Transcript Evidence for Evolution

Evidence for…
Four Types of Evidence
• A. Fossils
• B. Transitional Forms
• C. Comparison of
Organisms
• D. Evolution Today
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A. Fossils
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Types of Fossils:
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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
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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
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• Evolution is
happening today, as
we speak!
• Ex: antibiotic resistant
bacteria, new strains
of viruses (flu)
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Key Concepts
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Can you define………..?
Fossils
Vestigial and homologous structures
Embryo
Selective and artificial breeding
DNA Comparision