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Published byQuentin Job Edwards Modified over 9 years ago
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Natural Selection and Evolution!
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Why two types of clover? What advantages does the striped clover have? The plain? How does cyanide help/hurt these plants in different habitats?
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Organisms have variation Same species (Trifolium repens), different characteristics Variation = differences among individuals of one species; different forms of same trait (ex: eye colors)
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Variation helps organisms adapt Adaptation = inherited characteristic, increases an organism’s chance for survival Fitness = ability of an individual to survive and reproduce in its environment Which clover is more “fit?” Why?
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Variation allows for Selection Humans and nature “choose” which organisms win and get to procreate Artificial selection = human select most useful variations, allow those to reproduce ex: race horses - what trait would be selected for? ex: broccoli and other veggie friends
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The struggle for existence Resources are limited, so only some can survive Natural Selection = individuals better adapted to their environment survive, reproduce, and pass on their genes AKA “survival of the fittest” leads to change over time (EVOLUTION!)
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Natural Selection - Ex: Darwin’s Finches Beak size and shape vary - all descended from common ancestor but changed over time
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Evolution by Natural Selection Descent with modification = over time, natural selection produces organisms with differences from their ancestors Different food sources, habitats, body parts, behaviors Implies that living things are all related, have a common ancestor (common descent)
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Common Descent - one ancestor in the past Phylogenetic tree - distance between organisms is directly related to differences in genes (short distance = few differences, long = many)
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