Abstract
Chicken may have fascinated the ancient human not only because of their usefulness as potential food but also because of their colorful appearance and political landmark. At present there are many varieties that have been established through domestication and artificial breeding. Japanese ancients has domesticated and bred chickens for various purposes for a long time. For example, fighting cocks, Shamo, and long-crowing chickens, Naganakidori, are typical examples that must have been bred for the purposes of entertainment and appreciation, which are important parts of human culture. We intend to elucidate the evolutionary process of the Japanese domesticated chicken. To create novel varieties of ornamental chickens, intensive artificial selection was operated on ancestral Shamo populations, resulting in profoundly differentiated Japanese domesticated chickens. In this study, we seek to clarify the relationship between variations of Dopamine Receptor D4 and behavior of chickens. We also seek to analyze the evolutionary background to confirm Proline repeat numbers and we predicted the 3D structure of a chicken dopamine receptor in this research.