Darwin’s Theory of Evolution
Objectives
1. Summarize ideas from
Darwin’s time that
influenced his work.
2. Identify some key
observations from
Darwin’s voyage that
led to his theory.
3. Describe the two main
points of Darwin’s
theory.
Vocabulary
Evolution
Adaptation
Descent w/ Modification
Natural selection
Evolution:
Process by which modern
organisms have descended
from ancient organisms
(change over time)
Natural Selection = Mechanism for
Evolution
Based on the following principles:
• Struggle for Existence: Organisms generally have more
offspring than resources can support
• Natural Variation: W/in species there will be VARIATIONS in
traits (due to genetic mutation & recombination)
• Adaptation: Some variations provide an advantage that increases
chances of survival.
• Survival of the Fittest: Those with the adaptations are more
likely to survive and reproduce
• Descent with Modification: Genes for beneficial adaptations
are passed on & trait becomes more common in each new
generation.
Charles Darwin (1809 -1882)
Proposed THEORY OF EVOLUTION.
1. “Descent with Modification”
 Change in species over time.
 Modern organisms descend from ancient.
 Adaptations are acquired in response to changes
in habitat

Adaptation: Inherited trait that improves ability
to survive & repro.
2. NATURAL SELECTION = mechanism
Well suited individ. SURVIVE & REPRO.
More offspring (pass genes on)
Old Ideas
Before Darwin
 Species are fixed or permanent
 Earth was less than 10,000 years old (and unchanging)
Darwin’s Influences




Lyell: Study of fossils, rock record, and geologic
processes … Earth is much older than 10,000 and
Earth CHANGES.
Farmers: Selective breeding can change species.
Malthus: Economist (Famine & disease result when
population are bigger than resources…Competition for
resources, “survival of the fittest” idea)
Lamarck (1800): Inheritance of Acquired
Characteristics (Organisms can adapt!)
Lamarck’s Theory of Evolution
Inheritance of Acquired
Characteristics
Based on 3 Ideas
1. Desire (will) to change
2. Use and Disuse
3. Passing on acquired traits


Introduces idea that populations
CAN EVOLVE or CHANGE
(correct)
Knew NOTHING about
GENES/GENETICS.
Sorry Lamarck: Organisms can
only pass on traits encoded in
DNA (not traits acquired by
behavior)
Darwin’s Observations
Voyage on the BEAGLE
Galapagos:
Unique organisms - similar to, but
different from plants on nearest
mainland.
Each island had some unique
species.
Mainland species had changed
after they colonized the islands and
adapted to new environments.
Wrote: On Origin of Species (w/ Wallace), 1858
Unique Species of Galapagos
Each island has
unique species
that show a
relationship to
one another and
mainland.
Peppered Moths: Natural Selection
in Action
Which one is best “fit” for the environment?
What happened?
Relative frequency of
alleles for color
changed in the gene
pool for the
population.
Why?
Change in selective
pressure
http://www.aurumscience.com/biology/11_evolution/great_transformations.html
Evolution
Is it incorrect to state that humans evolved from
monkeys? Defend your answer with reasons and
evidence.
Evolution
While this bird-shark is cool, why is it unlikely to evolve
from either birds or sharks? Defend your answer with
reasons and evidence.
Self Quiz
1. You hear someone remark that evolution
says we come from monkeys. Educate
them with your response.
2. Discuss 1 influence (person) on the
development of Darwin’s theory. Explain
HOW this influence relates to Darwin’s
EVOLUTION.
Self Quiz
3. What did Lamarck get right? What did
he get wrong?
4. 2 Sentence Summary: What is evolution
and how does it work?
Links
Superbugs & Antibiotic Resistance: http://www.huffingtonpost.com/2013/03/06/superbugla_n_2820603.html
Superbug & Antibiotic Resistance: http://fox59.com/2013/03/06/cdc-warns-hospital-patients-about-drugresistant-superbug/#axzz2QFi4CFgT
PBS’s Evolution: Great Transformations Episode 2
http://www.youtube.com/watch?v=CXgQOj3dAM&playnext=1&list=PL025876CC77CDD9AE&feature=resu
lts_main
PBS’s Evolution: Extinction Episode 3
http://www.youtube.com/watch?v=d0p9NecLfZs&list=PLFA1
0790C7F78A11F