Department of Environmental Life Sciences Graduate Program, Trent University, Peterborough, ON, Canada.
Department of Biology, Acadia University, Wolfville, NS, Canada.
Genome Biol Evol. 2024 Nov 1;16(11). doi: 10.1093/gbe/evae225.
Originating 30 million years ago, shrews (Soricidae) have diversified into around 400 species worldwide. Shrews display a wide array of adaptations, with some species having developed distinctive traits such as echolocation, underwater diving, and venomous saliva. Accordingly, these tiny insectivores are ideal to study the genomic mechanisms of evolution and adaptation. We conducted a comparative genomic analysis of four shrew species and 16 other mammals to identify genomic variations unique to shrews. Using two existing shrew genomes and two de novo assemblies for the maritime (Sorex maritimensis) and smoky (Sorex fumeus) shrews, we identified mutations in conserved regions of the genomes, also known as accelerated regions, gene families that underwent significant expansion, and positively selected genes. Our analyses unveiled shrew-specific genomic variants in genes associated with the nervous, metabolic, and auditory systems, which can be linked to unique traits in shrews. Notably, genes suggested to be under convergent evolution in echolocating mammals exhibited accelerated regions in shrews, and pathways linked to putative body size plasticity were detected. These findings provide insight into the evolutionary mechanisms shaping shrew species, shedding light on their adaptation and divergence over time.
起源于 3000 万年前，鼩鼱（鼩形目）已经在全球范围内分化为约 400 种。鼩鼱表现出各种各样的适应性，有些物种已经发展出独特的特征，如回声定位、水下潜水和有毒唾液。因此，这些微小的食虫动物是研究进化和适应的基因组机制的理想选择。我们对四种鼩鼱物种和 16 种其他哺乳动物进行了比较基因组分析，以鉴定鼩鼱特有的基因组变异。我们使用现有的两个鼩鼱基因组和两个海洋（Sorex maritimensis）和烟雾（Sorex fumeus）鼩鼱的从头组装，鉴定了基因组保守区域（也称为加速区域）、基因家族发生显著扩张以及阳性选择基因的突变。我们的分析揭示了与神经系统、代谢和听觉系统相关的基因中的鼩鼱特异性基因组变异，这些变异可能与鼩鼱的独特特征有关。值得注意的是，在回声定位哺乳动物中被认为是趋同进化的基因在鼩鼱中表现出加速区域，并且检测到与潜在体型可塑性相关的途径。这些发现为塑造鼩鼱物种的进化机制提供了深入了解，揭示了它们随着时间的推移的适应和分化。
