POSITIVE GENETIC CORRELATION BETWEEN FEMALE PREFERENCE AND PREFERRED MALE ORNAMENT IN STICKLEBACKS

A NUMBER of population genetics models predict the evolution of male s exual ornaments through female choice1, but their genetic assumptions and predictions have hardly been investigated2,3. A key feature of the se models is a positive genetic correlation between male ornaments and female preference for them4. Here I test this prediction at the withi n-population level with three-spined stickle-backs, Gasterosteus acule atus, which show conspicuous sexual dichromatism5. Intense red males a re preferred in various situations6-10, but there is great intrapopula tional variation in redness both among wild-caught6,10 and among labor atory-bred males11, which is partly environmental6 and may be partly g enetic12,13. Also, females show considerable intrapopulational variati on in their preference for redder males6,8,9, which is partly environm ental8,9. Wild-caught, intense red males and dull males were crossed w ith a number of females from the same population in a full-sib/half-si b breeding design. Daughters were tested for their preference for more intensely red males, and the sons' coloration was quantified. Both tr aits showed genetic variation. Also the redness of the sons correlated with the preference for red of their sisters, thus the two traits sho w positive genetic correlation.