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EVIDENCE THAT SUPPORTS EVOLUTION. Pillar #1: The Fossil Record. What is a fossil?. The remains or evidence of an organism Fossilized bone, wood, shell, or dung Casts, imprints, or molds Amber or tar entrapments Imprints of footprints or borings. Fossil Facts.
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What is a fossil? • The remains or evidence of an organism • Fossilized bone, wood, shell, or dung • Casts, imprints, or molds • Amber or tar entrapments • Imprints of footprints or borings
Fossil Facts • Most are found in sedimentary rock. • The fossil record shows that life has changed over time. • The fossil record is very incomplete. • Fossils give us a glimpse into the morphology of organisms now extinct.
Interpreting Fossil Evidence • Relative Dating – the age of a fossil is estimated by comparing it to other fossils in rock layers • Rock layers form in order of age – the oldest layers are on the bottom
Interpreting Fossil Evidence • Radioactive Dating – using radioactive decay to assign absolute ages to fossils • A half-life is the length of time required for ½ of the radioactive atoms in a sample to decay
If 100 g of Carbon-14 decays until only 25 g of carbon is left after 11, 460 years, what is the half-life of carbon-14?
Thallium-208 has a half-life of 3.053 minutes. How long will it take for 120 g to decay to 7.5 g?
Gold-198 has a half-life of 2.7 days. How much of a 96g sample will be left after 8.1 days?
Homologous Structures • Structures that have similar characteristics but may or may not have similar functions. • Ex: forearms of vertebrates
Vestigial Structures • Structures that are diminished in size and/or function. • Ex: eyes of moles
Homologous & Vestigial structures give evidence of DIVERGENT EVOLUTION. • They suggest that descendents DIVERGED (became different) as the distance from the common ancestor increased.
Analogous Structures • Structures with the same function in organisms that are not closely related. • Ex: the wings of birds and the wings of insects. • Ex: thorns of the rosebush and the quills of the porcupine.
Analogous structures suggest CONVERGENT EVOLUTION. • Organisms did not descend from a common ancestor, they independently evolved similar adaptations to survive in similar environments.
Pillar #3: BiogeographyThe Geographic Distribution of Organisms
What is biogeography?The study of. . . • Where species live on earth and why • How organisms are adapted to their environment
Scientists study the • Morphology of Embryo • The fate of particular embryonic tissue
All organism have… • The same “Genetic Code” • 4 DNA nucleotides • Same 64 mRNA codons that code for the same amino acids • Ribosomes as the site of protein synthesis • ATP as the energy currency • Plasma membranes that consist of a phospholipid bilayer w/ imbedded proteins
Compare common proteins • Count and compare how many of the amino acids differ • Compare the nucleotide sequences of DNA • the closer the DNA sequences, the more closely related the organisms are.
Examples of OBSERVED Natural Selection • DDT Resistant Mosquitoes • Antibiotic Resistant Drugs • Darwin’s Finches