[ **up: [[Vertebrates]]** ] --- # Platyfish [[2025-0313. 'The WXY system in platyfish (Bull, 1983) is a three-sex pecking-order dominance system in which mating between the first and the third sex is not allowed.'|'For example, the WXY system in platyfish (Bull, 1983) is a three-sex pecking-order dominance system in which mating between the first and the third sex is not allowed.']][^1] [^1]: Yoh Iwasa and Akira Sasaki, ‘[[Iwasa & Sasaki. ‘Evolution of the number of sexes’, 1987.|Evolution of the number of sexes]]’, *Evolution* 41, Issue 1, 1 January 1987, p. 59.