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Annexe III
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ABSTRACT
Temperature and hydric conditions within the nest on development and survival of
embryos and phenotypes of hatchlings has been well documented in ectothermic sauropsids.
Most authors, however, have only considered constant hydric conditions within the nest, even
though developmental moisture in natural settings fluctuates considerably on a daily and
seasonal basis. A laboratory study was performed on 188 eggs from 26 clutches in the redeared
slider turtle (Trachemys scripta elegans) to determine the effect of hydric variance on
hatching success, incubation length and hatchling mass. We also tested the effect of hydric
condition on survival rate after one year. Eggs were incubated on substrates with 3 different
water potentials (i.e. dry, intermediate and wet) at constant temperature yielding both sexes
(i.e. 28.9 ± 0.1°C). Transfers between substrates were performed every 2 days to mimic
variations of hydric conditions. Hatching success was found to be independent from hydric
conditions but incubation length and hatchling mass were negatively related with time spent
on dry substrate, suggesting that hydric conditions may affect hatchling quality. However,
moisture substrate seems to have a very short-term effect on hatchling phenotype, while
sexual phenotype seems to have a great influence on mass and growth of hatchlings up to one
year.
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