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 splice as "furthermore", "however", or "moreover") to separate two independent clauses instead of using a coordinating conjunction. Comma splices are also occasionally used in fiction, poetry, and other forms of literature to convey a particular mood or informal style. Some authors use commas to separate short clauses only. The comma splice is more commonly found in works from the 18th and 19th century, when written prose mimicked speech more closely. Fowler's Modern English Usage describes the use of the comma splice by the authors Elizabeth Jolley and Iris Murdoch: Journalist Oliver Kamm writes of novelist Jane Austen's use of the comma