BIOL 1070 Lecture Notes - Lecture 22: Ground Squirrel, Metabolic Water, Blubber

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pucemole727

30 Mar 2016

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Coninue to explore some of the strategies used by endotherms to survive the cold. Consider some factors that are relevant to predicions about the survival of polar bears under climate change. Examine some key diferences between related species of bears. Answers: bears are not true hibernators, but they do reduce their breathing rate, metabolic rate and temperature during denning in the winter. Compared to true hibernators such as ground squirrels, a bear"s metabolic rate is signiicantly less depressed and body temperature reduced only a litle. Bears do not have to coninually wake up, and can go more than 100 days without eaing, drinking or passing waste. Female bears den and stay awake when they are nursing cubs The reason why the ground squirrel has to have spikes in temperature that brings it out of hibernaion is though to be a reboot of the immune system. Deep hibernaion is not accessible for animals with a large body mass.

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Please help answer both parts of the question with full detail.Will give good rating.

a) Contrary to what we may have grown up learning, only smallanimals hibernate (not completely trueâ¦black bears are now believedto hibernate, however itâs a different mechanism than smallanimals-more on this later in the semester). Hibernation occurswhen an animal lowers its metabolic rate below itâsBMR.

Lets explore this relationship between hibernation and bodysize, by considering stored energy and the rate of energymetabolism (utilization). Here, you will calculate whetherhibernation is necessary by comparing a 1200 pound polar bear and a1.5 pound grey squirrel (like those living here in Columbus). Wecan compare how long each could survive during a winter fast ifthey used only body fat as their energy source, and do nothibernate (which requires a drop in metabolism below the BMR). Theweight-specific Basal metabolic rate (BMR) of mammals is 4.46M^-0.30 when expressed in units ofmLO₂consumed per gram of body tissue perhour and (importantly) weight is calculated ingrams. For this simple estimate, you may use BMR, but keepin mind that small animals have a larger increase in metabolismwith temperature than large animals. Calculate how long each animalcould survive on stored fat equal to 20% of its total body weight(this is a fairly reasonable fat amount found in both squirrels andbears in nature). Make sure you keep all units very clear duringthis calculation, there are many steps.

Potentially useful information:

The value of energy content of fat is 9.3 kCal per gram of fatand 2.0 L of O₂ are consumed per gram of fatmetabolized. There are 5280 feet in a mile, and 1.0 foot = 0.3048meters. One calorie = 4.184 joules. One pound (lb) = 454 grams andone ounce is 28.375 grams.

b) Given your results, what do you think might be the potentialsolutions for a) squirrels and b) polar bears for surviving throughthe winter (keeping in mind that food is scarce so they canât juststay awake and look for food!) This should only be a FEWsentences!

pinkzebra569

BIOL 1070 Lecture Notes - Lecture 22: Ground Squirrel, Metabolic Water, Blubber

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