Environmentally induced variation in size, energy reserves and hydration of hatchling Painted Turtles, Chrysemys picta

1. The contents of newly constructed nests of Painted Turtles, Chrysemys pi cta (Schneider 1783), were manipulated by reciprocal transplant so that eac h of several nests received a complement of eggs from each of several femal es. The eggs were recovered from nests after 8 weeks and allowed to complet e their incubation under standard conditions in the laboratory. The design of the experiment enabled us to distinguish between environmental and mater nal effects on attributes of hatchlings. 2. Several measures of body size and energy reserve varied among turtles ha tching from eggs that incubated in different nests, and certain of these me asures varied also among turtles hatching from eggs that incubated in diffe rent layers within nests. The effects of nest and layer were substantial. F or example, fat-free carcasses of hatchlings from one nest weighed 17% more than those of neonates from a second nest, but fat-free yolks from the for mer weighed only 53% as much as yolks from the latter. 3. Stepwise linear regression indicated that the size of hatchlings and the hydration and fat content of their carcasses were positively correlated wi th the net change in mass of eggs (which is an index to net water-exchange) while they incubated in the field. In contrast, both the fat and fat-free components of unused yolk were negatively correlated with change in mass of eggs. Although the statistical procedure is only correlative, the findings accord well with results of laboratory studies documenting a relationship between uptake of water by eggs, metabolism and growth by embryos, and size and condition of hatchlings. 4. Variation among hatchlings representative of different nests accounted f or 24% of the statistical variance in mass of dry, fat-free carcasses; 29% of the variance in mass of dry, fat-free yolks; 19% of the variance in mass of storage fat in yolks; and 11% of the variance in mass of storage fat in carcasses. Additional variation was detected between the upper and lower l ayers of nests. Such environmentally induced variation probably affects sur vival of neonatal animals in the field.