Introductory Biology

36.1 Evolution of Behavior (Part 2)

Learning: the development of behaviors by experience. Learning can change the expression of innate behavior and the expression of behavior that are not innate. One kind of learning is habituation = animals learn to ignore a frequent, harmless stimulus.
  • Example: Most birds stay away from gardens with scarecrows at first. But if the position of the scarecrow does not change, the birds will ignore it and  not be afraid to go into the garden.
1.) Classical conditioningan animal comes to associate an unrelated response with a stimulus, it begins with an instinct and associates something else with it (more complex type of learning). It was first described by Ivan Pavlov while working with dogs. Meat powder (a stimulus) produces unconditioned response of salivation in dogs. Next, he presented the meat powder with a ringing bell (an unrelated/conditioned stimulus) and the dog eventually responded to the ringing bell, learning that the bell is associated with meat powder. The dog became conditioned to associate the ringing of the bell with a reward (meat powder).
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2) Trial-and-Error/ Operant conditioning: pairing two things that are not genetic and animals learn that performing a certain action will result in a reward or punishment. It was first described by B.F. Skinner who experimented with rats, placing them in a “Skinner box”.  The rats explored the box and would accidentally press a lever once in a while, and food would appear. After a couple of times the lever was pressed, the rat will learn that the it can obtain food by pressing the lever. The trial-and-error learning is very important to most vertebrates and it influences many behaviors essential to survival (like looking for food).
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3) Reasoning: the ability to analyze a problem & think of a possible solution. It involves using past experiences to develop an understanding of how to solve a problem. Animals that show reasoning ability are: primates & possibly dolphins, parrots, and octopuses. Example: a chimpanzee was placed in a room with boxes and a banana hung high overhead. Even though it has never been in this situation before, the chimpanzee stacked the boxes and was able to reach the banana = a behavior that requires reasoning. Also, Japanese snow monkeys learned to float grains on the water to separate the grain from sand.
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Many behaviors have both genetic and learned aspects. Imprinting: learning that can only occur during a specific period early in life, and cannot be changed once it occurs. Konrad Lorenz described imprinting in geese when he raised a group of newly hatched geese by hand. Example: young geese and ducks that have no innate recognition of their mother are genetically programmed to follow the first moving object they see during the short period after they hatch. Once the young birds imprint on an object, they prefer to follow it as they would their mother, even if it was a toy wagon box, or balloon.  The ability to imprint is genetic, but the process of imprinting is learned. So, learning determines the final shape of a genetically based behavior.
Insight learning: a type of learning that uses reasons to solve a problem. Crows learn very quickly. The ability to learn gives animals a huge advantage. Some examples are:  chimpanzees learning that if they poke sticks into trees, they can get termites, birds learning where to get food, and animals avoiding danger. Foraging; Bluegill sunfish examples: The type of food they eat depends on the density of the prey. High density of prey (lots of variety) they select prey to maximize its energy intake. Medium density of prey; preferably eats the larger one over the smaller ones. Low density of prey; not too picky. Hyenas hunt in a pack because they cannot be successful alone. Ducks are more successful when they form a circle when hunting fish. Molts: a bird molts when it sheds feathers. Animals often migrate long distances. Pigeons migrate together in a group for safety from a predator (hawk). Animals aggressively fight each other for a specific territory, access to mates, or resources. 
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One thought on “36.1 Evolution of Behavior (Part 2)

  1. Yurika,

    Great job with your entry for 36.1 (part 2!) on the evolution of behavior. You’ve covered all the ideas thoroughly. I’ll miss reading your blogs!!!

    Mr. F.

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