Thursday, February 24, 2011

Blog #4

Describe the three types of selection: directional, stabilizing and disruptive and give an example of each in your own words

  • Directional Selection: Directional selection is selecting the individual with the most extreme variations in traits in a population. An example is choosing the fastest greyhound dog among a group of them. Then you pick the fastest one from their offspring. When you continue this, you end up with a really fast greyhound.
  • Stabilizing Selection: Stabilizing selection is selecting the individual with the common, average traits in a population. An example is a Siberian Husky. If a Siberian Husky had heavy muscles, it would sink in the snow but if it had lighter muscles, it wouldn't be able to pull the sled. So choosing a medium Siberian Husky would be able to move through the snow and pull the sled.
  • Disruptive Selection: Disruptive Selection is selecting the extreme traits in a population that would survive a sudden change in the environment. For example, when the Earth was hit by a meteor, there were large tidal waves,  increasing number of earthquakes, inadequate supply of food, and little oxygen. Larger animals would not have survived in this because they needed a lot of food and oxygen, but evidence shows that disruptive selection actually picked the traits that would help the animals in these conditions, thus making them survive.

No comments:

Post a Comment