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Evidence for…. Four Types of Evidence. A. Fossils B. Transitional Forms C. Comparison of Organisms D. Evolution Today. A. Fossils. Types of Fossils: 1. Actual remains --wolly mammoth, shells 2. Petrification --organic substances replaced by minerals
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Four Types of Evidence • A. Fossils • B. Transitional Forms • C. Comparison of Organisms • D. Evolution Today
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)
B. Transitional Forms • Intermediate stages between old & new forms • Ex: whales, birds/reptiles (Ex: archaeopterix), amphibians/fish Evolution- How Do We Kn#1713B99
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
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
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
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
C. Comparison of Organisms cont… • Selective Breeding -humans have bred dogs over hundreds of years to obtain new breeds; seedless oranges
D. Evolution Occurs Today • Evolution is happening today, as we speak! • Ex: antibiotic resistant bacteria, new strains of viruses (flu)
Key Concepts • Can you define………..? • Fossils • Vestigial and homologous structures • Embryo • Selective and artificial breeding • DNA Comparision