Page 125 - Science Course 3 (Book 1)
P. 125
Mo3-L3b: How Are Organism Related?
Key Concept Molecular data indicate that whales and porpoises
are more closely related to hippopotamuses than
How Are Organisms Related? they are to any other living species.
How is molecular biology use to determined
relationship among species?
Even-toed
hoofed mammals
Whale and
Dolphin
Hippopotamuses Mammals
Other
mammals
Present 25 50 75
Day
Millions of Years Ago (mya)
The Study of Evolution Today
New evidence supporting the theory of evolution by
natural selection is discovered nearly every day, but
scientists debate some of the details.
New fossils that have features of species that lived
both before them and after them help scientists
study more details about the origin of new species.
Original Population Random Mutation
Evidence for Evolution
Slower Rabbit
Scientists have found that some stretches of shared
DNA mutate at regular, predictable rates.
Scientists use this “molecular clock” to estimate at
what time in the past living species diverged from
common ancestors Faster Rabbit
Natural Selection
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