The difference between black and yellow color in Labrador retrievers stems, for instance, from a single base change that inactivates a signal receptor in the pigment cells of yellow dogs.

• 比方说，拉布拉多犬的黑、黄毛色差异，是来自单一碱基改变，造成黄色拉不拉多犬的色素细胞讯号受体不活化。