Presentation on theme: "Copy Right Bear Trust International 2011 For Education Use Only Two Adaptive Strategies Bears Have Evolved."— Presentation transcript:
Copy Right Bear Trust International 2011 For Education Use Only Two Adaptive Strategies Bears Have Evolved
Adaptive Strategies: Hibernation
Torpor Hibernation Short-term hibernation ? X Heart rate Metabolic rate Body temperature Breathing rate
Hibernation Heart rate Metabolic rate Body temperature Breathing rate Heart rate Breathing rate Metabolic rate
Hibernation Heart rate Metabolic rate Body temperature Breathing rate A LOT !A LITTLE Only about 10 degrees F Body temperature Heart rate Breathing rate Metabolic rate
Must wake up every week For hours Bears don’t do this Raise body temp Eat stored food Pass waste Go back to deep sleep Can go for 100 days without eating, drinking or passing waste
Enter dormancy fast Hard to awaken Enter dormancy slowly Easy to awaken
Torpor Hibernation Short-term hibernation ?
Winter Lethargy Winter Sleep Denning Period
It is a Period of Amazing Physiology! Can go for months without drinking, eating, urinating, defecating, or exercising Fat Tissues Water Calories Muscle and Organ Tissues Protein
We can learn a lot from bears Bears do not get dehydrated Implications for people with chronic kidney failure It is a Period of Amazing Physiology!
Denning bears have very high cholesterol levels Dissolves cholesterol gall stones, eliminating need for surgery It is a Period of Amazing Physiology! Bile juice Do not develop cholesterol gall stones Humans We can learn a lot from bears
Bears: no muscle or bone atrophy Space travel It is a Period of Amazing Physiology! We can learn a lot from bears
Do all bear species use this adaptive strategy?
Asiatic Black Bear ? Yes Denning period is similar to that of American Black Bear Enter den Nov-Dec Pregnant females give birth around Jan Emerge from den between March-April Southern Asia, Northeast China, Japan and Far Eastern Russia
Polar Bear ? Only pregnant females enter a den, give birth Nov/Dec, and emerge when cubs can trek state of “walking hibernation ” Do not overwinter in dens like brown bears and black bears Most remain active year-round Have ability to reduce their metabolic rate when food is scarce polar bears come ashore after ice melts in Hudson Bay each summer maintain normal body temps reduce metabolic rate recycle proteins
Spectacled Bear Giant Panda Bear Sun Bear Sloth Bear These bears appear to remain active year-round Although……… pregnant females build birthing dens or nests Live in areas where food sources are available year-round
Adaptive Strategy: ? Reproduction
Delayed Implantation ….fertilized egg divides a few times… …development STOPS! …several weeks before female enters maternity den… ….fertilized egg attaches to uterine wall…. ….cubs! If not, then embryo is reabsorbed back into female’s body Why is this reproductive strategy advantageous? Adaptive Strategy:Reproduction Female bear mates… …fertilized egg floats free in the uterus for several months … ….continues for about 8 weeks… ….development RESTARTS