FOOD DEPRIVATION, DOMINANCE RANK, AND PARENTAL INVESTMENT IN HOUSE MICE

Abstract

The Trivers and Willard (1973) theory postulates that female polygynous mammals in good condition should maximize their fitness by investing more in male offspring then in female offspring, while females in poor condition should invest more in female offspring than in male offspring. CF1 mice were used to test this hypothesis. A control group, a premating group (deprived of food every other day one week prior to mating), and a gestation group (deprived of food every third day during gestation) were tested and compared. Both the premating and gestation groups had a higher proportion of female pups than the control group. The premating group had higher fertility than the control or gestation groups. High infant mortality caused the proportions of female pups of the premating group to be closer to the control proportion after the third day. The sons of control, premating, and gestation groups had similar birth weights. However, at adulthood the control males outweighed the premating and gestation males. When dominance ranks were tested among control sons and premating and gestation sons of similar weights, the premating and gestation sons tended to be dominant. When dominance ranks were tested between higher weighing control males and lower weighing premating males, the higher weighing control males were dominant in all cases. Analysis reveals secondary sex ratio results as predicted by the Trivers and Willard (1973) theory as well as some differences in dominance ranks of the male pups which may reflect differences among strains.