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Annexe III
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suggesting a genetic and heritable component that permit natural selection to act on this
phenotypic trait (Stearns, 1992). So, our results support a potential influence of hydric
conditions within the nest on quality (i.e. mass) of hatchlings that may affect individual
fitness.
However, we also found that significant effects of moisture substrate on juvenile mass
disappeared approximately after one year of life (Table 2.4). Thus, hypothesis that larger mass
at hatching would confer faster growth on hatchlings, regardless of the source of differences
in mass at hatching was refuted (Brooks et al., 1991). We didn’t either detect an effect of
initial egg mass or clutch on yearling mass (Table 2.4). On the other hand, we detected a high
and significant effect of offspring sex, with females heavier than males (Figure 4). Hydric
conditions within the nest may thus have only short-term effects and may influence juvenile
quality only in the early stage of life.
CONCLUSION
Mortality of embryos in Trachemys scripta elegans, a turtle with flexible-shelled eggs, was
not affected by the range and change of moisture levels used in our experiment. However, we
performed this experiment under constant incubation temperature, while temperature and
moisture probably exert a combined effect on eggs and embryos. Other studies confounding
effects of temperature and water potential. Finally, few authors investigated the range of
substrate moisture in association with nest temperature that might influence eggs and resultant
hatchlings, as well as fluctuating water potentials (Gutzke et al., 1986; Tucker et al., 1997;
Tucker et al., 1998; Ji et al., 1999; Hewavisenthi et al., 2001; Tucker, Paukstis & Janzen,
2001).
As expected, incubation length and hatchling mass were negatively related with time on dry
substrate, thus hydric conditions may affect hatchling quality. However, moisture substrate
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