The transition to an aquatic lifestyle in cetaceans (whales and dolphins) resulted in a radical transformation in their sensory systems. Toothed whales acquired specialized high-frequency hearing tied to the evolution of echolocation, whereas baleen whales evolved low-frequency hearing. More generally, all cetaceans show adaptations for hearing and seeing underwater. To determine the extent to which these phenotypic changes have been driven by molecular adaptation, we performed large-scale targeted sequence capture of 179 sensory genes across the Cetacea, incorporating up to 54 cetacean species from all major clades as well as their closest relatives, the hippopotamuses. We screened for positive selection in 167 loci related to vision and hearing and found that the diversification of cetaceans has been accompanied by pervasive molecular adaptations in both sets of genes, including several loci implicated in nonsyndromic hearing loss. Despite these findings, however, we found no direct evidence of positive selection at the base of odontocetes coinciding with the origin of echolocation, as found in studies examining fewer taxa. By using contingency tables incorporating taxon- and gene-based controls, we show that, although numbers of positively selected hearing and nonsyndromic hearing loss genes are disproportionately high in cetaceans, counts of vision genes do not differ significantly from expected values. Alongside these adaptive changes, we find increased evidence of pseudogenization of genes involved in cone-mediated vision in mysticetes and deep-diving odontocetes.

中文翻译：

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鲸类动物视觉和听觉基因中的阳性选择和失活。

鲸类（鲸鱼和海豚）向水生生活方式的过渡导致其感觉系统发生了根本性转变。齿鲸获得了与回声定位的发展相关的专业高频听力，而鲸鱼则进化出低频听力。更一般而言，所有鲸类动物都表现出适应水下听和见的能力。为了确定这些表型变化受分子适应性驱动的程度，我们对整个鲸类中的179个感官基因进行了大规模靶向序列捕获，纳入了来自所有主要进化枝及其近亲的54种鲸类物种。河马。我们筛选了与视觉和听觉有关的167个基因座中的阳性选择，发现鲸蜡类动物的多样化伴随着这两种基因中普遍的分子适应性变化，包括与非综合征性听力损失有关的几个基因座。尽管有这些发现，但是，正如在研究较少类群的研究中发现的那样，我们没有发现直接的证据表明在正牙菌的基部正选择是与回声定位的起源相吻合的。通过使用结合基于分类群和基因的对照的列联表，我们显示，尽管在鲸类动物中阳性选择的听力和非综合征性听力损失基因的数量不成比例地高，但视觉基因的数量与预期值没有显着差异。除了这些适应性变化，