evidence for evolution. fossil record shows gradual changes in organisms over time has some major...
Post on 20-Dec-2015
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Evidence for Evolution
Fossil Record
• Shows gradual changes in organisms over time
• Has some major gaps– Caused by:
• Conditions have to be just right for fossils to form• soft-bodied organisms can’t be fossilized (they just
get squished)• many fossils have been scattered and aren’t intact• some fossils destroyed by plate tectonics
Evolution of the Camel
Comparative Anatomy
• Homologous Structures: body structures with a common embryological origin
• Example: many animals have forelimbs with similar structures– Derived from the same structures in the
embryo– Suggests a common origin
• Analogous Structures: different structures in different groups of organisms undergo modifications to serve similar functions
• Example: wings of bats, birds, and butterflies
• These do not have a common evolutionary origin
Vestigial Structures
• Body parts which are considered evolutionary “leftovers”
• They are present but non-functional– Had a function in some ancient ancestor
• Examples in humans:– Tailbone – Shriveled up third eyelid– Goosebumps
• Pelvic bones in whales• Eyes in blind salamanders
Comparative Embryology
• Developing embryos of organisms from fish to humans look almost identical
Fishsalamander
tortoise chicken pigcow
rabbithuman
Biochemistry
• ALL organisms have the same DNA bases of T, A, G, C
• Organisms with more similar DNA are more closely related
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