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 equal temperament are closer to Pythagorean tuning than that of 55. Thus Mercator's comma and the Holdrian comma are two distinct but related intervals. The name "Arabian comma" may be inaccurate; the comma has been employed mainly in Turkish music theory by Kemal Ilerici, and by the Turkish composer Erol Sayan. The name of this comma is "Holder koması" in Turkish. For instance, the makam "rast" (similar to the Western major scale) may be considered in terms of Holdrian commas: while in contrast, the makam "nihavend" (similar to the Western minor scale): has medium seconds between d–e, e–f, g–a, a–b,