Download Evolution Unit

8-3 NOTES:
DARWIN VS. LAMARCK
BEFORE DARWIN
• People believed earth was only
thousands of years old and
organisms did not change.
• However, this did not explain the
fossil record that showed very
different organisms living in areas in
the past.
EVOLUTION
oDevelopment of new types of organisms from
preexisting organisms over time.
oTwo scientists had theories as to how organisms
changed over time.
oDarwin and Lamarck
Lamarck’s Ideas
oProposed the idea of acquired traits to explain the
changes.
oChanges in environment caused an organism
behavior to change creating a new physical trait.
Lamarck’s ideas
oTraits used most often would be
enhanced and passed to offspring
oTraits that were not used would
diminish and disappear from offspring
Using what we know about genetics, can we
disprove the theory of inheritance of acquired traits?
Darwin’s Ideas
oArgued that descent with modification
occurs
oProposed that Natural selection is the
mechanism for evolution.
oDarwin’s idea that small changes accumulate
over generations.
Darwin’s Ideas
oThe variation of trait that is beneficial for survival
became more common.
oEx. Giraffes with slightly longer necks survived and
reproduced
VOYAGE ON THE H.M.S BEAGLE
oDarwin went on a five year voyage where he
collected many artifacts
VOYAGE ON THE H.M.S BEAGLE
oWent to Galapagos Islands and noticed variations of animals
were well suited to animals environment
ovariation- differences in physical traits
Darwin’s Finches
o13 finch species
that evidence
suggests descended
from one original
species from
Ecuador
Darwin’s Finches
oEach island had different climates and food
sources
oEach finch species beak was best suited for
eating the available food source
VOYAGE ON THE H.M.S BEAGLE
oHe said some how they had to adapt to their
surrounding!
VOYAGE ON THE H.M.S BEAGLE
oDarwin observed fossil and geologic evidence
supporting an ancient Earth.
o Suggested that modern organisms have relationship
to fossil forms.
VOYAGE ON THE H.M.S BEAGLE
Darwin said, like
the Earth,
organisms must
some how
gradually change
over time
DARWIN VIDEO
CLASS WORK
Darwin and Lamarck 4-squares
Darwin vs. Lamarck