POOPATANAPONG, AMY*; SCHWABL, HUBERT: Male badge size and maternal yolk steroids in House Sparrows.

The good-genes hypothesis of female mate choice and sexual selection predicts that offspring fathered by preferred males will have increased fitness resulting from inherited superior male genes. However recent studies showed that females deposit more yolk androgen into their eggs when mated to more attractive males than when mated to less attractive males (Gil et al. 1999). Therefore mothers may be modifying their offspring’s fitness in response to mate quality through differential investment of non-genetic resources, namely through maternal yolk androgens. We tested in house sparrows if females deposit more androgens into their egg when mated to males with large throat badges, a trait assumed to be preferred by females. Both wild and aviary kept females did not deposit more yolk androgen for mates with larger badges. Nor did they vary their egg mass or clutch size in relation to badge size. However, yolk androgen concentrations changed seasonally, with eggs laid late in the season having higher yolk androgen concentrations than eggs laid early. These results do not support the hypothesis that females vary androgen allocation to eggs in response to perceived male quality. Further studies are required to identify the variables and conditions that influence differential yolk androgen allocation.