PACKARD, G.C.*; PACKARD, M.J.: Environmentally Induced Variation in Size and Condition of Hatchling Painted Turtles

We manipulated the contents of newly constructed nests of painted turtles (Chrysemys picta) so that each of three nests received two eggs from each of the same five females. The manipulation was replicated on three successive days, thereby yielding a sample of nine nests and 15 clutches. The eggs then were allowed to incubate in the field for 54-56 days before they were brought into the laboratory to complete incubation at an optimal temperature and water potential. Both clutch and nest contributed significantly to variation in size and condition of hatchlings. Embryos in eggs that absorbed water from the nest environment mobilized more of the lipid and protein from their yolk and grew larger before hatching than did embryos in eggs that lost water to the surroundings. The relatively large hatchlings contained more storage lipid than did smaller animals, but the lipid reserve scaled with body size. Our findings point to an important role for water in modulating the metabolism and growth of embryonic turtles developing under natural conditions in the field. Supported by NSF (IBN-9612562).