PDF(Pubmed)
Abstract：
In mammalian research, it has been debated what can initiate an evolutionary tradeoff between different senses, and the phenomenon of sensory tradeoff in rodents, the most abundant mammalian clade, is not evident. The Nile rat (Arvicanthis niloticus), a murid rodent, recently adapted to a diurnal niche through an evolutionary acquisition of daylight vision with enhanced visual acuity. As such, this model provides an opportunity for a cross-species investigation where comparative morphological and multi-omic analyses of the Nile rat are made with its closely related nocturnal species, e.g. the mouse (Mus musculus) and the rat (Rattus norvegicus). Thus, morphological examinations were performed, and evolutionary reductions in relative sizes of turbinal bone surfaces, the cribriform plate, and the olfactory bulb were discovered in Nile rats. Subsequently, we compared multiple murid genomes, and profiled olfactory epithelium transcriptomes of mice and Nile rats at various ages with RNA sequencing. The results further demonstrate that, in comparison with mouse olfactory receptor (OR) genes, Nile rat OR genes have experienced less frequent gain, more frequent loss, and more frequent expression reduction during their evolution. Furthermore, functional degeneration of coding sequences in the Nile rat lineage was found in OR genes, yet not in other genes. Taken together, these results suggest that acquisition of improved vision in the Nile rat has been accompanied by degeneration of both olfaction-related anatomical structures and OR gene repertoires, consistent with the hypothesis of an olfaction-vision tradeoff initiated by the switch from a nocturnal to a diurnal lifestyle in mammals.
摘要：
在哺乳动物研究中，人们一直在争论什么可以引发不同感官之间的进化权衡，以及啮齿动物的感官权衡现象，最丰富的哺乳动物进化枝，不明显。尼罗河鼠（Arvicanthisniloticus），一只鼠类,最近通过进化获取日光视力以增强视敏度来适应昼夜生态位。因此，该模型为跨物种调查提供了机会，在该研究中，尼罗河大鼠的形态学和多体分析与夜间密切相关的物种进行了比较，例如，小鼠（Musmusculus）和大鼠（Rattusnorvegicus）。因此，进行形态学检查，和进化减少的相对大小的鼻甲骨表面，筛板，在尼罗河大鼠中发现了嗅球。随后，我们比较了多个类群基因组，并对不同年龄的小鼠和尼罗河大鼠的嗅觉上皮转录组进行RNA测序（RNA-seq）。结果进一步证明,与小鼠嗅觉受体（OR）基因相比，尼罗河鼠OR基因经历了较少频率的增益，更频繁的损失，以及在其进化过程中更频繁的表达减少。此外，在OR基因中发现了尼罗河大鼠谱系中编码序列的功能退化，但没有其他基因。一起来看,这些结果表明，尼罗河大鼠视力改善的获得伴随着嗅觉相关解剖结构和OR基因库的退化，与哺乳动物从夜间生活方式转变为昼夜生活方式所引发的嗅觉-视觉权衡的假设一致。
