Sexual selection for a handicap: A critical analysis of Zahavi's model
Abstract
In Zahavi's model, females with a preference for conspicuous males, or for males with some other kind of handicap to survival, gain an advantage because their offspring have an increased fitness as a result of the more intense selection of the handicapped males. To gain such an advantage, however, extremely intense selection would have to act on the handicapped males and almost equally intense selection on the others. In realistic cases, the intensities of selection required by Zahavi's model cannot be achieved. Two premises implied by the model are false. The first is the assumption that selection continues to produce an advantage for the females with the preference. Selection cannot continue to do this, however: the fitness of the handicapped males cannot increase indefinitely, and any initial advantage that might be produced by extremely intense selection must soon be lost and turn to disadvantage. In the second premise, selection is assumed to favour the same combination of characters in both handicapped and non-handicapped males. This is also false: disruptive selection would favour different combinations of characters in these individuals; the combination of characters favourable to handicapped individuals would be unfavourable when passed on to non-handicapped offspring thus eliminating any advantage that the females with the preference might gain. The premises and logic of Zahavi's model are therefore false.
- Publication:
-
Journal of Theoretical Biology
- Pub Date:
- 1976
- DOI:
- 10.1016/0022-5193(76)90006-0
- Bibcode:
- 1976JThBi..57..345D