Download Natural Selection and the Evidence of Evolution

Natural Selection and the
Evidence of Evolution
Section 15.1
1. Offset your 3 papers and make a
foldable.
2. Title the top flap the title above
3. Title the Other flaps:
1. What is evolution?
2. Darwin-Travels and
Influence
3. Natural Selection
4. Evidences—Adaptations,
Fossil
5. Evidences—Anatomical,
Embyological, Biochemical
Flap 1--What is evolution?
The change in populations over time.
Flap 2--Who is Charles Darwin?
• English scientist/naturalist
whose ideas provide
foundation for the theory of
evolution by natural selection
• Sailed on HMS Beagle for 5
years studying and collecting
biological and fossil
specimens
Major Ports of Call…
• Galapagos Islands
– Location: Near equator, 1000km off west
coast of S. America
– What he studied: many species of animals
and plants unique to the island, but are similar
elsewhere
– Major findings: Observations led to his
consideration that species change over time
Thomas Malthus’ Influence on
Darwin
• Proposed idea that human populations
grow faster than Earth’s food supply
Darwin’s book…
• 1859, The Origin of
Species
• Detailed account on
his ideas and
theories that
support evolution
Flap 3—Natural Selection
• Realized organisms struggle to compete in
changing environments. Many types of
competition exist:
– Food and space
– Escaping predators
– Location of shelter
Insights into why only
certain individuals survive…
• Traits vary among populations; these traits
are inherited
• Breeding with others that had desirable
traits produced offspring with these traits
Darwin’s Hypothesis…
• Artificial Selection- breeding organism with
specific traits in order to produce offspring
with identical traits
• There is force in nature that works like
artificial selection
What is natural selection?
• Mechanism of change in populations over
time
Flap 4-What are adaptations?
• Variation that aids an organisms chances
of survival in its environment
• Develop in a species over many
generations
Structural Adaptations Examples
• Teeth and Claws
– Protect against predators
• Mimicry
– Enables one species to resemble another
• Camouflage
– Enables species to blend with surroundings
Physiological Adaptation
• What are they?
– Changes in organism’s
metabolic processes
• Example:
– After years of exposure
to specific pesticides,
insects and weeds
have become resistant
Fossil Evidence
• Indirect source
• Provide record of early
life based upon rock
layers and location of
fossils within them.
• As record becomes more
complete, the sequence
of evolution is clearer
Example: Archeoptryx
earliest, most primitive bird ~145 mya
Flap 5-Anatomical Evidence
Homologous- common evolutionary origin, features have similar structure
but have different functions. Ex-bat wing and human hand
Anatomical Evidence
• Analogous- no common ancestor, but
similar in function. Organisms like the
shark and dolphin evolved sleek bodies
because they live in similar environments,
not because they are related.
Anatomical Evidence
• Vestigial- body structure in present day
organism that no longer serves original
purpose
Embryological Evidence
The more
similar the
embryos
through out
development
the closer the
evolutionary
relationship.
Biochemical Evidence
• Great table on page 403!
• All organisms share DNA, ATP and many
enzymes among their biochemical
molecules . The more changes the more
time that has passed since they shared a
common ancestor.