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Annexe III
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Change in egg mass – We used a mixed linear model with repeated measures using the SAS
Procedure MIXED, that included fixed and random factors. Time of weighing was the basis
for repeated measures. In a first model, independent fixed effects included time at the
measure, the incubation period (1,2 or 3) as a qualitative factor, the substrate moisture at the
time of the current measure (Wet, Intermediate or Dry), the moisture substrate encountered by
the egg five days before the current measure (denoted as “memory effect”) and the offspring
sex (male “M” or female “F”). Initial egg mass was added as continuous individual covariable,
as well as all three-way interactions. Clutch identity and all two-way interactions
with clutch were defined as random effects. In a second model, we replaced the factors
representing the period of incubation and the substrate moisture with three qualitative factors
describing successive substrate moisture encountered by eggs for each period of incubation.
Because we performed multiple comparison tests for the data set, we readjust the p-value of
the significance level alpha in your statistical test by the Bonferroni method.
Incubation length – We used a generalized mixed model, which included fixed and random
effects and a gamma distribution with a log-link function as the error distribution. Clutch
identity and the two-way interactions were defined as a random factor and initial egg mass,
sexual phenotype of embryos, hydric conditions during incubation and all two-way
interactions were defined as fixed factors. Hydric conditions was represented by two
quantitative measures of times elapsed on wet and dry substrate during the course of
incubation.
Hatchling and yearling mass – We used mixed linear models. Clutch identity and its
interactions were defined as random factors. Initial egg mass, offspring sex, the duration of
incubation and the two-way interactions were defined as fixed factors, in addition to the times
elapsed on wet and dry substrates.
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