Members of the smoothhound shark genus Mustelus display a widespread distribution pattern across ocean basins with a high degree of sub-regional endemism. The patterns and processes that resulted in smoothhound biodiversity and present-day distribution remain largely unknown. We infer the phylogenetic relationships of the genus Mustelus, based on sequence data (3474 bp) from three mitochondrial genes (CR, NADH-2 and 12S-16SrRNA) and a nuclear gene (KBTBD2) from seven species of Mustelus distributed across the eastern Atlantic- and Indo-Pacific oceans. Using the CR and KBTBD2 dataset, we infer the phylogeographic placement of Old World Mustelus, with particular reference to species from southern Africa. Using a near-complete phylogeny of the genus including Old World and New World species of Mustelus and publicly available sequences of the NADH-2 gene, we found supporting evidence indicating a major cladogenic event separating placental and aplacental species. Biogeographical analyses further revealed that the radiation of Mustelus in the southern African region was driven primarily by long-distance dispersal during the upper Miocene to lower Pleistocene. The placement of the placental blackspotted smoothhound Mustelus punctulatus at the base of the placental non-spotted clade suggests the secondary loss of black spots in the genus, and this was also supported by the ancestral state reconstruction. The results furthermore suggest that the Southern Hemisphere species of the genus arose from multiple separate dispersal events from the Northern Hemisphere which is in line with the earliest record of Mustelus in the Northern Hemisphere.

中文翻译：

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南部非洲平滑猎犬鲨（Mustelus 属）的历史生物地理学揭示了来自北半球的多次扩散事件

平滑猎犬鲨属 Mustelus 的成员在海洋盆地中表现出广泛的分布模式，具有高度的次区域特有性。导致平滑猎犬生物多样性和当今分布的模式和过程在很大程度上仍然未知。我们根据来自三个线粒体基因（CR、NADH-2 和 12S-16SrRNA）的序列数据（3474 bp）和来自分布在大西洋东部的七种鼬的核基因（KBTBD2）推断出鼬属的系统发育关系- 和印度洋 - 太平洋。使用 CR 和 KBTBD2 数据集，我们推断旧世界 Mustelus 的系统地理学位置，特别是来自南部非洲的物种。使用该属的近乎完整的系统发育，包括旧世界和新世界的 Mustelus 物种以及公开可用的 NADH-2 基因序列，我们发现了支持证据表明主要的进化事件将胎盘物种和胎盘物种分开。生物地理学分析进一步表明，非洲南部地区鼬鼠的辐射主要是由上中新世到下更新世的长距离扩散驱动的。将胎盘黑斑平滑猎犬 Mustelus punctulatus 放置在胎盘无斑进化枝的基部表明该属中的黑斑继发性丧失，这也得到了祖先状态重建的支持。