CH 13---Evolution and Natural Selection

CH 13---Evolution and Natural Selection - Evolution and...

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Unformatted text preview: Evolution and Evolution Natural Selection Natural Early Beliefs Species created and “placed” Fixed, unchanging Earth = 6,000 years old 1700’s & 1800’s – this view was challenged Giraffes in Africa Charles Darwin Voyage of The Beagle Galapagos Islands Darwin’s Finches Ground finch – large beak for cracking seeds on the ground Small tree finch – uses beak to grasp insects Woodpecker finch – uses tools to hunt for termites and other insects Darwin Wallace Published The Origin of Species 1859 “Descent with modification” by means of Natural Selection Conditions for Natural Selection: • Observation 1: INDIVIDUAL VARIATION • Observation 2: OVERPRODUCTION e.g. green and and brown beetles brown e.g. some are eaten, starved, frozen, diseased unmated……. Heredity of Heredity Inference: DIFFERENTIAL REPRODUCTIVE for those • traits traits that survive. SUCCESS •End Result: Eventually the advantageous trait dominates…… Darwinian Fitness… and reproduction and of fertile offspring of Survival of the fittest? FITNESS = SURVIVAL & REPRODUCTION = an organism’s contribution of genetic information to future generations Evolution = a change in the genetic makeup of a population over time (change in frequency of alleles) Alleles – good or bad? It depends!! THE ENVIRONMENT!!!! Evolutionary Adaptation Tree mantid ­ Trinidad Leaf mantid – Costa Rica Flower mantid ­ Malaysia The Modern Synthesis Julian Huxley – 1942 Mendelian genetics Darwinian evolution Microevolution Macroevolution Populations Evidence for Evolution Biogeography Biogeography Evidence for Evolution Biogeography Comparative morphology Comparative Morphology Homology Evidence for Evolution Biogeography Fossil record Comparative morphology Fossil Record Evidence for Evolution Biogeography Fossil record Comparative morphology Comparative embryology Comparative Embryology Evidence for Evolution Biogeography Fossil record Comparative morphology Comparative embryology Molecular biology Molecular Biology Evidence for Evolution Biogeography Fossil record Comparative morphology Comparative embryology Molecular biology Artificial selection Artificial Selection Evidence for Evolution Biogeography Fossil record Comparative morphology Comparative embryology Molecular biology Artificial selection Mechanisms of Evolution Genetic Drift Mechanisms of Evolution Genetic Drift – Bottleneck effect Mechanisms of Evolution Genetic Drift – Bottleneck effect – Founder effect Mechanisms of Evolution Genetic Drift Gene Flow – Bottleneck effect – Founder effect Mechanisms of Evolution Genetic Drift Gene Flow Mutations – Bottleneck effect – Founder effect Mechanisms of Evolution Genetic Drift Gene Flow Mutations – Bottleneck effect – Founder effect Natural Selection Outcomes of Natural Selection Directional selection Outcomes of Natural Selection Directional selection Diversifying selection Outcomes of Natural Selection Directional selection Diversifying selection Stabilizing selection Stabilizing selection 20 percent of population 100 70 15 50 30 20 10 10 percent mortality percent mortality 5 5 3 2 1 2 3 4 5 6 7 8 9 10 11 Human birth weight (pounds) Selection Environmental selection • Environmental selection Sexual selection • Sexual selection Sexual Selection ...
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