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Free keywords:
mate choice; host-parasite co-evolution; MHC immuno genes;
ornament; odor
Abstract:
tFemale preference for secondary sexual male ornaments that are handicapping survival has been anevolutionary puzzle since Darwin. The Hamilton-Zuk hypothesis assumes that costly ornaments can beproduced only by those males that carry the genes for resistance against the current infectious disease.I review studies in fishes that indeed bright colors can only be displayed by males in good health andfemales prefer healthy males by choosing the brighter ones. On the other hand, female vertebrates fromfish to humans smell out partners that provide the complementary genes of the major histocompatibilitycomplex (MHC) to help them producing offspring with the optimal number of different MHC alleles. Insticklebacks females have a two-step choice. Using smell they approach a male that offers the optimallycomplementary number of MHC alleles. When they can see the male, they accept it only when it is brightand thus offers in its complementary set of alleles the specific MHC allele providing resistance againstthe current disease as revealed by the male’s sexual ornamentation.
