22.2 Darwin's Theory of Evolution.notebook

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March 07, 2017

22.2 Darwin: Descent with modification by natural selection explains adaptations

A. Darwin's work1. adaptation

a. inherited traits that increase an organism's survival & reproduction

2. natural selectiona. process in which organisms with certain inherited traits tend to survive more & reproduce more because of the traits

B. The Origin of Species1. Descent with Modification

a. unity of all life is due to the decent of all organisms from an ancestor that lived in the remote past

22.2 Darwin's Theory of Evolution.notebook

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March 07, 2017

2. Natural Selectiona. Darwin's Observations

#1: members of a pop. vary in their traits#2: all species can produce more offspring than the

environment can support & many of these offspring fail to survive

b. Darwin's Inferences#1: Individuals whose traits give them a higher

chance of surviving and reproducing tend to leave more offspring than others

#2: This unequal ability of individuals to survive & reproduce will lead to a build up of favorable traits in a pop. over generations

c. Key points about N.S.1. Populations evolve, not individuals2. NS can amplify or distinguish only heritable traits

that differ among the individuals in a pop.3. Environments change from place to place & time to

time.

22.2 Darwin's Theory of Evolution.notebook

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March 07, 2017

Variation in a Population