EVOLUTION
Darwin’s Theory
Slides 1 – 24
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Consider This…
• “Individual organisms live, reproduce and die.
Individuals, however, do not evolve;
populations do. Evolution is the change in gene
frequency that occurs in a population over
time.”
• Audesirk, T. & Audesirk G. Biology – Life on Earth. 4th edition. © 1996
• Population: all the individual members of a particular
species living in a given area.
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Biological evolution…
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Misconceptions
Is NOT “just a theory.”
In science, theory ≠hypothesis
Has NO political agenda.
Does NOT have a direction.
Has NO ultimate goal.
Was NOT discovered by Darwin.
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Pre-Darwinian Evolutionary Ideas
• Jean Baptiste de Lamarck
(1744 – 1829) French Biologist
• First complete explanation of
evolution (1809)
• Inheritance via acquired
characteristics –
• Claim: Organisms transform their
appearance to produce evolution.
Giraffe necks =
evidence?
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Charles Darwin
• 1831
• At only 22 years old, this
British nature lover went
for a 5-year cruise onboard
her majesty’s Beagle ship.
• He sailed around the world
to look at stuff. The most
famous stop being the
Galapagos islands off the
coast of South America.
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Biodiversity
VARIATION!
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VARIATION / Biodiversity
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Beaks differ
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Abundant babies!!!!!
OVERPRODUCTION!
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Blue feet?
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ADAPTATIONS ?
Adaptation
• Book definition:
A trait that helps
an organism
survive and
reproduce.
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Darwin’s Notes
• Observation 1: Overproduction – Organisms
make more offspring than can survive.
• Observation 2: Resources are Limited.
• Conclusion 1: Competition for survival and
reproduction among species.
• Observation 3: Individuals Differ from one
another within a species’ population.
• Conclusion 2: Fitness – the most well-adapted
individuals from one generation will usually
leave the most offspring.
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Twenty Years Later
• Darwin finally publishes his book On the Origin of Species,
sharing his theory of Evolution by Natural Selection (1859).
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Terms
Evolution
change in a population’s
genes from one
generation to the next.
• a.k.a. change over time.
Natural Selection
Nature selects who
stays!!
• This process drives
evolution.
• Adaptation- A trait that helps an organism to survive &
reproduce (born with it).
• Adaptations are favorable variations.
• Variation- Differences between individuals of the same
species.
• Examples: color, shape, size, behavior, chemistry.
• Variations come from:
• Mutations.
• Meiosis Cross Over (challenge topic)
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Populations will have a pool of genes.
• A gene pool is all
the genes that
occur in a
population.
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Five Fingers of MicroEvolution
Mutations workshop…
THE FAT CAT ATE THE RAT.
DNA
Replication
THE FAT CAT ATE THE RAT.
THE FAT CAT ATE THE RAT.
Mutation
THE FAT CAR ATE THE RAT.
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Common Ancestry
Australopithecus (Genus)
4 mya
Genus of Hominids (Family).
“Lucy” 3.2 mya (Ethiopia)
Extinct
Homo habilis
2.33 – 1.44
mya
Short, long arms. Primitive
stone tools. Extinct.
Homo erectus
1.9 mya –
143,000 years
ago
“Upright man”
Homo neanderthalensis
600,000 –
Homo sapeins neanderthalensis (?) 350,000 years
ago
Homo sapiens
Homo sapien sapiens
Interbreeding?
Climate change?
200,000 years
ago
“intelligent”
Extant!
Modern humans. Extant.
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MUST KNOW Evolution Vocab
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Adaptation
Branching tree
Competition
Common ancestor
Darwin, Charles
Evolution
Extinct
Fossil
Fossil Record
Gene pool
Gradualism
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Half-life
Homologous structures
Mutation
Natural selection
Overproduction
Punctuated equilibria
Radioactive element
Relative dating
Scientific theory
Species
Variation
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More Evolution Vocab
SHOULD KNOW
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Analogous structures
Artificial selection
Cast
Coevolution
Mold
Perpetual change
Petrified fossil
Lamarck
Vestigial structures
CHALLENGE
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Altruism
Convergent evolution
Disruptive selection
Founder effect
Genetic drift
Sexual selection
Stabilizing selection
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Name 3 Misconceptions
about EVOLUTION:
1)
2)
3)
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Turn & Talk to Complete this frame:
microEVOLUTION
MACROEVOLUTION
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What did Darwin OBSERVE?
#1)
#2)
#3)
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What did Darwin CONCLUDE?
#1)
#2)
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Evolution,
part II
Oh yea, PROVE IT!
Proof
Fossils
Comparative Anatomy
Comparative Embryology
Vestigial Structures
Comparative Biochemistry
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Evidence
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Thermodynamics
Evolution
Gravity
• Recall that a scientific theories…
• Are well supported.
• By appropriate & sufficient evidence.
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Explain many observations
Are testable.
Are widely accepted.
Incorporate facts, laws, inferences and tested hypotheses.
Are NOT “just a theory.”
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Pangaea 200 mya
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Evidence for Evolution
• Biogeography
• Ex: Galapagos species
• Fossils
• Ex: Horses
• Homologies
• Ex: Anatomy
• DNA & Proteins
• Ex: Human FGF2 Gene
• Mathematical Models
• Population simulation
• Artificial Selection
• Ex: Antibiotic resistance
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Fossil Evidence
• Fossils are the remains of past life
dug up from the earth’s crust.
• Fossil formation is rare.
• Most fossils form in sedimentary
rock.
• Fossils are the historical documents
of biology.
• Because the Earth’s crust
is layered over time,
younger fossils are found
closer to the top.
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Examples: bone, teeth, casts, impressions.
Why are primate fossils rare?
1) Most primates did not live in habitats that
readily preserved fossils, such as swamps and
shallow lagoons.
2) Until recently, primates were fairly small.
3) Ancestral primates may have had small
populations, thus providing less material for
fossilization in the first place.
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FYI - Primate evolution has been linked to grasping
hands, binocular vision and a LARGE brain.
Fossil Record Evidence
• If you piece together all the millions of fossils
that scientists have dug up and sequence them
by time (age), you have the Fossil Record.
• How do you know a fossils age?
• Relative dating
• Top vs. Bottom layers.
• Radioactive dating
• Unstable element decay of nearby rocks.
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Embryology Evidence
• Looking at the early development of one
organism and comparing it to another allows
scientists to make inferences about their
evolutionary relationship.
• Embryo: Not yet born, developing multicellular
organism.
• Inference: using clues to make a conclusion.
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Homologous Structures Evidence
• Definition: similar structures that related
species have inherited from a common
ancestor.
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Biochemical evidence
• Results from DNA
& protein analysis
further support
the theory of
evolution by
natural selection.
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Summary
• Evolution by means of natural selection explains
the history of life on earth. This claim is
supported by abundant evidence.
• Key Concepts are:
• Species share common ancestors.
• Descent with modification: (perpetual change)
• Nature chooses which species stay (extant) and which
go (extinct).
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Class Discussion
• Which is more likely to form a fossil
• Jellyfish or crab?
• Why are there gaps in the fossil record?
• How do you interpret an evolutionary tree diagram?
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7) High School Challenge
• Describe the role that geographic isolation can play in
speciation.
• Speciation = new species formation.
• Research:
• Allopatric speciation
• Vicariant vs. founder effect.
• Sympatric speciation
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Darwin’s Work
• 1. Variation: There is Variation in Every
Population.
2. Competition: Organisms Compete for limited
resources.
3. Offspring: Organisms produce more Offspring
than can survive.
4. Genetics: Organisms pass Genetic traits on to
their offspring.
5. Natural Selection: Those organisms with the
Most Beneficial Traits
are more likely to Survive and Reproduce.
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The History of Evolutionary
Thought
• Plato (Greek philosopher 427-347 B.C.E.)• Aristotle (Plato’s student 384-322 BCE)-
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High School Challenge
• Lamarck v. Darwin
• Who is Jean-Baptiste Lamarck & how did his take on evolution
differ from Darwin’s?
• Hardy-Weinberg equation
• p2+2pq+q2=1; p+q=1
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