mussel Dreissena rostriformis to identify adaptations involved in embryonic osmoregulation. We provide evidence that a lophotrochozoan-specific aquaporin water channel, a vacuolar ATPase subunit and a sodium/hydrogen exchanger are involved in osmoregulation throughout early cleavage, during which time large intercellular fluid-filled 'cleavage cavities' repeatedly form, coalesce and collapse, expelling excess water to the exterior. Independent expansions of aquaporins coinciding with at least five freshwater colonization events confirm their role in freshwater adaptation. Repeated aquaporin expansions and the evolution of membrane-bound fluid-filled osmoregulatory structures in diverse freshwater taxa point to a fundamental principle guiding the evolution of freshwater tolerance and provide a framework for future species control efforts.

中文翻译：

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斑驳贻贝基因组和淡水耐受性的进化。

淡水德莱森贻贝在大约 3000 万年前的中新世期间从海洋祖先进化而来，今天包括一些最成功和最具破坏性的淡水环境入侵物种。在这里，我们对斑贻贝 Dreissena rostriformis 的基因组进行了测序，以确定胚胎渗透调节所涉及的适应性。我们提供的证据表明，在整个早期卵裂过程中，一个长毛虫特定的水通道蛋白水通道、一个液泡 ATP 酶亚基和一个钠/氢交换器参与渗透调节，在此期间，充满细胞间液的大“卵裂腔”反复形成、聚结和坍塌，排出体外。多余的水流到外面。与至少五次淡水定植事件同时发生的水通道蛋白的独立扩张证实了它们在淡水适应中的作用。