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Transcript
Ultra Deep Field Here is what happened when professional astronomers pointed the Hubble Space Telescope at absolutely nothing and left it there, first for 10 days, and then for 11 days. Then they made the images into a 3-D presentation. Hang on to your seat! By the way, 13 billion light years are about equal to 880,000,000,000,000,000,000,000 (880 sextillion) miles. Be sure you have your sound on. ... and this was aimed at a blank spot in the sky? Hubble Ultra Deep Field 3D Evolution, Change and Diversity Adaptation and Change What does it mean to be “alive”? Characteristics of a living organism: Made of i) carbon, hydrogen, nitrogen, and oxygen ii) cells (organization of life processes) Able to iii) reproduce iv) grow and develop v) move vi) consume “food”, remove waste vii) maintain homeostasis Importance of Adaptation “Variety is the spice of life” True or False? What is the value of diversity? “All plants and animals, regardless of size, shape, or level of complexity, share certain characteristics.” Requirements for energy Basic cell structure and function Adaptation to a particular habitat Adaptations Inheritable changes in an organisms’ appearance behaviour structure mode of life that make the organism better able to survive in a particular environment The Theory of Evolution Attempts to explain why living organisms are so different in form and function while being similar in biochemistry & molecular makeup A process by which populations of living things change over a series of generations *Does not include individual change or development Evolution Project Theorists/Scientists 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. Lamarck Malthus Wallace Darwin Linneaeus Huxley Johanssen/Leaky Becquerel Wegener/Lyell Popes Mendel Scopes Hominids 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 13. 14. 15. Sahelanthropus tchadensis Ardipithicus ramidus A. anamensis A. afarensis A. africanus P. robustus P. boisei H. rudolfensis H. habilis H. ergaster H. erectus H. heidlebergensis H. archaic H. neandertalensis H. sapiens Evolution according to Lamarck Evolution Reversed? The Great Human Odyssey – CBC Documentary Series Evidence for Evolution Direct Evidence Fossil Record Fossil formation Carbon Dating Rapid Reproduction Bacteria produce many generations in a short period Indirect Evidence Geological Time Scale Biogeography Living Organisms Embryology Anatomy Physiology Biochemistry The Fossil Record A fossil is any trace of an organism that lived long ago Examples: Enclosed in resin (amber) Covered by sediment that eventually becomes rock Minerals filter into the body and turn to rock – cast/copy (petrification) Trace fossils – tracks or impressions left in soft sediment that later hardens Observe How Fossils Are Made Law of Superposition “Most sedimentary rocks are laid down in horizontal layers…increasing in age from top to bottom as long as the layers are not disturbed.” Fossils found in the undisturbed lower layers of sedimentary rocks are usually older and less complex than those found in upper layers. Scientist can use this rule to determine the relative age of many fossilized organisms. The Fossil Record cont’d… Geologists estimate age of sedimentary rock based on its thickness and location above or below other layers Relative age and radioactive dating used collectively helps determine both: the age of the Earth (4.5 billion years old) when the 1st life forms appeared (3.5 billion years ago) By piecing together fossil evidence according to age and similarity of structure, scientists have been able to study patterns of relationships among organisms = phylogeny evolutionary history Radiometric Dating (Geologic Time Scale) What is radiometric dating? Radioactive Dating Scientists calculate the ages of rocks and fossils accurately by measuring the decay of radioactive isotopes Carbon-14 Method used to date rocks and fossils younger than 50 000 yrs Ex) potassium-40; uranium-238; carbon-14 Carbon has 2 isotopes C14 turns into N14 C14 has a half-life of 5730 yrs Scientists know the approximate percentages the organisms start with; compare this to the present state How Do We Know Evolution Happens? Discussion Questions: 1. 2. 3. Gingerich discusses specifically only the whale fossils found in Egypt's "valley of the whales," but he points out that this now desert area was once a sea. Discuss the other kinds of fossils, and the types of rocks that must have been present for him to make this conclusion. Examine the cladogram of whales and their ancestors presented in this video. Note that this diagram does NOT show modern whales evolving from any specific fossil form, but form the common ancestors of known fossil species and modern animals. Discuss the important difference between this view of evolutionary history, and the old view -- which often attempted to identify specific fossils as THE ancestors of a living form. Discuss the similarities and differences between whale flippers and flukes and fish fins, using the scientific terms "homologous structures" and "analogous structures" in the discussion. What about mummies? Leonardo the mummified dinosaur Secrets of the Dinosaur Mummy http://watch.discoverychannel.ca/#clip93 695 http://watch.discoverychannel.ca/#clip93 694 Biogeography Discrepent Event: Animals that evolved from similar ancestors on different continents These ancestors had no way to get between continents at the time Too much of a coincidence? Plate tectonics and Pangaea… Biogeography Biogeography Common Ancestors… Conclusions… Life forms have become more complex over time while many simple life forms continue to exist Many fossils show strong similarities to existing organisms Disadvantage: fossil records are rare and incomplete Evidence from Living Organisms Embryology Anatomy Physiology Biochemistry Embryology The early stages of development show a number of relationships not obvious in the fully grown organisms. The more alike the development of 2 organisms, the more closely related they are. They probably inherited the same basic body plan from a common ancestor As development progresses their patterns become more different Comparative Anatomy (CBC Info Morning Science Corner, May 30, 2012) Homologous Structures Same basic structure and same pattern of early growth but may serve different functions Overall pattern of structure still resembles common ancestor Inherited structures become modified due to gradual adaptation to different environments The greater number of homologous structures two organisms share, the more closely related they are Homologous bones from human (I), dog (II), pig (III), cow (IV), tapir (V) and horse (VI): r — Radius, u — Ulna, a — Scaphoid, b — Lunare, c — Triquetrum, d — Trapezium, e — Trapezoid, f — Capitatum, g — Hamatum, p — Pisiforme Becoming Human Activity Divergent Evolution The presence of similar structures (e.g. bone structure) in very different animals leads scientists to believe that these animals had a common ancestor Divergent evolution is when two or more species evolve from one common ancestral species Analogous Structures Similar functions and, perhaps, appearances, but are quite different anatomically Indicates these organisms did not evolve from a common ancestor Convergent Evolution Animals that occupy a similar niche, regardless of ancestry, often evolve parts that function similarly The underlying structures may not be the same, but they serve the same purpose These are called analogous structures Vestigial Organs Structures that have no function in the living organism, but may have been used in the ancestors May be homologous with still-used structures in other related organisms As the organism adapts to a new lifestyle, it changes in form and behaviour, the once useful structure reduces size and function Biochemistry Chemical analysis show that similar organisms have similar chemical structures DNA molecules Amino acid sequences Certain proteins Ex) Cytochrome C Some scientists consider this the most compelling evidence for evolution Physiology Similarities among the functions of any of the parts of the organisms Example: digestion, waste excretion, hormone function, muscle movement Selective Breeding Within a population (breeding group) of organisms there is constant change over time Mutation and duplication of existing alleles can produce new alleles or genes Meiosis and fertilization can reshuffle alleles New alleles and genetic recombination are the source of evolution Humans direct and speed evolution by selecting only individuals with the most desirable traits to breed How does geography affect evolution? Biogeography = geographical distribution of organisms 6 regions separated by impassable barriers Each contains organisms unique to that region How is the distribution of organisms determined? Climate and other environmental factors affect distribution patterns over short periods (1000’s of years) Changes in the positions of the continents occur over longer periods (millions of years) Continental drift plate tectonics Pangea supercontinent 225 million years ago Convergent evolution = development of similar forms in geographically different areas in response to similar environments Curriculum Outcomes Evaluate current evidence that supports the theory of evolution. (316-2) Analyse and describe examples where scientific understanding was enhanced or revised as the result of the invention of a technology (116-2) Outline evidence and arguments pertaining to the origin development, and diversity of living organisms on Earth (316-4).