Data from: Trpc2 Pseudogenization dynamics in bats reveal ancestral vomeronasal signaling, then pervasive loss

Comparative methods are often used to infer loss or gain of complex phenotypes, but few studies take advantage of genes tightly linked with complex traits to test for shifts in the strength of selection. In mammals vomerolfaction detects chemical cues mediating many social and reproductive behaviors and is highly conserved, but all bats exhibit degraded vomeronasal structures with the exception of two families (Phyllostomidae and Miniopteridae). These families either regained vomerolfaction after ancestral loss, or there were many independent losses after diversification from an ancestor with functional vomerolfaction. In this study, we use the Transient receptor potential cation channel 2 (Trpc2) as a molecular marker for testing the evolutionary mechanisms of loss and gain of the mammalian vomeronasal system. We sequenced Trpc2 exon 2 in over 100 bat species across 17 of 20 chiropteran families. Most families showed independent pseudogenizing mutations in Trpc2, but the reading frame was highly conserved in phyllostomids and miniopterids. Phylogeny-based simulations suggest loss of function occurred after bat families diverged, and purifying selection in two families has persisted since bats shared a common ancestor. As most bats still display pheromone-mediated behavior, they might detect pheromones through the main olfactory system without using the Trpc2 signaling mechanism.比较研究方法常被用于推断复杂表型的得失，但鲜有研究借助与复杂性状紧密连锁的基因，来检测选择强度的变化。在哺乳动物中，犁鼻嗅觉（vomerolfaction）可检测介导诸多社会与生殖行为的化学信号，且该通路高度保守；但除叶口蝠科（Phyllostomidae）和长翼蝠科（Miniopteridae）外，所有蝙蝠均存在犁鼻结构退化的现象。这些类群要么是在祖先丢失犁鼻嗅觉后重新获得了该功能，要么是在从具有功能性犁鼻嗅觉的共同祖先分化后，经历了多次独立的丢失事件。本研究以瞬时受体电位阳离子通道2（Trpc2）作为分子标记，探究哺乳动物犁鼻系统得失演化的分子机制。我们对翼手目（Chiroptera）20个科中的17个科、共100余种蝙蝠的Trpc2外显子2进行了测序。多数类群的Trpc2均存在独立的假基因化突变，但叶口蝠科与长翼蝠科的阅读框仍高度保守。基于系统发育的模拟分析显示，功能丧失事件发生在蝙蝠各科分化之后，而两个类群的纯化选择自蝙蝠拥有共同祖先以来便持续存在。鉴于多数蝙蝠仍保留信息素介导的行为，它们可能无需借助Trpc2信号通路，而是通过主嗅觉系统来检测信息素。