title: Evolution of a balanced sex ratio by frequency-dependent selection in a fish.
abstract: Balanced (1 to 1) sex ratios are thought to evolve by a process known as frequency- dependent selection of the minority sex. Five populations of a fish with genetically based variation in temperature-dependent sex determination were maintained for 5 to 6 years in artificial constant-temperature environments that initially caused the sex ratio to be highly skewed. Increases in the proportion of the minority sex occurred in subsequent generations until a balanced sex ratio was established, thus confirming a central premise underlying the theory of sex-ratio evolution.
authors.forename: D O
authors.initials: DO
authors.lastname: Conover
authors.forename: D A
authors.initials: DA
authors.lastname: Van Voorhees