Environmentally induced variation in body sire and condition in hatchling snapping turtles (Chelydra serpentina)

We performed an experiment at a field site in north-central Nebraska, U.S.A ., to assess the importance of the nest environment as a determinant of bod y size and condition in hatchling snapping turtles (Chelydra serpentina). T he contents of newly constructed nests were manipulated by reciprocal trans plant so that each of several nests received a complement of eggs from each of several females. The eggs were recovered from nests after weeks and all owed to complete incubation under standard conditions in the laboratory. Li ve mass, dry mass and water content of carcasses, and dry mass of unused yo lk varied significantly among hatchlings that incubated in different nests. This variation apparently resulted from variation in water exchange by egg s, because embryos in eggs that absorbed water during 8 weeks in the field consumed more of their yolk, grew to a larger size, and were better hydrate d at hatching than embryos in eggs that lost water to the nest environment. Phenotypic variation of the magnitude observed in this investigation may a ffect survival of hatchlings, and therefore needs to be considered explicit ly in theories for the evolution of life histories in these long-lived anim als.