9612562 Packard This is a proposal to investigate the adaptive strategies for overwintering by hatchlings of five species of turtles inhabiting shallow lakes and marshes in the central and northern Plains. Hatchlings of two species (snapping turtle, Blanding's turtle) emerge from their subterranean nests in late summer, and then move overland to lakes or ponds where they establish residence and spend the winter. Hatchlings of two other species (ornate box turtle, yellow-bellied mud turtle) dig down through the bottom of their nests and spend their first winter of life deep in the soil. And hatchlings of the fifth species (painted turtle) remain inside their shallow, subterranean nests throughout the winter, and do not emerge from their nests until the soil thaws the following spring. Why do three different adaptive strategies for overwintering exist in the assemblage of turtles when neonates of all the species presumably would benefit from being able to remain for the entire winter inside their nest cavity? Research that will be performed over a period of 3 years will examine the roles of morphology, physiology, and behavior in enabling neonatal turtles to survive their first winter of life. Special attention will be given the integument, because the skin seems to be a barrier to the penetration of ice from frozen soil into body compartments of neonatal painted turtles but not to the penetration of ice into body compartments of neonates of the other species. Accordingly, hatchling painted turtles apparently survive over winter by exploiting a capacity for supercooling and remaining continuously unfrozen. Hatchlings of the other species, however, cannot exploit supercooling because their integuments seem not to resist the penetration of ice into body fluids from the environment. The absence of such a cutaneous barrier has caused hatchlings of other species to tap behavioral means for avoiding situations that could result in inoculation, freezing, and death. Thus, the common thre at of cold may have resulted in the evolution of three different adaptive strategies for overwintering by hatchlings in the same assemblage of turtles. The research there fore will elucidate the principle that evolution commonly produces multiple answers to the same general problem. ***
