Offspring emergence and starvation tolerance
During the 50-day pupal observation period, 96% of 355 pupae from the
control, 93% of 187 pupae from the mating delay, and 91% of 232 pupae
from the nutritional stress group emerged successfully. All emerged
offspring subjected to starvation were dead by 15 days post emergence.
Although the wet weight of pupae was similar between females and males
(Fig. 4a), across all three treatments there was strong evidence that
female offspring survived on average longer than males, but not by more
than a day (Tables S6 19 – 21), with ω ≤ 0.01 for models not
including sex (Tables S6 16 - 18, Fig. 4b).
There was strong evidence for an additional effect of maternal age on
offspring starvation tolerance, in addition to offspring wet weight, for
the nutritional stress treatment (models without age ω = 0.000).
Offspring from young mothers in the nutritional stress treatment were
particularly vulnerable to starvation (Fig. 4b), with evidence for a
cubic effect of maternal age in this treatment (cubic effect including
random intercept ω = 0.705). While there was also evidence for
maternal age effects on offspring starvation tolerance in the other two
treatments, there was not sufficient information in the data to quantify
the relationship between maternal age and offspring starvation tolerance
for the control or mating delay treatments (lowest AIC model: control –
quadratic effect and no random effects ω = 0.298; mating delay –
quadratic effect with no random effects ω = 0.212) (Tables S6
16-17).
For the mating delay treatment, singular fits were obtained for models
assuming a quadratic or cubic effect of mother age and including a
random intercept and slope, therefore there was not sufficient data to
assess for this treatment whether differences among individual mothers
carried through to emerged offspring starvation tolerance. There was
also insufficient information in the data to provide evidence for
among-mother variation in the control treatment, with the difference in
AIC weights between models with and without random effects
<0.15 (Tables S6 16 - 18). However, there was evidence for an
effect of individual mother on starvation tolerance in the nutritional
stress treatment (all models without random effects ω ≤ 0.04)
(Tables S6 16 - 18), but not for variation among individual mothers in
the effect of maternal age on offspring starvation tolerance (ω ≤0.005).
The results of the above analyses for the probability of abortion,
offspring wet weight and offspring starvation tolerance were unaffected
by removing from the analysis mothers in the nutritional stress
treatment that had died before the end of the experiment. The analyses
can be found in S10 File and compared with results in S6 File.