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Darwin and Natural Selection
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Charles Darwin (born 1809) -sailed on the HMS Beagle for 5 years studying organisms around the world (many in the Galapagos) -Noticed similarities amongst organisms around the world (wanted to know how)
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Artificial Selection Noticed that humans grow crops and breed animals to get the most useful traits in offspring (ex. cows with more milk, biggest vegetables,) -called this artificial selection.
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Charles Darwin -Concluded that natural selection can occur too .
-1. organisms in a population vary in traits -2. these traits can be passed on to offspring. -3. more are born than the environment can support -4. the ones with the best traits live to pass them on Ex. Sharp teeth in sharks
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Natural Selection -natural selection -change in populations traits over time (must be heritable [in genes]) -selective pressure – factor that makes a trait favorable (predator, habitat, food source, etc). -fitness level- how equipped an organism is for survival and reproduction
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Adaptations -inherited traits that increase organisms’ chances of survival (color, claws)
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Structural Adaptations
-physical structures that increase an organism’s fitness level
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Coloration Camouflage- blend in with surroundings
Mimicry- imitate other organisms
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Ornamental -structures that attract mates
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Physiological Changes in the body to increase fitness level (ex. immunity)
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Behavioral -behaviors that increase fitness
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