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
T-comma the correct keyboard (ro comma) since at least 2005, selecting this keyboard from the user interface (e.g. GNOME Keyboard Properties) has only recently been made possible. T-comma T-comma (majuscule: Ț, minuscule: ț) is a letter which is part of the Romanian alphabet, used to represent the Romanian language sound , the voiceless alveolar affricate (like "ts" in "bolts"). It is written as the letter T with a small comma below and it has both the lower-case (U+021B) and the upper-case variants (U+021A). The letter was proposed in the "Buda Lexicon", a book published in 1825, which included two texts by