Liver glycogen, glucose mobilization and freezing survival in chorus frogs, Pseudacris triseriata

We compared liver glycogen stores and glucose mobilization during freezing among winters in chorus frogs, Pseudacris triseriata, where populations varied in freezing survival. We also characterized tissue glycogen levels across the annual cycle. Frogs with low liver glycogen stores mobilized low amounts of glucose during freezing, and these were correlated with population variation in freezing survival. Moreover, liver glycogen stores were significantly and positively related to body mass. These data suggest that chorus frogs store liver glycogen in preparation for hibernation and that body size and glycogen stores must reach threshold levels for successful survival of freezing bouts during the winter.