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
Comma are three or more items listed. The word "comma" comes from the Greek (), which originally meant a cut-off piece; specifically, in grammar, a short clause. A comma-shaped mark is used as a diacritic in several writing systems, and is considered distinct from the cedilla. The rough and smooth breathings () appear above the letter in Ancient Greek, and the comma diacritic appears below the letter in Latvian, Romanian, and Livonian. The basic comma is defined in Unicode as , and many variants by typography or language are also defined. Some languages use a completely different sort of character for