Litter sex ratios in the golden hamster vary with time of mating and litter size and are not binomially distributed.

摘要: Pregnancy rates, litter sizes, and sex ratios vary strongly with the time in estrous cycle at which female golden hamsters (Mesocricetus auratus) are mated. Early matings tend to produce relatively high pregnancy large litters, female-biased ratios, while late low small male-biased ratios. Time of mating size therefore correlated, but each appears have an independent effect on ratio: ratio positively holding constant, negatively constant. At greater than two, variance is less binomial expected hypotheses sampling a constant probability producing male. The main features distribution can be generated from causal model different probabilities male apply “early” “late” conceptions within litter. relationship between mean potentially consistent several models for evolution adaptive sex-ratio variation.