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• Published: 10 July 2000

Brooks reports in the 6 July Nature that male guppies that are sexually more attractive are also evolutionarily less fit (Nature 2000, 406:67-70). This may reflect negative pleiotropic effects of genes for attractiveness, such as the energetic cost of creating large amounts of pigments. Alternatively, deleterious alleles may be hitching a ride in the region of the Y chromosome that has attractiveness genes such as those for color patterns. The increased attractiveness of the male fish ensure the chromosome's genetic survival, but suppression of recombination on the Y chromosome means that the deleterious alleles are not weeded out.