Racicot Kelsey J, Popic Christina, Cunha Felipe, Wright Dominic, Henriksen Rie, Iwaniuk Andrew N
Department of Neuroscience, University of Lethbridge, Lethbridge, Alberta, Canada T1K3M4.
AVIAN Behavioural Genomics and Physiology Group, IFM Biology, Linköping University, Linköping 58183, Sweden.
R Soc Open Sci. 2021 Oct 13;8(10):211002. doi: 10.1098/rsos.211002. eCollection 2021 Oct.
Domestication is the process by which wild organisms become adapted for human use. Many phenotypic changes are associated with animal domestication, including decreases in brain and brain region sizes. In contrast with this general pattern, the chicken has a larger cerebellum compared with the wild red junglefowl, but what neuroanatomical changes are responsible for this difference have yet to be investigated. Here, we quantified cell layer volumes, neuron numbers and neuron sizes in the cerebella of chickens and junglefowl. Chickens have larger, more folded cerebella with more and larger granule cells than junglefowl, but neuron numbers and cerebellar folding were proportional to cerebellum size. However, chickens do have relatively larger granule cell layer volumes and relatively larger granule cells than junglefowl. Thus, the chicken cerebellum can be considered a scaled-up version of the junglefowl cerebellum, but with enlarged granule cells. The combination of scaling neuron number and disproportionate enlargement of cell bodies partially supports a recent theory that domestication does not affect neuronal density within brain regions. Whether the neuroanatomical changes we observed are typical of domestication or not requires similar quantitative analyses in other domesticated species and across multiple brain regions.
驯化是野生生物适应人类利用的过程。许多表型变化与动物驯化相关，包括大脑及脑区尺寸的减小。与这一普遍模式相反，家鸡的小脑比野生原鸡的更大，但造成这种差异的神经解剖学变化尚未得到研究。在此，我们对家鸡和原鸡小脑的细胞层体积、神经元数量及神经元大小进行了量化。家鸡的小脑更大，褶皱更多，与原鸡相比有更多且更大的颗粒细胞，但神经元数量和小脑褶皱与小脑大小成正比。然而，家鸡的颗粒细胞层体积相对更大，颗粒细胞也相对更大。因此，家鸡的小脑可被视为原鸡小脑的放大版，但颗粒细胞有所增大。神经元数量按比例缩放与细胞体不成比例增大相结合，部分支持了一种近期理论，即驯化并不影响脑区内的神经元密度。我们观察到的神经解剖学变化是否为驯化的典型特征，需要在其他驯化物种及多个脑区进行类似的定量分析。
