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10.1 - 10.2 Presentation

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PRINCIPLES
OF
EVOLUTION
Chapter 10
Contents
■ 10.1 Early ideas about evolution
■ 10.2 Darwin’s observations
■ 10.3 Theory of Natural Selection
■ 10.4 Evidence of Evolution
■ 10.5 Evolutionary Biology Today
Chapter 10
Section 1
EARLY IDEAS
ABOUT
EVOLUTION
There were theories of biological and
geological change before Darwin
Main Ideas
Vocabulary
■ Early Scientists proposed ideas
about Evolution
■ Evolution
■ Theories of geological change set
the stage for Darwin’s theory
■ Species
■ Fossil
■ Catastrophism
■ Gradualism
■ Uniformitarianism
EARLY SCIENTISTS PROPOSED
IDEAS ABOUT EVOLUTION
EVOLUTION
the process of biological change by
which descendants come to differ
from their ancestors
Early Naturalists – Carolus Linnaeus
■ Proposed a new system of organization for
plants and animals
■ System was organized on the similarities of
organisms
■ This system is still in use today and reflects
evolutionary relationships
1735
■ SPECIES = a group of organisms so
similar to one another that they can
reproduce and have fertile offspring.
Early Naturalists – Georges Buffon
1749
■ Discussed important ideas about:
– Relationships among organisms
– Sources of biological variation
– The possibility of evolution
■ Proposed that species shared ancestors
instead of arising separately
■ Rejected the idea popular at the time that
the Earth was only 6000 years old
■ He suggested Earth was much older
Early Naturalists – Erasmus Darwin
■ Charles Darwin’s grandfather
■ Considered how organisms could evolve
through mechanisms such as competition
■ Proposed that all living things were
descended from a common ancestor
1795
■ Thought that more complex life arose from
less complex forms
Early Naturalists – Jean-Baptiste Lamarck
■ Proposed that all organisms evolved
toward complexity
■ Thought the environment caused
organisms’ behavior to change
1809
■ Their organs would become larger or
smaller due to use or disuse
■ Inheritance of acquired characteristics
■ Famous example of giraffes
Lamarck’s Giraffes – Inheritance of acquired characteristics
■ giraffe necks become
longer as the animals
try to stretch their
necks to reach food.
■ The longer necks
acquired in this way
would then be passed
on to their offspring
■ We now know that this
idea is WRONG!
However, Darwin was influenced by Lamarck’s ideas that:
• physical characteristics could be inherited
• Changes in species were influenced by the environment
THEORIES OF GEOLOGICAL
CHANGE SET THE STAGE FOR
DARWIN’S THEORY
Catastrophism –
Georges Cuvier
Early 1800s
■ Interested in fossils: traces of
organisms that existed in the past
■ Did not think that species could
change since God created them
■ Appearance of new species
resulted from catastrophic events
such as floods and volcanoes
Gradualism
Late 1700s
James Hutton
■ Proposed that changes in
landforms resulted from
slow changes over a long
period of time
■ Processes like a river cutting
through rock to create a
canyon take place slowly
and gradually
■ The term gradualism is often
used now to mean the
gradual development of a
species through evolution.
Uniformitarianism
Charles Lyell
1830s
■ The geological processes that shape the Earth
are uniform through time.
■ ”The present is the key to the past”
■ The small, slow processes occurring now were
the same in the past
■ This idea replaced catastrophism as the
favored theory of geological change
■ Lyell’s ideas greatly influenced Charles Darwin
■ Uniformitarianism is accepted in modern
geology
Chapter 10
Section 2
DARWIN’S
OBSERVATIONS
Darwin’s voyage provide insights into
evolution
Main Ideas
Vocabulary
■ Darwin observed
differences among island
species
■ Variation
■ Darwin observed fossil
and geological evidence
supporting an ancient
Earth
■ Adaptation
DARWIN OBSERVED DIFFERENCES
AMONG ISLAND SPECIES
Darwin’s Voyage
■ Darwin set sail in 1831 on the ship
HMS Beagle
■ 5-year journey
■ Went to South America, Africa, and
the South Pacific Islands
■ During the voyage he read Lyell’s
book Principles of Geology
■ Darwin observed living things,
geological formations, and fossils
across the world
■ He saw a lot of VARIATION in
organisms
Variation
■ The difference in the physical
traits of an individual from those
of other individuals
■ Interspecies Variation: variation
among members of different
species
■ Intraspecies Variation: variation
among members of the same
species
Darwin’s
Observations in
South America
■ Darwin saw that the
species on one island
looked different from the
species on other islands
■ Many species on islands
looked different from
those on the mainland
■ His observations of
organism in Galapagos
Islands were key to the
development of his theory
Darwin’s Observations:
Galapagos Tortoises
■ Some variations seem wellsuited to the environments and
diets of the animals
■ Saddle-backed tortoises have a
high shell edge allowing them to
stretch their long necks to reach
the tall plants on their island
■ Domed tortoises have short
necks and legs. The islands they
live on have low vegetation
Darwin’s
Observations:
Finches
■ Finches with strong
thick beaks lived in
areas with large
hard-shell nuts
■ Finches with
delicate pointy
beaks lived on
islands where fruits
and insects were
available.
Adaptations
■ From his
observations
Darwin developed
the idea of an
ADAPTATION
■ Adaptation = a
feature that
allows an
organism to
better survive in
its environment
DARWIN OBSERVED FOSSIL AND GEOLOGICAL
EVIDENCE SUPPORTING AN ANCIENT EARTH
Darwin found fossil
evidence of huge
animals
■ Glyptodon – giant
armadillo
■ Looked like modern living
species
■ Suggested that modern
animals might be related
to fossil forms
■ Suggests Earth must be
very old for there to be
time for this change
Darwin found fossil
shells on the tops of
high mountains
■ He experienced an earthquake
that lifted a section of
underwater rock eight feet
above the ocean overnight
■ He saw that this supported
Lyell’s ideas about small
processes that can add up to
big change over time
■ An ancient Earth and slow
gradual change could also
explain how species evolved
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