Positive genetic correlation between female preference and preferred male ornament in sticklebacks

Abstract

A NUMBER of population genetics models predict the evolution of male sexual ornaments through female choice1, but their genetic assumptions and predictions have hardly been investigated2,3. A key feature of these models is a positive genetic correlation between male ornaments and female preference for them4. Here I test this prediction at the within-population level with three-spined sticklebacks, Gasterosteus aculeatus, which show conspicuous sexual dichromatisnr. Intense red males are preferred in various situations6–10, but there is great intrapopulational variation in redness both among wild-caught6,10 and among laboratory-bred males11, which is partly environmental6 and may be partly genetic12,13. Also, females show considerable intrapopulational variation in their preference for redder males6,8,9, which is partly environmental8,9. Wild-caught, intense red males and dull males were crossed with a number of females from the same population in a full-sib/half-sib breeding design. Daughters were tested for their preference for more intensely red males, and the sons' coloration was quantified. Both traits showed genetic variation. Also the redness of the sons correlated with the preference for red of their sisters, thus the two traits show positive genetic correlation.