The Trivers and Willard model (TWM) predicts that for sexually dimorphic polygynous mammals, mothers able to provide a high level of care should bias offspring sex ratio in favor of sons. Contradictory results of empirical studies, however, suggest that selective pressures for adaptive offspring...

For dimorphic species in which the variance in reproductive success of males is more pronounced than that of females, theories of adaptive variation in sex ratio predict that mothers should invest more heavily in sons than in daughters. By using harvest data from a forest-dwelling red deer...