Transcript Galapagos Islands

Chapter 15 Part 1
Pg. 91
Evolution Introduction
Definitions to Know
• Scientific Theory = a well-supported,
testable explanation of phenomena
that have occurred in the natural world.
• Evolution = change over time, the
process by which modern organisms
descended from ancient organisms
• Is Evolution Fact or Fiction?
– Scientists believe it’s Fact.
• Proof?
–Fossils
–Speciation
–Geological evidence
–DNA evidence
Charles Darwin (1809-1882)
• British naturalist famous for his
theories of evolution and natural
selection.
• Like several scientists before him,
Darwin believed all the life on earth
evolved (developed gradually) over
millions of years from a few common
ancestors.
• In 1831, Darwin took a trip around the
world on the ship, the M.S. Beagle,
where he collected evidence that led
him to propose his famous
Theory of Evolution.
Charles Darwin
Fossils
• Darwin didn’t just observe and collect living
animals, he also collected fossils.
• Fossils = preserved remains of ancient
organisms
• This led to questions like….
– “Where did all these organisms go?” “Why
aren’t they still here?” “Why do they
resemble organisms we have living today?”
Glyptodon = dead
Armadillo= alive
The Galapagos Islands
• The most important, influential stop on
Darwin’s trip was the Galapagos
Islands
• 1000 km west of S. America, a cluster
of islands isolated by miles of sea
• The islands had different climates, and
Box 7
therefore, had different varieties of
animals and plants
Animals Darwin studied:
1.
Giant Tortoises
3. Finches
2. Iguanas
Galapagos Turtles
Each turtle lives on a
certain island, and their
shells are different, islanddependent!
Pinta
Tower
Marchena
Pinta Island
Intermediate shell Fernandina
Hood Island
James
Saddle-backed shell
Santa Cruz
Isabela
Santa Fe
Floreana
Isabela Island
Dome-shaped shell
Hood
The shape of each turtle’s shell is
different and the different shapes
depend on the turtle’s habitat.
Darwin’s Finches
• Darwin also collected finches, birds, matching
their beak and body shapes with different
islands- just like the tortoises.
• Adaptive Radiation – the evolutionary
process through which a single lineage gives
rise to species occupying diverse
environmental niches.
Tree Finch
Ground finch
In other words, if you get
separated from your own
species, you evolve or change
in response to your
environment.
Darwin’s Finches
Leaves
Seeds and Fruit
Seeds
Insects
Grubs
Tool using
What took him so long? 25 years later….
• In 1858, Alfred Wallace sent Darwin an essay
with the same ideas about evolution!
• They presented their work together at a
conference, but….
• This pushed Darwin to publish
his work, before Wallace
• The Origin of the Species
– Proposed a mechanism for
evolution, called Natural
Selection
– Presented evidence that evolution has
been happening for millions of years