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1 The Theory of Natural Selection Biology I
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2 I. Early Biology Scientists knew that organisms had changed Fossil evidence Age of the Earth
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3 Lamarck Changes from simple to complex Organisms want to adapt or change Acquired characteristics were inherited (passed on)
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4 Lamarck Later disproved
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6 II. Darwin At 21, took a job as a naturalist on the HMS Beagle Collected specimens, took notes of different organisms
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7 His voyage:
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8 II. Darwin Sailed to Galapagos Islands All new species, but similar to those found elsewhere
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9 Finches most famous Had slightly different beaks from island to island Differed by their diet
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10 II. Darwin Darwin 22 years developing theory of natural selection Pressured into publishing by Wallace Published On the Origin of Species by Natural Selection
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11 III. Natural Selection 4 Requirements 1. Variation exist 2. Differential Reproduction 3. Heredity Best suited survive and reproduce 4. Lots of Time
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12 1. Variation Variations exist –Color, size, speed, etc. Variations are genetically linked
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13 2. Differential Reproduction Organisms produce more offspring than can survive –creates competition and Survival of the Fittest = Only the best are going to survive
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14 Heredity Beneficial variations survive, pass traits to offspring Passed through DNA
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15 Natural Selection Over time variations become more frequent in population Results in population being different than ancestors
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16 Evolution Evolution is the change in a population over time Natural Selection - Remember the Giraffe? How did it get the long neck?
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17 Evidence of Change Fossil Record Anatomy & Physiology Embryology Biochemistry
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18 Fossils Remains or traces of living organisms
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19 Physiology Mimicry-An adaptation Enables one species to resemble another species. Ex.-harmless species looks like a harmful one, good tasting vs. bad tasting.
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22 Camouflage-An adaptation A species blends in with its environment to avoid predators. Ex.- peppered moth, leaf frog
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23 Anatomy- Homologous Structures Common evolutionary origin. Similar in arrangement or function or both. Example: forelimbs of a whale, a crocodile and a bird wing.
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25 Anatomy- Analogous Structures No common evolutionary origin, but similar in function. Wings of a bat and wings of a butterfly.
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27 Anatomy- Vestigial Structures No function now but was probably useful to an ancestor. Ex. A whale has leg bones, a snake has leg bones
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29 Embryology Earliest stage of growth and development Embryos of a fish, a chicken, a pig, a cow, a rabbit, and a human are almost identical. They all have gill slits and a tail.
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31 Biochemistry Comparisons of DNA and RNA Now monera (prokaryotes) is divided into two separate kingdoms based on their biochemistry.
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32 V. Mechanisms of Evolution Genetic Drift Gene Flow Artificial Selection Natural Selection Sexual Selection
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33 Genetic Drift Change in allele frequency by CHANCE
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34 GENE FLOW Bottleneck effect Founders effect 34
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35 Gene Flow Change in allele frequency as a result of MIGRATION
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36 Sources of Variation GENE FLOW moves genes among populations SEXUAL REPRODUCTION introduces new gene combinations Random MUTATIONS in DNA lead to the formation of new alleles (sound familiar?)
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37 Mutations Can be beneficial, neutral, or harmful for the organism Only mutations in gametes are inherited by offspring
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38 Bell: What is the difference between Analagous structures, Homologous Structures, and Vestigial Structures? What are the 4 requirements of Natural Selection? 38 AGENDA Intro to Classification Natural Selection Today Antibiotics
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