Comparative Functional Morphology of Skulls among Japanese Breeds of Domestic Fowls

Abstract

The skull of six Japanese fowl breeds, namely, Chabo, Oh-Shamo, Onagadori, Shokoku, Tosajidori, and Totenko, were morphologically compared in this study. The morphological differences in the skull size and shape among the breeds were as follows. 1) Oh-Shamo possessed a wide bill, thick bill tip, small orbits and wide mandibular joint. The characteristics of the bill and mandible were interpreted as functional characteristics to endure the shock of pecking. We suggest that the small orbits and a wide frontal bone help in protection from pecking in games. 2) Chabo possessed a small skull. In terms of shape, this breed possessed relatively large orbits, a wide and high skull and a short bill. The wide and high skull and the short bill formed a circular-shaped face. We propose that these characteristics have led to its characterisation as ornament-type fowl. 3) Totenko, Shokoku, Onagadori and OhShamo possess a long mandible. The long mandible led to an increase in the volume of the oral cavity. The wide resonance space is responsible for the low-frequency voice. The low-frequency crowing of Totenko, Shokoku, OhShamo and Onagadori is a result of the enlarged resonance space created by the long mandible. The orbits of Totenko and Onagadori were larger than those of Shokoku and Oh-Shamo. We suggest that Shokoku possessed the small orbits as a fighting cock. Since Onagadori and Totenko had been bred as ornament-type fowl, they possessed larger orbits.

Morphological variation in brain through domestication of fowl

“…; Kudo et al. ) and ornaments (Tixier‐Boichard et al. ); however, much variation in brain shape can be explained by size.…”

“…The changing shapes determined in various avian species in our previous studies are consistent with those seen in various breeds of domestic fowl. Domestic fowl have been artificially selected for various purposes, thereby resulting in highly variable phenotypes, including feather or body color (Sunde, 1992;Castañeda et al 2005;Eriksson et al 2008;Sheppy, 2011), feather morphology (Bartels, 2003), skeletal morphology (Hayashi et al 1982;Endo et al 2012;Kudo et al 2016) and ornaments (Tixier-Boichard et al 2011); however, much variation in brain shape can be explained by size. Fig.…”

Whole-genome resequencing of Xishuangbanna fighting chicken to identify signatures of selection

“…CBFB ( core - binding factor subunit beta ) and GRHL3 ( grainyhead - like 3 ), which are critical for growth and development of the craniofacial skeleton [ 26 , 27 ]. These genes may explain why fighting chickens have a wider mandibular joint and frontal bone as compared to other breeds [ 28 ]. Many of the genes identified are related to limb development, i.e.…”