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Change Through Time By: Susan Karikas How did we get here from there? • Mechanisms of evolution – Millions of different organisms inhabit our planet – Species reproduce their own types – Since the beginning of time organisms have changed and continue to change Who thought of this stuff? • Jean Baptiste de Lamarck – Early evolution theorist (1809) – French scientist hypothesized that offspring inherit traits that their parents developed throughout their life. • Weight lifters develop muscle through hard work and not inheriting from their parents Charles Darwin’s visit to the Galapagos Islands • At the age of 22, Charles Darwin sailed on the HMS Beagle to South America • He observed and recorded facts about plants, animals, and fossils – Giant cactuses, 13 species of finches, and huge land turtles • He collected specimens – For 20 years he studied his specimens to come up with his hypothesis Principles of Natural Selection • Organisms with traits best suited to their environment are more likely to survive and reproduce • Five factors involved in natural selection – Organisms produce more offspring than can survive; variations exist within species; these variations are passed on to offspring; some variations allow members of a population to survive; over time these helpful variations make up more of a population Adaptation and Variation • A variation is an inherited trait that makes one member different from another of the same species. Variations result in mutation of one’s DNA. – An example could be as simple as the shape of one’s hairline or as complex as fruits without seeds • Some variations are more helpful than others • Variations result in adaptations Adaptations • An adaptation is any variation that makes an organism better suited to its environment – Camouflage is an adaptation that allows an organism to blend into its environment and thus have a better chance of surviving and passing on helpful traits to its offspring How fast does evolution occur? • Scientists have different hypotheses on this issue. – Many believe evolution occurs over millions of years • Gradualism – Others believe change occurs more quickly • Punctuated equilibrium • Evidence supports both models Models of change: Gradualism and Punctuated Equilibrium • Gradualism states that evolution is a slow, steady and ongoing process – Change of one species to another – Intermediate form of all species • Punctuated Equilibrium states that evolution can occur more quickly through mutations in DNA – An example of this model is bacteria that is destroyed by antibiotics How do we know this is true? • Fossil evidence – Any evidence of life from an earlier geological time – Imprints of a leaf, feather, or organism in a rock – A piece of wood or bone – An organism frozen in ice – An insect or organism trapped in amber (think Jurassic Park)