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Evidence for Evolution A slide extravaganza… Types of evidence… 1. Evidence from the fossil record (dead things) Fossil formation Bones and shells undergo mineral replacement and are turned into rock Soft material either disappears, or leaves an impression in the earth (that turns to rock) A selection of fossils… Fossils show transitions The Archaeopterix -- between reptile and bird Scallops From early to modern horse (Living things show transitions too) Coelacanths - “the living fossil” Types of evidence… 1. Evidence from the fossil record Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy A. Homologous Structures Homo - logy Homologous structures have the same underlying forms Wing anatomy comparison And compared to our arm… Arm anatomy comparison B. Analogous Structures Ana - logy Analogous structures have a similar outward appearance (but different underlying forms) Types of evolution Convergent evolution Distantly related organisms evolve similar external features Divergent evolution A common ancestor gives rise to organisms that evolve for different environments Which goes with which? …. Homologous structures Analogous structures Convergent evolution Distantly related organisms evolve similar external features Divergent evolution A common ancestor gives rise to organisms that become more different with time. Which goes with which? Homologous structures Analogous structures Convergent evolution Distantly related organisms evolve similar external features Divergent evolution A common ancestor gives rise to organisms that become more different with time. C. Vestigial Structures Vestige - a left-over/ remnant Vestigial structures are evolutionary “leftovers” from an earlier ancestor The “dew” claw of a wild cat The human appendix Rabbit Fetal Human Adult Human Membranes in our eyes Hip bones in whales (Look at that “hand” too!) Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology Human embryo at 5 weeks Embryos… …can you guess which one is human? Embryos… …how about now? And now… Were you right? Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence Comparing DNA… Determining relationships DNA similarity between species is used to determine how closely related they are. This is in turn used to construct possible evolutionary trees. How closely related are these fellows? Mystery critter! (I’m not telling) Brown Bear …got your guess? Giant Panda An Evolutionary Tree This tree was constructed by looking at % similarity of DNA among “bears” …so why is he called a red panda? Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence 5. Behavior Behavioral similarities Duck and other bird mating dances How primates carry their young Fish swimming motions and salamander walks And on and on and on…. Types of evidence… 1. Evidence from the fossil record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence 5. Behavior Types of evidence… 1. Evidence from the Fossil Record 2. Comparative Anatomy 3. Comparative Embryology 4. Molecular Evidence 5. Behavior 6. Direct observation also known as microevolution Artificial selection Remember us? And look at us! And Natural Selection Hawaiian Rock Wallabies! The Beak of the Finch Biologists Peter and Rosemary Grant documented natural selection occurring in populations of finches on the Galapagos islands over a period of only 20 years! This generation to generation changes in the frequency of certain traits is called microevolution.