The Florant lab studies the ecological physiology of hibernators, specifically the yellow bellied marmot (Marmota flaviventris) and the golden mantled ground squirrel (Spermophilus lateralis).

   These animals have a cycle of obesity and anorexia that repeats yearly–in summer and early autumn, they become hyperphagic and hugely obese, nearly doubling their body mass in fat! In mid autumn the hibernator completely ceases food intake and enters multi-day torpor bouts that last throughout the hibernation season from October to April.  These multi-day torpor bouts are broken up by periodic arousals to euthermia, but the hibernator is basically at low tissue temperature (around 5 degrees C) without eating for seven months at a time.  During these torpor bouts, all body processes slow (breathing drops to 3-4 breaths per minute, heart beats 1-2 times per minute), and brain synapses seperate, leaving the animal effectively brain-dead throughout the course of the torpor bout.  In April, the hibernator emerges from hibernation and resumes normal euthermic functions.  Our lab examines the physiological and ecological processes associated with this amazing adaptation, including:

How do these animals become obese without the pathologies usually associated with obesity (heart disease, diabetes, atherosclerosis, etc.)?

What are the cues (hormonal, neurological, etc.) that cause an animal to completely shut off food intake and resume it again several months later?

How do these animals decrease heart rate and breathing to nearly zero with no adverse effects (ischema, reperfusion, etc)?

What are the effects of global climate change on hibernators? Animals can only store a certain amount of fat on their bodies–those that hibernate at higher ambient temperatures don’t recieve the same energy savings as those that can hibernate at 5 degrees. Even a few degrees change in ambient temperature can make a big difference.

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