MOE Key Laboratory of Biosystems Homeostasis & Protection, State Conservation Centre for Gene Resources of Endangered Wildlife, College of Life Sciences, Zhejiang University, Hangzhou 310058, China.
Genes (Basel). 2022 Apr 12;13(4):678. doi: 10.3390/genes13040678.
Tactile-foraging birds have evolved an enlarged principal sensory nucleus (PrV) but smaller brain regions related to the visual system, which reflects the difference in sensory dependence. The "trade-off" may exist between different senses in tactile foragers, as well as between corresponding sensory-processing areas in the brain. We explored the mechanism underlying the adaptive evolution of sensory systems in three tactile foragers (kiwi, mallard, and crested ibis). The results showed that olfaction-related genes in kiwi and mallard and hearing-related genes in crested ibis were expanded, indicating they may also have sensitive olfaction or hearing, respectively. However, some genes required for visual development were positively selected or had convergent amino acid substitutions in all three tactile branches, and it seems to show the possibility of visual degradation. In addition, we may provide a new visual-degradation candidate gene who suffered dense convergent amino acid substitutions within the ZM domain. At last, two genes responsible for regulating the proliferation and differentiation of neuronal progenitor cells may play roles in determining the relative sizes of sensory areas in brain. This exploration offers insight into the relationship between specialized tactile-forging behavior and the evolution of sensory abilities and brain structures.
触觉觅食鸟类进化出了较大的主感觉核（PrV），但与视觉系统相关的脑区较小，这反映了不同感觉之间的依赖差异。触觉觅食者的不同感官之间，以及大脑中相应的感觉处理区域之间，可能存在“权衡”。我们在三种触觉觅食者（几维鸟、绿头鸭和朱鹮）中探索了感觉系统适应性进化的机制。结果表明，几维鸟和绿头鸭的嗅觉相关基因以及朱鹮的听觉相关基因都发生了扩张，这表明它们可能分别具有敏感的嗅觉或听觉。然而，一些视觉发育所必需的基因在所有三种触觉分支中都受到了正选择或发生了趋同的氨基酸替换，这似乎表明了视觉退化的可能性。此外，我们可能提供了一个新的候选视觉退化基因，该基因在 ZM 结构域内受到密集的趋同氨基酸替换。最后，两个负责调节神经元祖细胞增殖和分化的基因可能在决定大脑感觉区域的相对大小方面发挥作用。这项探索为专门的触觉觅食行为与感觉能力和大脑结构的进化之间的关系提供了新的见解。
