evidence for…. four types of evidence a. fossils b. transitional forms c. comparison of organisms...
TRANSCRIPT
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
• 3. Molds--”hollow” left after decay
• 4. Cast--filled in mold• 5. Traces--footprints, scat,
tools (often found in lava, sediments, ice)
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B. Transitional Forms
• Intermediate stages between old & new forms
• Ex: whales, birds/reptiles (Ex: archaeopterix), amphibians/fish
Evolution- How Do We Kn#1713B99
C. 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
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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)
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Embryo Comparison Pictures
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)
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Key Concepts
• Can you define………..?
• Fossils
• Vestigial and homologous structures
• Embryo
• Selective and artificial breeding
• DNA Comparision