Transcript 15.1 Puzzle of Life`s Diversity

Unit 5
Central Ideas of Evolution:
◦ Life has a history
◦ It has changed over time
◦ And different
species share common
ancestors.
Science tries to explain the past in terms of
events/processes we can observe, measure
and replicate today.
The variety of living things is called
biological diversity.
He contributed most to the
understanding of evolution
 Born in England
 Naturalist on the crew of
H.M.S. Beagle (1831)
 During travels, made
numerous observations
and collected evidence to
propose how life changes
over time.
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Collected plant and animal
specimens at every stop.
Well educated and curious
Strong interest in natural
history
Noted more diversity than
his native country
Collected 68 different beetle
species in one Brazilian forest.
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Darwin also found and
collected fossils
He questioned:
 Why had so many species
disappeared?
 How were they related
to living species?
Actual Remains
- Real tissue or portion of
once living thing
Casts
- Imprint in rock
- Color of imprint
same as surrounding
Mineral Replacement
- Organic changed to
mineral rock
1000 km west of
South America
Influenced Darwin
the most
Although islands close,
they had very different
climates.
Most fascinated by land tortoises and
marine iguanas
Pinta
Pinta Island
Intermediate
shell
Fernandin
a
Isabela
Tower
Marchena
James
Santa
Cruz
Santa Fe
Floreana
Isabela Island
Dome-shaped shell
Hood
Hood Island
Saddle-backed
shell
Although Darwin
observed plants and
animals varied
noticeably among
different islands, could
it be possible they had
evolved from an
original South American
species?
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Darwin also knew that individuals differ from
all the other members of its species
Sometimes differences easy to observe
Sometimes differences are subtle
Variation necessary for evolution by natural
selection
Do Lima Beans Show Variation?
Procedure:
1. Count out 10 lima beans and measure the
length of each in millimeters. Record your
results in a data table.
2. Combine your data with the data of two other
classmates. Place all the data on one graph.
Plot the length on the x-axis and the number
of beans of each length on the y-axis.
Analyze your data and Make predictions.