Swallowtail butterfly tiger swallowtail), Y-linkage determines whether the females are either wild-type (yellow and black) or melanic (dark melanin replaces the yellow background). This genetic difference stems from the fact that melanism is controlled by a single gene, which controls the level of dopamine in the organism. The enzyme BAS, which assists dopamine in producing the yellow pigmentation, normally found on the wings' background, is suppressed. Without the pigmentation, the butterfly appears mostly black (the melanic form) and is a Batesian mimic of "Battus philenor", the pipevine swallowtail. There are also "Papilio glaucus" that are not wholly black; several possess an intermediate
Swallowtail shiner Swallowtail shiner The swallowtail shiner ("Notropis procne") is a North American species of freshwater fish in the Cyprinidae family. It has a slender and long body of about 40–55 mm. The shiner has a pale yellow back with a blue stripe on its silver side. It also has a silvery white belly. Its fins are yellowish and it has a dorsal fin originating above the back half of the pelvic fin base and a tail fin with a black spot at its base. Its snout is either slightly pointed or slightly rounded. The swallowtail shiner lives in warm creeks and