EV: Natural Selection Lesson
You're a Natural!
So What is Evolution?
It means that a species or a population (not an individual) will change over time as traits are passed on from generation to generation.
Two Parts to the Theory of Evolution (proposed by Charles Darwin)
- Living things here today are descended from common ancestry.
- Natural selection is a process that occurs when living things with favorable (inherited) characteristics survive to reproduce, thereby passing on those beneficial characteristics.
What Darwin Said
Charles Darwin (1809-1882), developed the basis for the Theory of Evolution after traveling around the world on the H.M.S. Beagle.
Click through the notes below to learn more about Darwin and how this trip influenced his ideas about evolution.
Survival of the Fittest
Types of Natural Selection
Stabilizing Selection |
Directional Selection |
Disruptive Selection |
---|---|---|
Favors the intermediate phenotypes. Predators cannot catch the medium-sized lizards (they are the fastest), you would see fewer small and large lizards over time. |
Favors one extreme or the other. Giraffes with longer necks get more nutrients from higher vegetation. That trait increases in the population over time. |
Favors extreme phenotypes. For the shells, predators could see the pink shell but not the other two (they were camouflaged), and the frequency of pink shells decreased. |
Natural Selection Challenge and Before You Go
Practice Time! Use the knowledge you learned from the lesson to complete the practice activities below.
Before You Go - You Need To Know
The following key points are from the explore section of the lesson. You must know the following information before moving to the next lesson. This is just a summary of the key points.
- Change over time is called: Evolution
- The 3 Types of Natural Selection are:
- Stabilizing
- Directional
- Disruptive
- Charles Darwin proposed that Natural Selection was a way to explain evolution.
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