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Annexe III
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INTRODUCTION
In oviparous sauropsids, hatching success and hatchling phenotype depend greatly upon the
environmental conditions, especially when females lays eggs in a subterranean nest cavity and
abandon them, such as turtles and most crocodilians and squamate species do (Gutzke &
Packard, 1987; Brooks et al., 1991; Shine & Harlow, 1997). In the absence of parental care,
embryos and hatchlings are strongly affected by the physical conditions of the nest and
particularly by the temperature and moisture within the nest (Ewert, 1985).
Incubation thermal environment strongly influences embryonic growth rate (Pieau & Dorizzi,
1981; Webb et al., 1987; Deeming & Ferguson, 1989; Georges et al., 2005), incubation length
(Yntema, 1978), survival of embryos (Brooks et al., 1991) and even sex phenotype in species
with temperature-dependent sex determination (Bull, 1980; Janzen & Paukstis, 1991; Ewert,
Jackson & Nelson, 1994). Variations in nest temperature also influence neonate morphology
(Congdon, Fischer & Gatten, 1995; Brana & Ji, 2000; Ji & Du, 2001), physiology (Angilletta,
Winters & Dunham, 2000; Demuth, 2001; Vanhooydonck et al., 2001; Blumberg, Lewis &
Sokoloff, 2002; Lee et al., 2003), behavior (Shine et al., 1997; Burger, 1998; Nebeker &
Bury, 2000) and survival (Brooks et al., 1991; Pepin, 1991) in diverse species. Despite the
large amount of studies on the influence of temperature, this latter effect was often analyzed
regardless of substrate moisture effects (Willingham, 2005). However, in natural nests,
substrate moisture fluctuates greatly during the incubation period, in association with the
pattern of atmospheric temperatures and precipitations (Packard et al., 1985; Bodie, Smith &
Burke, 1996). These variations of water potential are particularly important for species that
bury shallow nests as aquatic turtles, where eggs may encounter several drought and flooding
events during incubation period (Moll & Legler, 1971; Plummer, 1976; Janzen, 1994; Kam,
1994).
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