Download 15.1 * The Puzzle of Life*s Diversity

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Interest Grabber
Section 15-1
A Trip Around the World
While on his voyage around the world aboard the H.M.S. Beagle, Charles
Darwin spent about one month observing life on the Galápagos Islands.
There, he encountered some unique animals, such as finches and
tortoises.
1. On a sheet of paper, list five animals that you have encountered in
the past two days.
2. How do these animals differ from the finches and tortoises of the
Galápagos Islands? (Examine Figures 15–3 and 15–4 in your
textbook.)
3. Propose a hypothesis to account for the differences between the
animals that you observed and the finches and tortoises of the
Galápagos Islands.
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* Charles Darwin contributed more to our
understanding of evolution then anyone
* In 1831, he set sail from England to go around
the world
* Darwin came up with a revolutionary
hypothesis of how the way of life changed over
time
* His ideas have become the Theory of Evolution
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* Darwin was fascinated on how wherever he
traveled animals seemed suited for the
environment they lived in
* He collected fossils and saw how creatures of
the past resembled those still living
* The Galapagos Islands is where he was most
fascinated
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Pinta
Pinta Island
Tower
Marchena
Intermediate shell
Fernandina
James
Santa Cruz
Isabela
Santa Fe
Hood Island
Floreana
Isabela Island
Dome-shaped shell
Hood
Saddle-backed shell
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Evolution—change in organisms over time.
(Today, defined as a genetic change in a species over
time).
The expression “evolutionary theory” refers to two
different sets of ideas:
1. The idea that all organisms are descended from a
single ancestor (descent with modification).
2. Ideas of how organisms have changed over time.
(While scientists still debate #2 there is agreement
about #1. Debate about #2 centers around relative
contributions of different mechanisms).
Theory—explains current observations. This explanation
may serve as a basis for generating new predictions.
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Observations/Predictions:
1.
Organisms are organized into groups of similar species that are
part of larger groups and so on, with all life sharing one common
characteristic (RNA is found in all living things).
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2.
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Evidence for relationships between different organisms may be
morphological, embryonic, physiological, biochemical, etc.
The fossil record reveals a general progression from smaller,
simpler forms of life through larger, more complex forms over
long periods of time.
Evolution (descent with modification) explains these
observations and predicts that new organisms/fossils will fit
these same patterns.