Schmalhausen Institute of Zoology , Kyiv, Ukraine.
University of St Andrews , St Andrews, Fife KY16 9TF, UK.
Proc Biol Sci. 2024 Oct;291(2032):20241106. doi: 10.1098/rspb.2024.1106. Epub 2024 Oct 9.
Cetaceans have evolved unique limb structures, such as flippers, due to genetic changes during their transition to aquatic life. However, the full understanding of the genetic and evolutionary mechanisms behind these changes is still developing. By examining 25 limb-related protein-coding genes across various mammalian species, we compared genetic changes between aquatic mammals, like whales, and other mammals with unique limb structures such as bats, rodents and elephants. Our findings revealed significant modifications in limb-related genes, including variations in the Hox, and Evx genes. Notably, a relaxed selection in several key genes was observed, suggesting a lifting of developmental constraints, which might have facilitated the emergence of morphological innovations in cetacean limb morphology. We also uncovered non-synonymous changes, insertions and deletions in these genes, particularly in the polyalanine tract of , which are distinctive to cetaceans or convergent with other aquatic mammals. These genetic variations correlated with the diverse and specialized limb structures observed in cetaceans, indicating a complex interplay of relaxed selection and specific mutations in mammalian limb evolution.
鲸类动物由于在向水生生活过渡过程中的基因变化，进化出了独特的肢体结构，如鳍状肢。然而，对于这些变化背后的遗传和进化机制的全面理解仍在不断发展。通过研究 25 种与肢体相关的蛋白编码基因在各种哺乳动物物种中的变化，我们比较了水生哺乳动物（如鲸鱼）与其他具有独特肢体结构的哺乳动物（如蝙蝠、啮齿动物和大象）之间的遗传变化。我们的研究结果揭示了与肢体相关基因的显著修饰，包括 Hox 和 Evx 基因的变异。值得注意的是，在几个关键基因中观察到选择放松，这表明发育约束的解除，这可能促进了鲸类动物肢体形态的形态创新的出现。我们还在这些基因中发现了非同义突变、插入和缺失，特别是在 Evx1 基因的多丙氨酸区，这是鲸类动物特有的，或者与其他水生哺乳动物趋同。这些遗传变异与鲸类动物观察到的多样化和特化的肢体结构相关，表明在哺乳动物肢体进化中选择放松和特定突变的复杂相互作用。
