Darwin's Theory of Evolution: Natural Selection and Evidence, Slides of Theory of Evolution

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Ch. 15 Evolution

p. 418 - 441

15.1 Darwin’s Theory of

Natural Selection

p. 418 – 422

Main Idea

! Charles Darwin developed a theory of evolution based on natural selection.

What was the primary mission of

the Beagle?

! To survey the coast of South America

What did Darwin notice as he

made collections of the animals

in the Galapagos Islands?

! He noticed that the different islands seemed to have their own, slightly different varieties of animals

What is an ornithologist?

! A scientist who studies birds

What did Darwin hypothesize?

! New species could appear gradually through small changes in ancestrial species

What are two examples of when

artifical selection occurs?

! When breeding dogs ! When new strains of crops

What are the four basic principles

of Darwin’s theory?

! 1. Individuals in a population show differences, or variances ! 2. Variations can be inherited ! 3. Organisms have more offspring than can survive on available resources ! 4. Variations that increase reproductive success will have a greater chance of being passed on

What did Darwin reason from his

theory of natural selection?

! Given enough time, natural selection could modify a population enough to produce a new species

Visualizing Natural Selection:

give an example of how a sunflower population exhibits the for principles of natural selection ! Variation – some sunflowers are taller than others ! Heritability – tall sunflowers produce tall sunflowers; short sunflowers produce short sunflowers ! Overproduction – each sunflower has hundreds of seeds, most of them will not germinate ! Reproductive advantage – shorter sunflowers reproduce more successfully

Evolution

! Cumulative changes in groups of organisms through time

15.2 Evidence of Evolution

p. 423-

Essential Question