Data from: Evolutionary stable sex ratios with non-facultative male-eggs first sex allocation in fig wasps

Sex allocation theory has long generated insights into the nature of
natural selection. Classical models have elucidated causal phenomena such
as local mate competition and inbreeding on the degree of female bias
exhibited by various invertebrates. Typically, these models assume mothers
facultatively adjust sex allocation using predictive cues of future
offspring mating conditions. Here we relax this assumption by developing a
sex allocation model for haplodiploid mothers experiencing local mate
competition that lay a fixed number of male eggs first. Female egg number
is determined by remaining oviposition sites or remaining eggs of the
mother, depending on which is exhausted first. Our model includes
parameters for variation in foundress number, patch size, fecundity and
offspring mortality that allow us to generate secondary sex ratio
predictions based on specific parameterizations for natural populations.
Simulations show that: 1) in line with classical models, factors that
increase sib-mating result in mothers laying relatively more female eggs;
2) high offspring mortality leads to relatively more males as
fertilization insurance; 3) unlike classical model predictions,
sub-optimal predictions, such as more males than females are possible. In
addition, our model provides the first quantitative predictions for the
expected number of males and females in a patch where typically only one
mother utilizes a given patch. We parameterized the model with data
obtained from seven species of southern African fig wasps to predict
expected means and variances for numbers of male and female offspring for
typical numbers of mothers utilizing a patch. These predictions were
compared to secondary sex ratio data from single foundress patches, the
most commonly encountered situation for these species. Our predictions
matched both the observed number and variance of male and female offspring
with a high degree of accuracy suggesting that facultative adjustment is
not required to produce evolutionary stable sex ratios.