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
Holdrian comma and b–c', a medium second being somewhere in between 8 and 9 commas. Holdrian comma In music theory and musical tuning the Holdrian comma, also called Holder's comma, and sometimes the Arabian comma, is a small musical interval of approximately 22.6415 cents, equal to one step of 53 equal temperament, or formula_1 (). The name comma is misleading, since this interval is an irrational number and does not describe the compromise between intervals of any tuning system; it assumes this name because it is an approximation of the syntonic comma (21.51 cents)(), which was widely used as a measurement of