What are the steps in natural selection? H ow is it involved in the evolution of organisms? - PowerPoint PPT Presentation

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What are the steps in natural selection? H ow is it involved in the evolution of organisms? PowerPoint Presentation
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What are the steps in natural selection? H ow is it involved in the evolution of organisms?

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What are the steps in natural selection? H ow is it involved in the evolution of organisms?
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What are the steps in natural selection? H ow is it involved in the evolution of organisms?

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  1. In a previous lesson you should have learned about the process of natural selection and how it explains why organisms evolve. • What are the steps in natural selection? • How is it involved in the evolution of organisms? Adaptation, natural selection and the evolution of species

  2. In this lesson we will be learning about the process of speciation • Success criteria • Explain the process of speciation Adaptation, natural selection and the evolution of species

  3. Speciation is the process that gives rise to new species. It incorporates the process of natural selection. It takes a long time. Adaptation, natural selection and the evolution of species

  4. Speciation involves the following : • A species is…..? • A group of organisms that can interbreed and produce fertile offspring. • The population making up the species is divided. • This might be geographically (mountains, rivers, • floods etc.), behaviourally or reproductively. • This isolates one group from another. Adaptation, natural selection and the evolution of species

  5. Different mutations occur spontaneously in the isolated populations. • Natural selection acts on the separate populations. • Those organisms best suited to the environment survive, reproduce and pass on their genes. • Different selection pressures allow different gene • pools to develop. Adaptation, natural selection and the evolution of species

  6. Each sub-population changes over time (long), it evolves. • Eventually the populations become genetically different. • The differences will be great enough to now be two distinct species. • If put back together the two species will not be able to reproduce and produce fertile offspring. Adaptation, natural selection and the evolution of species

  7. Adaptation, natural selection and the evolution of species

  8. Using the resources given to you try and explain the evolution of the Ratites (flightless land birds) Practical on animal behaviour using choice chambers Adaptation, natural selection and the evolution of species