Meeting Abstract
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. Although the effects of domestication on the brain have been investigated across a range of species, almost nothing is known about chicken (Gallus gallus d.) brains relative to their wild counterpart, the red junglefowl (G. g. gallus). Here, we tested for differences between junglefowl and chickens in the anatomy of the cerebellum, a brain region that is typically smaller in domesticates relative to wild populations. We quantified cerebellar anatomy of red junglefowl and white leghorn (WL) chickens with unbiased stereology. Relative to body and brain size, junglefowl have smaller cerebella than WL chickens and other chicken breeds. However, chickens and junglefowl do not have relatively smaller cerebella than other galliform species. WL chickens and junglefowl also differed in the proportional sizes of the granule cell and white matter layers within the cerebellum. Purkinje cell size did not differ between WL chickens and junglefowl, but WL chickens had more Purkinje cells. When compared with other galliform species, both WL chickens and junglefowl had fewer and smaller Purkinje cells relative to cerebellum size. Overall, these results suggest that the cerebellar anatomy of Gallus species differ from other galliforms and that the effects of domestication on the chicken brain differ from that of other domesticated species.
