Darwin’s Theory of Evolution
The Puzzle of Life’s Diversity
Chapter 15-1
Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006
What scientific explanation can account for the
diversity of life?
ANSWER:
EVOLUTIONARY THEORYA collection of Scientific Facts, observations and
hypotheses
WRITE A DEFINITION:
EVOLUTION:
change over time; the process by which modern
organisms have descended from ancient organisms
THEORY:
a well-supported testable concept that is supported by
evidence
http://harrier.users.netlink.co.uk/Darwin_sm.jpg
The person who contributed the
most to our understanding of
evolution was Charles Darwin
In 1831, he joined the crew of the Beagle as a
naturalist for a 5 year voyage around the world.
Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006
DARWIN WONDERED?
Why do Argentina and Australia have different
Animals even though they have similar
grassland?
Why are there no rabbits in Australia and
no kangaroos in England?
Why have so many species
disappeared?
How are these extinct species
related to living species?
http://www.rc.umd.edu/praxis/mitchell/images/dinosaur1.gif
• Fossil record showed 2 types of organisms
– Ones that were similar to animals and plants alive
at the time
– Ones that were different to animals an plants
alive at the time
• Why had these
species disappeared?
Darwin's greatest influence
Charles Darwin spent one month observing life on
the Galapagos Islands.
There, he encountered some unique animals, such
as finches and tortoises.
http://www.darwinadventure.com/pictures/galapagos_giantortoise.jpg
http://mikebaird.com/ecuador/images/galapagos_off_ecuador_ng_map.jpg
The Galάpagos Islands are close together but
have very different climates.
• hot and dry, with little vegetation
• more rainfall and were rich in vegetation
Each island had
its own unique
Assortment of
plant and animal
species.
Biology by Miller and Levine; Prentice Hall Publishing©2006
Giant Tortoises of the Galápagos Islands
Section 15-1
and on Pinta Island, tortoise necks
were somewhere in between
Pinta
Pinta Island
Tower
Marchena
Intermediate shell
Fernandina
James
Santa Cruz
Isabela
Santa Fe
Hood Island
Floreana
Isabela Island
Hood
Saddle-backed shell
On the desert-like Hood Island,
tortoises had long necks…
Dome-shaped shell
…while
Go to on the lush rainforest of Isabela Island,
Section:tortoises had short necks…
After his voyage, Darwin spent a great deal
of time thinking about his findings.
Biology by Miller and Levine; Prentice Hall Publishing©2006
Darwin’s Theory of Evolution
Ideas that Shaped Darwin’s Thinking
Chapter 15-2
Image from: Biology by Miller and Levine; Prentice Hall Publishing©2006
Ideas that shaped Darwin’s thinking:
James Hutton (1795)the EARTH was shaped by geological
forces occurring over very
long periods of time, and the Earth is
millions of years old.
Ideas that shaped Darwin’s thinking:
Charles Lyell (1830)the geological processes still occurring now
have shaped Earth’s features over long periods
of time
http://www.biologydaily.com/biology/Sir_Charles_Lyell
Ideas that shaped Darwin’s thinking:
Theory of Pangaea
Ideas that shaped Darwin’s thinking:
Continental drift
divergent
convergent
Transform
Ideas that shaped Darwin’s thinking:
Thomas Malthus (1798)• If the human population continued to grow
unchecked, there would be insufficient living
space and food.
http://www.educa.rcanaria.es/fundoro/00.corsi.htm
Ideas that shaped Darwin’s thinking:
Jean-Baptiste Lamarck (1830)• one of first scientists to recognize
living things changed over time and that all
species were descended from other species.
Lamarck's Hypothesis:
1. Tendency towards perfection
2. Use and disuse
3. Inheritance of acquired traits
http://www.geocities.com/arnold_schwarzenegger_pictures/
What’s wrong with Lamarck’s hypothesis?
Lamarck didn’t know about
genes and how traits are
inherited.
If you lifted weights your
whole young adult life, and
then you had children, would
your kids be more muscular?
NO! acquired traits can not be passed on to their
offspring.
The male fiddler crab uses its
front claw to attract mates and fight
off predators.
Through repeated use, the front claw
becomes larger.
The fiddler passes on this acquired
characteristic to its offspring
Individuals DO NOT evolve!!!!
Acquired traits cannot be
inherited
What’s right with Lamarck’s hypothesis?
Lamarck was first to
develop a scientific
hypothesis about
evolution
and recognize that
organisms are
Adapted to their environment
What does drive evolution?
•Inherited adaption's
that accumulate in a
population over many
generations= Evolution
•Living things must
compete for food,
shelter, space and
mates
http://www.wasatchcomputers.net/gallery/elk_fight.jpg
competition