Abstract:
Where a maternal trait influences the fitness of sons or daughters, mothers would be expected to bias the
sex ratio towards the sex whose fitness they are more able to increment. In many polygynous species,
maternal characteristics affect the fitness of sons more than that of daughters, but, in meerkats, variance
in female reproductive success exceeds variance in male reproductive success and maternal rank affects
the success of daughters more than sons. Dominant females would therefore be expected to produce an
excess of daughters, a reversal of the hypothesis’ usual predictions. In a long-term data set, despite
a strong effect of maternal rank on daughters’ success, we found no indication that dominant females
produce female-biased litters. Offspring sex ratios did not deviate significantly from equality, and were
also unaffected by maternal mass, age or number of previous litters produced in the same season. We
suggest that potential advantages to both mother and offspring of producing and developing in mixed
litters may result in the adaptive maintenance of an equal offspring sex ratio.
