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The Theory of Evolution by Natural
Selection
Charles Darwin
Before Darwin:
Strong religious power
1800s Lamarck (scientists) believed that
organisms change based on needs
What was Thought..
Later Proved Wrong
Topic 1: Darwin’s Mechanism for
Evolution
• 1859 Charles Darwin developed theory of evolution
– Decades of science observations & experiments
– Struggled in life: parents, school, religion
– Interest in natural science conflicted his parents values
• 1831 HMS Beagle voyage to S. America (5 years)
– Found evidence that species change over time
• Fossils
• Influenced by Malthus (increase in human population Vs food)
• Charles Lyell (earth geology is changing)
The HMS
Beagle
• Galapagos Islands
(off coast of Ecuador)
• Species there were similar to
mainland but not the same
– “descent with modifications”
– OR evolution!!
Studied many organisms
Turtles, Iguanas, Finches most
popular
Evolution by Natural
Selection
• Darwin’s association with Malthus:
–“Natural Selection”
–Favorable traits are selected for by
NATURE NOT THE ANIMAL!!
Evolution by Natural
Selection
• This “selection” or favorable VS unfavorable
CAUSES changing in a population
(EVOLUTION)
– Organisms differ from place to place because their
habitats change from place to place
– Form ADAPTATIONS (selective advantage)
examples
Animal Mimicry!
Open Notes Pop Quiz!
1. Name a scientists that influenced Darwin’s theory
of evolution? What did that scientist do?
2. What was the name of the most famous island
Darwin traveled to during his voyage?
3. The favorable traits are selected by___________
for natural selection.
4. What is an adaptation?
Finished?
Make 4 Post-its about the notes we took today!
Darwin’s Theory of Evolution
• Published in The Origin of Species
– SERIOUSLY controversial (humans evolved from apes)
• 4 Major points to Evolution
4 major points to Theory of Evolution
1. Variation exists within the genes of every
population or species (random mutation)
4 major points to Theory of Evolution
2. In a particular environment, some individuals of a
population or species are better suited to
survive and have offspring
4 major points to Theory of Evolution
3. Over time, the traits that make certain individuals
of a population able to survive and reproduce tend
to spread in that population
4 major points to Theory of Evolution
4. There is overwhelming evidence from fossils and
many other sources that living species evolved from
organisms that are extinct (EVOLUTION)
Tempo of Evolution
• Gradual change over
long periods of time
– Gradualism
• Rapid change
separated by periods
of little or no change
– Punctuated
equilibrium
Anatomy and Development
• Vestigial Structures:
evidence of evolution, not
used today
• Homologous structures:
share common ancestor
because of structure NOT
FUNCTION
Notes Quiz
1. What are the 4 points to Darwin’s Theory of
Evolution? Give an example of each
2. What are the 2 tempos of evolution? Give an
example of each
3. What is the difference between a
homologous trait and a vestigial trait?
Do Now:
• List any examples of evolution found in the following
species
– Tigers
– Whales
– Turkeys
– Insects
– Humans
Examples of Evolution
• NATURE selects the favorable traits!
– 4 Factors that drive natural selection
Topic 2: 4 factors of Natural Selection
1. All populations have genetic variation
4 factors of Natural Selection
2. The environment presents challenges to successful
reproduction
4 factors of Natural Selection
3. Individuals tend to produce more offspring than the
environment can support (COMPETETION)
4 factors of Natural Selection
4. Individuals that are better able to cope with
environmental challenges tend to leave more
offspring than those less suited to their environment
Examples of Evolution
• Antibiotic Resistance in
Bacteria
– Tuberculosis 1980s, new
strains
– Original drugs Isoniazid and
Rifampin don’t work
anymore
Pesticide Resistance in Insects
EID Emerging Infections
Diseases!!
Re-Emerging Infectious
Diseases
Topic 3: Examples of Evolution
• Darwin’s Finches
– 31 specimens
– 9 with similarities
except for beaks
• Determined by
availability of food
supply
-Damp Year
Small narrow
-Dry Year
Big thick
Formation of New Species
• Occurs in stages to best “fit” environment
– Divergence- differences between groups
– Leads to formation of new species (speciation)
• Formation of Sub-species
– Different habitats  different needs difference in species
• Maintaining New Species
– Reproductive barriers
• Timing, geography, physical traits
Review
Write this down
1. What are the reproductive barriers when maintaining a new
species?
1. Geography, timing, physical traits
2. What are the 4 factors of Natural Selection
1. Adapt or die, competition, nature’s challenges, variation
3. Example of a vestigial trait?
1. Whale hip-bone
4. Example of homologous trait?
1. Bat wing, human arm
The Evolution of Man
32.3 (731-738)
Darwin theorized that humans evolved from primates
(prosimians, monkeys, apes) because of certain traits
1. Grasping Hands cling to mothers, branches, food
2. Forward Eyes judge distance, depth perception
First primates evolved ~50 million yrs ago (MYA)
Non-Human Primates
Monkeys & Apes ~36 MYA
– Diurnal (sleep at night, active during day)
• Detect predators & food
• Monkeys
– First primates with opposable thumbs
• Apes
– No tail, larger brains
– DNA of chimpanzee is 95% identical to
human DNA
Human Primates (Hominids)
• Primates that walk upright on 2 legs = hominid species
– 5-7 MYA
– Early hominids walked on all fours…why change?
– “Lucy” is an Australopithecine afarensis
•
•
•
•
3 MYA
Increased brain size
Walked upright
~40lbs and 3.5 ft tall
Homo habilis, erectus, sapien
• Homo habilis = “Handy man” 2MYA
– Tools & speech
• Homo erectus = “Upright man” 1.5MYA
– Evolved in Africa and migrated to Asia
• Homo sapien = “Wise man”
~200,000 yrs
– Only surviving of the hominids
– Modern day human species and genus
VIDEO!!!!!
• https://www.youtube.com/watch?v=ad0ELPLAN
WM&feature=related