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How did such tremendous diversity of life come to exist on this planet?. Evolution. Each organism is unrelated and is created independently Life evolved many times. All life shares common ancestry - all life is related Life evolved once only. What Did Darwin Do?. Two key things:

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How did such tremendous diversity of life come to exist on this planet?

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Evolution
Evolution this planet?

Each organism is unrelated and is created independently

Life evolved many times

All life shares common ancestry - all life is related

Life evolved once only

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What did darwin do
What Did Darwin Do? this planet?

Two key things:

1. He provided evidence for evolution

2. He proposed a theory to explain the mechanism by which evolution occurs

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Evolution1
Evolution this planet?

Darwin's definition: descent with modification.

,

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Darwin s evolution
Darwin’s Evolution this planet?

  • Organisms have changed overtime

  • All organisms share common ancestors

    3. Change is gradual

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1 fossil record change over time
1. Fossil Record – Change over time this planet?

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2. Shared Structures – this planet? Common Ancestry

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3. Similarities Between Embryos – Change is gradual this planet?

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The mechanism for evolution
The Mechanism for Evolution this planet?

Natural Selection

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Natural selection
Natural Selection this planet?

1. There is a "struggle" (metaphorically) to survive and reproduce (organisms produce potentially more offspring that can possibly survive)

2. Organisms show variation in characters that influence their success in this struggle for existence.

3. Parents possessing certain traits that enable them to survive and reproduce will contribute disproportionately to the offspring that make up the next generation.

4. The population in the next generation will consist of a higher proportion of individuals that possess whatever adaptation enabled their parents to survive and reproduce.

5. Overtime the population will become adapted to the environment

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Requirements for natural selection
Requirements for Natural Selection this planet?

  • 1. Heritable variation for some trait

  • 2. Differential survival and reproduction associated with the possession of that trait.

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Antibiotic resistance an example of modern day evolution by natural selection
Antibiotic resistance – an example of modern day evolution by natural selection

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Variation in population by natural selection  over production of offspring  competition between offspring  best adapted survive and reproduce  favourable characteristics passed onto next generation

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Why haven’t polar bears got white noses? by natural selection

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www.thescienceteacher.co.uk by natural selection


4 genetic changes
4. Genetic Changes by natural selection

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Darwin s theory of evolution by natural selection
Darwin's Theory of Evolution by by natural selection Natural Selection

  • Individual characteristics of an organism are vitally important for its ability to survive and to breed

  • Individuals of a given species vary in many characteristics

  • Individuals produce more offspring than can survive i.e. there is competition

  • Only a small proportion of offspring will therefore survive. If those characteristics which help the oranThese individals that survive

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Did humans evolve from chimpanzees
Did humans evolve from chimpanzees? by natural selection

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www.thescienceteacher.co.uk by natural selection


www.thescienceteacher.co.uk by natural selection


Evidence for evolution
Evidence for Evolution by natural selection

1.Fossil evidence shows the course of evolution through time

2. Similar structures are shared by many organisms

3. Comparative embryology (looking at similarities between developing embryos of different species)

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