Figure 1.8: The zebrafish, a model genetic organism, has been instrumental in helping to identify genes encoding pigmentation differences among humans. (a) Human ethnic groups differ in degree of skin pigmentation. (b) The zebrafish golden mutation is caused by a gene that controls the amount of melanin pigment in melanosomes.
[Part a: PhotoDisc/Getty Images. Part b: Keith Cheng/Jake Gittlen, Cancer Research Foundation, Pennsylvania State College of Medicine.]