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Updated: Jul 12, 2026

Basic Methods for the Study of Reproductive Ecology of Fish in Aquaria
Published on: July 20, 2017
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.
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