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Unit V - Evolution

Unit V - Evolution. I. Scientific Theories – Laws – Facts - Hypothesis A. Fact – in science, an observation that has been repeatedly confirmed 1. i.e. objects fall when dropped 2. i.e. humans have 46 chromosomes. B. Hypothesis

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Unit V - Evolution

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  1. Unit V - Evolution

  2. I. Scientific Theories – Laws – Facts - Hypothesis A. Fact – in science, an observation that has been repeatedly confirmed 1. i.e. objects fall when dropped 2. i.e. humans have 46 chromosomes

  3. B. Hypothesis 1. a testable statement about the natural world that can be used to build more complex inferences and explanations 2. “IF…THEN…”

  4. C. Law 1. a descriptive generalization about how some aspect of the natural world behaves under stated circumstances 2. i.e. the path of each planet around the sun is an ellipse with the sun at one focus (Kepler’s First Law of Planetary Motion) http://www.aerospaceweb.org/question/astronomy/solar-system/solar-system.jpg

  5. Newton’s First Law – An object at rest remains at rest and an object in motion maintains its velocity unless it experiences an unbalanced force. Newton’s Second Law – The unbalanced force acting on an object equals the object’s mass times its acceleration. Newton’s Third Law – For every action force, there is an equal and opposite reaction force.

  6. Law of Conservation of Mass - mass cannot be created or destroyed Law of Conservation of Energy - energy cannot be created or destroyed http://www.google.com/imgres?imgurl=http://www.wildonesonline.faketrix.com/content/pictures/original/amazing-roller-coaster-picture.jpg&imgrefurl=http://www.wildonesonline.faketrix.com/picture-4-roller-coaster-amusement-park.htm&h=137&w=103&sz=61&tbnid=pnAXTnxGYjkJ:&tbnh=137&tbnw=103&prev=/images%3Fq%3Droller%2Bcoaster%2Bpics&sa=X&oi=image_result&resnum=1&ct=image&cd=1

  7. D. Theory 1. a broad and comprehensive statement of what is believed to be true, supported by considerable experimental evidence resulting from many tests of related hypotheses 2. in everyday speech, people use the word theory when they are talking about a hunch or a guess 3. really they should use the word “hypothesis”

  8. 4. Examples of Scientific Theories a. atomic theory – all matter is made of atoms b. cell theory – all living things are composed of cells c. theory of gravitation – all matter attracts other matter d. theory of plate tectonics – Earth’s crust is made of plates which move over time

  9. e. Kinetic Theory explains the three states of matter 1) all matter is made of atoms and molecules that act like tiny particles 2) these tiny particles are always in motion. The higher the temperature, the faster the particles move 3) at the same temperature, more massive particles move slower than less massive particles

  10. f. Theory of Evolution 1) species change over time 2) the best explanation of biological diversity on Earth

  11. 5. Theories… a. are well substantiated explanations b. are internally consistent and compatible with the evidence c. are firmly grounded in and based upon evidence d. have been tested against a diverse range of phenomena e. explain a wide variety of phenomena

  12. 6. Theories are not absolute – as we do more experiments and learn more about the world around us, our explanations can change

  13. 7. How do scientists arrive at a theory? a. make observations b. try to explain these observations c. make predictions d. use models e. test proposed predictions, etc. f. communicate g. revise predictions/explanations h. test revisions i. Test validity and reliability

  14. 8. Scientific Method of Investigation a. Identify the Problem b. Research c. Develop Hypothesis d. Design Experiment e. Conduct Experiment/Make Observations f. Draw Conclusions g. Communicate Findings

  15. II. The Mystery of Life’s Origin A. Divine Creation 1. relating to a God or Gods 2. Cannot be proven by science B. Spontaneous Origin 1. life developed by itself through natural chemical and physical processes 2. Primordial Soup Model a. large amounts of organic molecules were in a “warm little pond” b. eventually formed living things

  16. 3. the Bubble Model a. processes took place within bubbles on the ocean’s surface C. Extraterrestrial 1. origin outside of the Earth

  17. III. Evolution by Natural Selection A. Voyage of the Beagle

  18. B. Darwin’s Theory 1. individual organisms differ – some traits are heritable 2. organisms produce more offspring than can survive 3. because more are produced than can survive, they compete for resources

  19. 4. some organisms possess advantages that help them survive and reproduce over other organisms – this causes species to change (natural selection) 5. today’s species have descended with modifications from ancestral species

  20. IV. Evidence for Evolution A. Fossils 1. traces of once living organisms 2. Imprint a. a film of carbon remains after the other elements of an organism have decayed Ammonites in matrix - http://www.fossils-facts-and-finds.com/; imprint dragonfly - http://www.units.muohio.edu/dragonfly/skeletons/

  21. 3. Mold a. an impression of the shape or track of an organism 4. Cast a. sediments fill in the cavity left by a fossil mold Trilobite cast and mold pair - http://scientificsonline.com/product.asp?pn=3081439&bhcd2=1205787201

  22. B. Geographic Distribution of Living Species

  23. B. Geographic Distribution of Living Species http://en.wikipedia.org/wiki/Lion; http://en.wikipedia.org/wiki/Jaguar; http://en.wikipedia.org/wiki/Cougar

  24. C. Homologous Structures 1. structures that are embryologically similar

  25. D. Vestigial Organs 1. structures or organs that seem to have no useful purpose 2. examples a. human tailbone b. snakes with pelvic and limb bones http://en.wikipedia.org/wiki/Ostrich

  26. E. Embryological Development 1. embryos of some species develop almost identically during early stages

  27. E. Embryological Development http://www.pbs.org/wgbh/evolution/library/04/2/pdf/l_042_03.pdf

  28. F. Biochemical 1. same complex biochemical compounds (ie- DNA) govern same functions in vastly different organisms 2. unlikely that almost identical compounds would have evolved independently in widely different organisms

  29. Kit fox - http://www.americazoo.com/goto/index/mammals/247.htm; red fox - http://animals.nationalgeographic.com/animals/mammals/red-fox.html V. Patterns of Evolution A. Divergent Evolution 1. two or more related species becoming more and more dissimilar 2. ie – red fox (farmlands and forest) vs. kit fox (plains and deserts) 3. adapted to their environment

  30. B. Convergent Evolution 1. unrelated species become more and more similar as they adapt to the same kind of environment 2. ie – cactus (US) vs euphorbia (African desert) Euphorbia (rt) - http://www.desert-tropicals.com/Plants/Euphorbiaceae/Euphorbia_abyssinica.html; cactus (left) - http://www.desertusa.com/july96/du_saguaro.html

  31. C. Coevolution 1. the joint change of two or more species in close interaction 2. ie – birds and flowers http://en.wikipedia.org/wiki/Hummingbird

  32. VI. Genetic Equilibrium A. Species 1. a group of individuals that look similar and whose members are capable of producing fertile offspring in the natural environment B. Hybrid 1. the offspring of two morphologically dissimilar organisms

  33. C. Variation of (polygenic) Traits in a Population 1. Bell Curve http://classes.kumc.edu/sah/resources/sensory_processing/images/bell_curve.gif

  34. Phenotypes for Single-Gene Traits

  35. Polygenic traits -traits governed by more than one set of alleles

  36. D. Hardy-Weinberg Principle 1. = Genetic Equilibrium 2. a population will remain in genetic equilibrium IF: a. no mutations occur b. Individuals neither enter nor leave the population through migration c. the population is large d. individuals mate randomly e. natural selection does not occur ** for evolution to occur, something must upset genetic equilibrium

  37. E. Changes in Genetic Equilibrium 1. Natural Selection a. organisms with favorable traits or adaptations survive and reproduce at greater rates than those without these traits http://animals.nationalgeographic.com/animals/mammals/zebra.html

  38. b. Directional Selection 1) proceeds in one direction

  39. c. Stabilizing Selection 1) eliminates the extremes

  40. d. Disruptive Selection 1) selects against the average

  41. e. Artificial Selection 1) nature provided the variation, and humans selected those variations that they found useful http://soilcrop.tamu.edu/photogallery/cornsorghum+/pages/corn%20ears.htm

  42. 2. Migration a. movement of organisms into or out of a population http://www.pgc.state.pa.us/crep/lib/crep/two_white_tailed_deer.jpg

  43. 3. Genetic Drift a. the change in gene frequency b. result of the laws of probability and chance

  44. 4. Isolation a. separation of populations into groups that no longer interact b. rivers, mountains, and canyons 5. Mutation (GCUCCU) 6. Nonrandom Mating a. mating with like/self b. decrease genetic variation c. increase homozygous traits http://www.hawaiipictures.com/pictures/oahu/mountains4-1.jpg

  45. The End

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