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Evidence for…

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  1. Evidence for…

  2. Four Types of Evidence • A. Fossils • B. Transitional Forms • C. Comparison of Organisms • D. Evolution Today

  3. A. Fossils Types of Fossils: • 1. Actual remains--wolly mammoth, shells • 2. Petrification--organic substances replaced by minerals • 3. Molds--”hollow” left after decay • 4. Cast--filled in mold • 5. Traces--footprints, scat, tools (often found in lava, sediments, ice)

  4. B. Transitional Forms • Intermediate stages between old & new forms • Ex: whales, birds/reptiles (Ex: archaeopterix), amphibians/fish Evolution- How Do We Kn#1713B99

  5. Comparison of Organisms--similar structures which give support for evolution • Homologous Structures-- structures that are biologically similar in different species, but have changed through time • Ex: fin, arm, wing, hand

  6. C. Comparison of Organisms cont… • B. Vestigial Structures--structures that are inherited but are now unused (without function) • Ex: tail bone & ear muscles in humans, whale pelvis, hip & leg bones in a snake

  7. C. Comparison of Organisms cont… • Embryo Comparisons --Similar embryonic development Ex: vertebrate embryos look very similar (all have gill pouches & tails) YouTube - What Can Embr#1713AE9

  8. Embryo Comparison Pictures

  9. C. Comparison of Organisms cont… • DNA Comparison -all living organisms have DNA with the same 4 bases (A, T, C, G) • All have similar amino acids (only 20 different a.a.) • Chimps & humans have 98.6% DNA relatedness

  10. C. Comparison of Organisms cont… • Selective Breeding -humans have bred dogs over hundreds of years to obtain new breeds; seedless oranges

  11. D. Evolution Occurs Today • Evolution is happening today, as we speak! • Ex: antibiotic resistant bacteria, new strains of viruses (flu)

  12. Key Concepts • Can you define………..? • Fossils • Vestigial and homologous structures • Embryo • Selective and artificial breeding • DNA Comparision