The Viviparidae, commonly known as River Snails, is a dominant group of freshwater snails with a nearly worldwide distribution that reaches its highest taxonomic and morphological diversity in Southeast Asia. The rich fossil record is indicative of a probable Middle Jurassic origin on the Laurasian supercontinent where the group started to diversify during the Cretaceous. However, it remains uncertain when and how the biodiversity hotspot in Southeast Asia was formed. Here, we used a comprehensive genetic dataset containing both mitochondrial and nuclear markers and comprising species representing 24 out of 28 genera from throughout the range of the family. To reconstruct the spatiotemporal evolution of viviparids on a global scale, we reconstructed a fossil-calibrated phylogeny. We further assessed the roles of cladogenetic and anagenetic events in range evolution. Finally, we reconstructed the evolution of shell features by estimating ancestral character states to assess whether the appearance of sculptured shell morphologies was driven by major habitat shifts. The molecular phylogeny supports the monophyly of the three subfamilies, the Bellamyinae, Lioplacinae, and Viviparinae, but challenges the currently accepted genus-level classification in several cases. The almost global distribution of River Snails has been influenced both by comparatively ancient vicariance and more recent founder events. In Southeast Asia, Miocene dispersal was a main factor in shaping the modern species distributions. A recurrent theme across different viviparid taxa is that many species living in lentic waters exhibit sculptured shells, whereas only one strongly sculptured species is known from lotic environments. We show that such shell sculpture is habitat-dependent and indeed evolved several times independently in lentic River Snails. Considerably high transition rates between shell types in lentic habitats probably caused the co-occurrence of morphologically distinct shell types in several lakes. In contrast, directional evolution towards smooth shells in lotic habitats, as identified in the present analyses, explains why sculptured shells are rarely found in these habitats. However, the specific factors that promoted changes in shell morphology require further work.

中文翻译：

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自侏罗纪以来的全球多样化动态：低扩散和栖息地依赖性进化解释了河螺（蜗牛科）多样性和壳差异的热点

Viviparidae，通常被称为河蜗牛，是淡水蜗牛的主要群体，几乎遍布全球，在东南亚达到了最高的分类学和形态多样性。丰富的化石记录表明劳亚斯超大陆可能起源于中侏罗纪，该群体在白垩纪开始多样化。然而，东南亚的生物多样性热点何时以及如何形成仍不确定。在这里，我们使用了一个包含线粒体和核标记的综合遗传数据集，包括代表整个家族范围内 28 个属中的 24 个的物种。为了在全球范围内重建胎生动物的时空演化，我们重建了化石校准的系统发育。我们进一步评估了进化枝和遗传事件在范围进化中的作用。最后，我们通过估计祖先特征状态来重建贝壳特征的演变，以评估雕刻贝壳形态的出现是否是由主要栖息地变化驱动的。分子系统发育支持三个亚科的单系，Bellamyinae、Lioplacinae 和 Viviparinae，但在一些情况下挑战了目前接受的属级分类。River Snails 的几乎全球分布受到了相对古老的替代事件和最近的创始人事件的影响。在东南亚，中新世的扩散是塑造现代物种分布的主要因素。不同胎生动物分类群的一个反复出现的主题是，生活在静水水域的许多物种都展示了雕刻的贝壳，而在激流环境中只知道一种强烈雕刻的物种。我们表明，这种贝壳雕塑依赖于栖息地，并且确实在稳定的河蜗牛中独立进化了几次。缓慢栖息地中贝壳类型之间相当高的转换率可能导致在几个湖泊中同时出现形态不同的贝壳类型。相比之下，如本分析所确定的，在激流栖息地中向光滑贝壳的定向进化解释了为什么在这些栖息地中很少发现雕刻的贝壳。然而，促进壳形态变化的具体因素需要进一步研究。缓慢栖息地中贝壳类型之间相当高的转换率可能导致在几个湖泊中同时出现形态不同的贝壳类型。相比之下，如本分析所确定的，在激流栖息地中向光滑贝壳的定向进化解释了为什么在这些栖息地中很少发现雕刻的贝壳。然而，促进壳形态变化的具体因素需要进一步研究。缓慢栖息地中贝壳类型之间相当高的转换率可能导致在几个湖泊中同时出现形态不同的贝壳类型。相比之下，如本分析所确定的，在激流栖息地中向光滑贝壳的定向进化解释了为什么在这些栖息地中很少发现雕刻的贝壳。然而，促进壳形态变化的具体因素需要进一步研究。