Transcript How Does Evolution Happen?

How Does Evolution Happen?
Chapter 10, section 2
Charles Darwin
• Let’s read a little background on Charles
Darwin…
• See pages 306-307
 List 5 important facts about Darwin’s life
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Ideas about Breeding
• Trait = form of an inherited characteristic
• Selective Breeding = humans choose plants
or animals for breeding based on a desired
trait
Ideas about Population
• Species can produce many offspring but
only those with enough resources (food,
water, etc.) will survive long enough to
reproduce
• Those with traits that help them survive
will pass on those helpful traits to their
offspring
Ideas about Earth’s History
• The Earth is very old and therefore
there has been plenty of time for an
organism to change slowly over time.
Darwin’s Theory of Natural
Selection
• Evolution happens by natural selection
• Natural selection = The process by
which organisms with favorable traits
survive and reproduce at a higher rate
than organisms without the favorable
trait
4 steps to Natural Selection
1. Overproduction = more offspring are born
than can survive
2. Inherited Variation = each individual has its
own set of traits (some favorable, some not)
3. Struggle to Survive = Only some individuals
live long enough to reproduce
4. Successful Reproduction = Those best
adapted reproduce and have offspring that
survive
Natural Selection Example
(pg. 310)
What Darwin didn’t Know…
• Darwin was unaware of the “how”:
• Research has given us more information
 DNA (Watson and Crick)
 Genetics (Gregor Mendel)