cost-benefit approach.docx

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Department
Biomedical Engineering
Course Code
BMEN 515
Professor
William Huddleston

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Description
 cost-benefit approach: assumes an animal has only a limited amt of time and energy to devote to activities; [costs must not outweigh benefits]; ecologists can make predictions, design experiments, and make observations explaining why patterns evolve the way they do  benefits of behaviour are improvements in survival and reproductive success; 3 costs  energetic cost: difference btwn energy at rest and energy used to perform behaviour  risk cost: increased change of getting killed/injured when performing behaviour  opportunity cost: sum of benefits the animal forfeits by not performing other behaviours  Moore and Marler: male lizards with more testosterone spent more time patrolling territories, doing advertising displays, used 1/3 more energy than control males. They had less time to feed, got fewer insects, stored less energy, died at higher rate  some animals defend all-purpose territories that include all resources (tigers, songbirds)  food supplies cannot be defended if widely distributed or fluctuate a lot (ex oceans)  some animals defend territory used only for mating (male grouse congregate on display grounds, defending small area. Males often use so much energy that less tired males eventually evict them)  foraging theory: helps us understand survival (ultimate) value of feeding choices; benefits = nutritional value, and costs similar to those for territorial defense  more rapidly an animal captures food, more time+energy it will have for other things  characterize each type of available food item in 2 ways: time it takes animal to pursue, capture, and consume item; and by amt of energy an item contains  most valuable food type is one that yields most energy per unit of time expended o can determine rate at which an animal would obtain energy given foraging strategy o animal gains most energy by taking only most valuable type and ignoring all others; but as that type depletes, it adds less valuable types (ex fish would ignore small water fleas if there are large ones)  for bluegills, only energy content of water fleas mattered; some animals travel great distances for nutrients  some ingest food for other reasons. Frogs get poisons from eating ants that have evolved poisons as defense mechanisms b/c frogs are immune to poisons  spices in food preparation protects ppl from contaminated food; most commonly used spices inhibited growth of some food-borne bacteria; perhaps spices disguise taste/smell of spoiled food. But eating spoiled food could be dangerous, and natural selection is not likely to have favored ppl who ate rancid food, no matter how tasty  most animals associate with others for mating partners and/or for resources it controls  males initiate courtship, hardly reject receptive females, fight for females  females seldom fight and often reject males o b/c sperm are small and cheap to make, very large # of offspring, males can incre
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