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Intro to Evolution Darwin and Natural Selection Biology AP Todeschini Darwin’s Ideas • When Darwin published The Origin of Species in 1859 he was not the first to suggest the idea of evolution. • He merely suggested a mechanism under which it would function: natural selection • He suggested that the diversity of life resulted from descent with modification from previous ancestors. Darwin’s Influences Scientists that influenced Darwin • Carolus Linnaeus, the founder of taxonomy, said every creature had a purpose. • Thomas Malthus predicted that populations were all grow exponentially and then crash. • Paleontology, the study of fossils, was largely developed by French scientist Georges Cuvier Scientists that influenced Darwin Lamarck was correct in identifying that traits are passed on but didn’t know they must be genetic in nature NOT acquired. • Geologists James Hutton and Charles Lyell perceived that changes in Earth’s surface can result from slow continuous actions still operating todayVERY OLD EARTH! • Lamarck hypothesized that species evolve through use and disuse of body parts and the inheritance of acquired characteristics Darwin’s Journey • After graduating with a degree in theology, he took an unpaid position as naturalist and companion to Captain Robert FitzRoy for a 5-year around the world voyage on the Beagle Darwin’s Journey • He observed adaptations of plants and animals that inhabited many diverse environments, most influential stop being the Galapagos Island “The natural history of these islands is eminently curious, and well deserves attention. Most of the organic prof\ductions are aboriginal creatures, found nowhere else, there is even a difference between the inhabitants of the different islands; yet all show a marked relationship with those of America, though separated from that continent by an open space of an ocean, between 500 and 600 miles in width. …Hence, both in space and time, we seem to be brought somewhere near to that great fact- that mystery of mysteries- the first appearance of new beings on this earth.” Darwin (Journal entry) What did Darwin See? • Giant land tortoises, will great diversity oh shells, neck length • Sea iguanas that eat algae, only ones on planet • Finches, finches, finches! The Origin of Species • Darwin developed two main ideas: • Descent with modification explains life’s unity and diversity • Natural selection is a cause of adaptive evolution • Natural selection acts on adaptations organisms have • In the Darwinian view, the history of life is like a tree with branches representing life’s diversity How it Works 1. Overproductions of offspring (Malthus) -not all offspring will survive, there will be competition and varying chances of survival How it Works 2. Variation among individuals - no two organisms are exactly the same How it Works • 3. Competition for limited resources • Struggle for existence is real! How it Works • 4. Successful competitors survive, reproduce, & pass on their traits • The more traits you pass on the higher your Fitness! How it Works 5. Repeat 1-4 for millions of years and life will adapt to the environment. Artifical Selection • Darwin was influenced by the artificial selection he saw happening because of the “fitness”determined by human wants and needs. https://www.youtube.com/watch?v=WseH479iOM0 Pesticide/Antibiotic Resistance • Life will always adapt if it can. • Spraying of pesticides kills all the pests who are not resistant. • Because of variation present some pests will have a natural defense and survive to reproduce. • Similar mechanisms drive antibiotic resistance in bacteria and viruses.