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Published byClare McKinney Modified over 9 years ago
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Natural Selection & Change over time
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Charles Darwin British naturalist Sailed on the HMS Beagle around the world Collected and recorded all the different species and fossils he came across Wanted to explain biodiversity
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Darwin at the Galapagos The Galapagos islands have many different biomes – Hot and dry like the desert – Rainy and full of plants Within each biome, Darwin would find different species that were suited to live there
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Darwin at the Galapagos Noticed that several organisms had differences depending on where they lived
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Darwin’s Finches Uses beak to crush seeds Uses twigs to probes insects in trees Probes in holds in trees for insects Uses beak to grasp insects
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Darwin’s Observations Organisms tend to over produce Variation exists within a population
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Darwin’s Conclusion Darwin summarized his conclusions in The Origin of Species – Common Descent with Modification – Evolution by Natural Selection
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Back to the giraffe Ancestors of giraffes had slight variations The ones with slightly longer necks survived longer and reproduced more The ones with shorter necks eventually died out
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Artificial Selection
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Evidence The fossil record
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Evidence Biogeography
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Evidence Homologous body structures Vestigial organs
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Evidence Embryology
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Molecular Homologies
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Theory of the origin of life
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Early Earth Earth is about 4.6 billion years old Lots of lightning Early atmosphere was full of poisonous gases, water vapor, and no oxygen
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Habitable Earth About 3.8 billion years ago, Earth cooled enough for water to remain liquid
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Theory of the origin of life Miller & Urey (1950s) Simulated early Earth’s atmosphere Added a spark of electricity to simulate lightning They made… AMINO ACIDS!
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4 Step process for the origin of life
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The First Eukaryotes About 2 million years ago, eukaryotes evolved (endosymbiosis)
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