Abstract:
Female hymenoptera are renowned for their ability to adjust offspring sex ratio to local mate competition. When two females
share a patch, they frequently produce clutches that differ in size, the female with the larger clutch optimally producing a more
female-biased sex ratio and vice versa. Females can base their sex allocation on their own clutch size only (“self-knowledge”) or
on both females’ clutch sizes (“complete knowledge”). Few studies have genotyped offspring so that each mother’s contribution
can be considered separately while none has found that both sources of information are used simultaneously. We genotyped
2489 wasps from 28 figs and assigned their maternity to one of the two foundress females. We argue that likelihood is a very
convenient method to compare alternative models, while fitness calculations help to appreciate the cost ofmaladaptation.We find
that the pollinating fig wasp Platyscapa awekei simultaneously uses its own as well as the other females clutch size in allocating
sex. Indeed, the complete knowledge model explains the data 36 times better than the self-knowledge model. However, large
clutches contained fewer males than the optimal predictions leading to a median selection coefficient of 0.01.
