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Tree of Life
What mechanism
gave rise to the
diversity of life
that we see
today?
Theory of Evolution by
means of Natural Selection
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Charles Darwin
1809- 1882 • While on the voyage of the HMS Beagle in
the 1830s as ship’s naturalist to Captain
Fitzroy- Mapping Expedition
• Charles Darwin observed similarities
between living and fossil organisms and the
diversity of life on the Galápagos Islands
North
America
Great
Britain
Europe
Asia
ATLANTIC
OCEAN
PACIFIC
OCEAN
Africa
PACIFIC
OCEAN
Equator
The
Galápagos
Islands
PACIFIC
OCEAN
Pinta
South
America
Genovesa
Australia
Equator
Santiago
Pinzón
Fernandina
0
0
Cape of
Good Hope
Tasmania
Isabela
Figure 13.1B
Daphne
Islands
Andes
Marchena
Santa Santa
Cruz Fe
Cape Horn
San
Cristobal
40 km
Florenza
40 miles
Española
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Tierra del Fuego
New
Zealand
DARWIN’S THEORY OF EVOLUTION
Voyage of the Beagle helped
Darwin frame his theory of
evolution
On his visit to the Galápagos
Islands:
Charles Darwin observed many
unique organisms- marine iguanas,
tortoises, and the finches.
Each of the above was similar to a
organism found on the mainland and
each sub group on the different
islands seemed similar to each
other.
Figure 13.1A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
13.2 Darwin proposed
natural selection as the
mechanism of evolution
1.Produce more
offspring than the
environment can
support
2. Individuals vary in
many characteristics
that can be inherited
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Darwin reasoned that natural selection
– Results in favored certain traits being
represented more and more in
subsequent generations and unfavored
ones less and less. Differential selection
or differential reproduction
Survival of the
fittest
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Only the those with
the best combinations
of traits survive to
reproduce and pass
their genes on-
Clown, Fool, or Simply Well Adapted?
• The blue-footed booby
– Is a type of bird living in the Galápagos
Islands
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• This type of bird possesses many specialized
characteristics, called evolutionary adaptations
– Which are inherited traits that enhance its
ability to survive and reproduce in its
particular environment
Birds need to
balance the
adaptations of
living on land
and being
successful
aquatic
predators
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
• Darwin found convincing evidence for his ideas
in the results of artificial selection
–
The selective breeding of domesticated
plants and animals
Hundreds to thousands
of years of breeding
(artificial selection)
Ancestral dog (wolf)
Figure 13.2A
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Figure 13.2B
• Darwin proposed that living species
– Are descended from earlier life forms
and that natural selection is the
mechanism of evolution
African wild dog
Coyote
Wolf
Thousands to
millions of years
of natural selection
Figure 13.2C
Ancestral canine
Copyright © 2005 Pearson Education, Inc. Publishing as Benjamin Cummings
Fox
Jackal