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Annexe III
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temperature-dependent sex determination species (Bull & Vogt, 1981; Mrosovsky & Pieau,
1991). During the TSP, fluctuations of temperature influence sex differentiation, so an
increase of the TSP may influence the sex of the embryo, irremediably determined only at the
end of the TSP (review in Pieau & Dorizzi, 2004). In this context, moisture conditions may
indirectly influence sex determination of the embryo. In our case, we could not detect a
possible effect of moisture substrate on sex partly because we performed our experiment at
constant incubation temperature. This points out the importance to use incubations conditions
that are ecologically relevant (i.e. fluctuating water potentials and temperatures) in laboratory
studies.
Hatchling and yearling mass
Most of studies have suggested that effects of incubation environment (temperature and
moisture) may influence the pattern of selective process of phenotypic traits affecting
individual fitness (Gutzke et al., 1983; Morris et al., 1983; Miller, Packard & Packard, 1987;
Finkler, 1999; Packard et al., 1999b; Angilletta et al., 2000). Hatchling mass was often
proposed as affecting a component of lifetime fitness in turtles, with larger hatchlings
supposed to have an advantage over smaller individuals (i.e. the “bigger is better hypothesis”;
(see Miller et al., 1987; Packard & Packard, 1988; see Janzen, 1994)). This hypothesis
considers hatchling mass as a good index of hatchlings quality: larger individuals may have a
better survival rate (Janzen, 1993; Janzen, Tucker & Paukstis, 2000; Kolbe & Janzen, 2002).
In our experiment, we detect a significant and positive correlation between hatchling mass
and the time spent by eggs on wet substrate during incubation (Figure 3.b). We also showed a
positive relation between initial egg mass and mass of hatchlings (Figure 3.a). Moreover,
moisture substrate influences the mass of hatchling turtles in interaction with the initial mass
of the eggs (Table 2.3). Finally, hatchling mass varied also significantly among clutches,
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