Abstract Scorpions constitute a charismatic lineage of arthropods and comprise more than 2500 described species. Found throughout various tropical and temperate habitats, these predatory arachnids have a long evolutionary history, with a fossil record that began in the Silurian. While all scorpions are venomous, the asymmetrically diverse family Buthidae harbors nearly half the diversity of extant scorpions, and all but one of the 58 species that are medically significant to humans. However, the lack of a densely sampled scorpion phylogeny has hindered broader inferences of the diversification dynamics of scorpion toxins. To redress this gap, we assembled a phylogenomic data set of 100 scorpion venom gland transcriptomes and genomes, emphasizing the sampling of highly toxic buthid genera. To infer divergence times of venom gene families, we applied a phylogenomic node dating approach for the species tree in tandem with phylostratigraphic bracketing to estimate the minimum ages of mammal-specific toxins. Our analyses establish a robustly supported phylogeny of scorpions, particularly with regard to relationships between medically significant taxa. Analysis of venom gene families shows that mammal-active sodium channel toxins (NaTx) have independently evolved in five lineages within Buthidae. Temporal windows of mammal-targeting toxin origins are correlated with the basal diversification of major scorpion mammal predators such as shrews, bats, and rodents. These results suggest an evolutionary model of relatively recent diversification of buthid NaTx homologs in response to the diversification of scorpion predators. [Adaptation; arachnids; phylogenomic dating; phylostratigraphy; venom.]

中文翻译：

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蝎子的系统基因组学揭示了蝎子哺乳动物捕食者和哺乳动物活性钠通道毒素的同时多样化

摘要 蝎子是节肢动物的一个具有魅力的谱系，包含超过 2500 个已描述的物种。这些捕食性蛛形纲动物遍布各种热带和温带栖息地，具有悠久的进化历史，其化石记录始于志留纪。虽然所有蝎子都是有毒的，但不对称多样的布氏科拥有现存蝎子的近一半的多样性，除了对人类具有重要医学意义的 58 种蝎子中的一种以外，其他所有蝎子都是如此。然而，缺乏密集采样的蝎子系统发育阻碍了对蝎子毒素多样化动力学的更广泛推论。为了弥补这一差距，我们组装了一个包含 100 个蝎毒腺转录组和基因组的系统基因组数据集，强调了对剧毒丁香属的采样。为了推断毒液基因家族的分歧时间，我们对物种树应用了系统基因组节点测年方法，并结合植物地层括号法来估计哺乳动物特异性毒素的最小年龄。我们的分析建立了一个强有力的蝎子系统发育支持，特别是在医学上重要的分类群之间的关系方面。对毒液基因家族的分析表明，哺乳动物活性钠通道毒素 (NaTx) 在 Buthidae 的五个谱系中独立进化。哺乳动物靶向毒素来源的时间窗口与主要蝎子哺乳动物捕食者（如鼩鼱、蝙蝠和啮齿动物）的基础多样化相关。这些结果表明了一种相对较新的buthid NaTx同源物多样化的进化模型，以响应蝎子捕食者的多样化。[适应; 蛛形纲动物；系统发育约会；植物地层学；毒液。]