Transcript Evolution vs. Intelligent Design

Evolution
Unit Question: To
what extent does
the environment
influence living
things over time
Area of
Interaction:
Environment
Evolution
change
over
time.
Charles Darwin???
Fact, Fiction, Theory & Law:
How are they different?
Fact: something that has
actual existence.
Ex. space exploration is
now a fact
b : an actual observable
occurrence in our time
Fiction:
a: something invented by
the imagination or
feigned; specifically :
an invented story
b: fictitious literature (as
novels or short stories)
c: a work of fiction;
especially : NOVEL
Hypothesis: an
interpretation of a
situation
a: an educated ‘best guess’
Theory: A well supported testable explanation
of phenomena that have occurred in the
natural world.
a: a plausible or scientifically acceptable
general principle
offered to
explain phenomena
<wave theory of
light>
A Hypothesis becomes Theory
when it is supported by a huge
body of evidence after lots of
testing.
Law: very much like a theory, less
complex
a: a statement of provable scientific
knowledge related to a single
measurable phenomenon. ie Law of
Gravity, Law of thermodynamics
b: specific and measurable
PBS 6 Min Vid
Deep thoughts
• So what is evolution?
– Fact or fiction?
– Hypothesis, Theory, or Law?
– Is evolution debatable?
• How do ideas change over time with
new scientific evidence? Give
examples.
Evolution
• Change over time
• In biology it is the process by
which modern organisms have
descended from ancient organisms.
3 million years ago
50 million years
Who is Charles Darwin?
- Proposed theory to explain evolution
- Theory called Natural Selection
Darwin - Early Years
• Terrible student
– Medical school at age 16 (Edinburgh, Scotland,
established 1582!-ancient university)
– Skipped class to collect biological specimens
– Sat in on classes in geology and botany
• Father removed Darwin due to lack of
academic progress
Darwin – Early Years
• Clergymen - University of Cambridge
• Preferred competitive collecting of beetles,
riding, and shooting to studying – but did
graduate.
Beetling was the craze at that time…
Darwin – How it all started
• Darwin was recommended as a naturalist and
much needed gentleman’s companion to
Captain Robert Fitzroy of the H.S.S Beagle
• Two year voyage to chart the coastline of South
America
Movie
Sailing the Seas…for five years!
Darwin – the voyage!
• Darwin methodically collected an
enormous amount of specimens
– Animals, fossils, rocks, etc.
• He also made observations and took
detailed notes
• Some key specimens from the
Galapagos Islands…
Darwin’s Finches
Galapagos Islands…great place to visit?
Blue-footed Booby
Galapagos Tortoise
Iguanas
Galapagos
Islands
What did he see & find?
• He saw:
– Living Organisms and Fossils
• Fossil: preserved remains or evidence of an
ancient organism
– Patterns of diversity: organisms are different
all over the world and on different islands of
the Galapagos
• Patterns of diversity example:
Darwin’s Finches
Other Scientists that shaped
Darwin’s Ideas
1. Hutton
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Layers of sedimentary rock form slowly
Mountains are pushed up slowly
The earth changes slowly!
2. Lyell
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Darwin read his book right before sailing on the
Beagle
Volcanoes and erosion we see working today takes
millions of years to make the landscape
The earth is older, much older than we think
Other Scientists that shaped Darwin’s Ideas
3. Malthus
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Population growth and food production are related
Overpopulation will occur
There will always be competition for food.
Those that get food are the most advanced
genetically
4. Lamark
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1st to propose a theory of evolution, but his was
WRONG!
1. Tendency towards perfection
2. Use and disuse of organs: if you stop using an
organ, it will disappear
3. Passing on acquired traits: traits you get in
your lifetime will be passed on to your
offspring
•
Alfred Wallace writes Darwin
–
•
He came up with the same ideas
independently (“I think an organisms
structure is related to the environment it
lives in”)
This forced Darwin to publish his book,
On the Origin of Species, in 1859
–
21 years after the Beagle voyage!
Movie
So what is Darwin’s Theory?
1. There is variation within a species
2. Some traits are helpful, some are harmful.
Those that are helpful will help the
organism survive. Those that are harmful
will cause the organism to die sooner.
(natural selection)
3. Those that survive will reproduce others
with the same traits
4. Over a LONG period of time, the species
gradually changes.
5. All living organisms originated from one
common ancestor.
Natural Selection (after genetics)
• Genetic mutations occur
during meiosis.
• Over time, natural
selection causes changes
in the inherited
characteristics of a
population (the gene
pool).
• Changes lead to
adaptations and eventually
new species!
Movie
V
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Variation: The differences in
individual organisms in the same
species.
Same
Species?
Marine
Flatworms
snails
Variation- differences
• Variation is caused by:
–Sexual reproduction (“shuffling
the genetic deck”)
–Genetic mutations (error in DNA
replication or repair)
Ex: Variation in height among
humans
Example: Peppered Moth
• Black and White
variations
• Live mostly on white
birch trees in England
• Birds eat them!
• Birch trees turned black
from soot from nearby
factories
• Which moth was more
likely to survive?
Simulation
Survival of the Fittest = Natural Selection
• Species Overproduce—
Most species produce more
babies than can survive
• Struggle for existence—
Members of each species
compete on a daily basis for
food, living space, and
other necessities
• Fitness—the ability of an
individual to survive and
reproduce in its
environment
• Adaptations- inherited physical
features or behaviors that become
common in a population because it
provides a natural selection
advantage
Many animals are browns
and grays. Why??
Some fish lay on the sand
to camoflage.
A deer will lift its white tail
to warn others
of danger.
Even eggs and babies can be
camoflaged.
Sometimes an animal will hi-lite
one body part to save another.
Phototropism
-plants grow
to light.
Plants have adaptations, too.
How is the Ghost Pipefish adapted to
its’ environment?
video
Lesson Overview
Evolution as Genetic Change in Populations
How do variations become Adaptations?
Normal Variation exists as a “bell shaped curve”.
Variations become adaptations when they “increase the
chance for survival”.
Lesson Overview
Evolution as Genetic Change in Populations
Directional Selection
Directional selection occurs when individuals at one end of
the curve have higher fitness than individuals in the middle or
at the other end. The range of phenotypes shifts because
some individuals are more successful at surviving and
reproducing than others.
For example, if only large
seeds were available,
birds with larger beaks
would have an easier
time feeding and would
be more successful in
surviving and passing on
genes.
Lesson Overview
Evolution as Genetic Change in Populations
Stabilizing Selection
Stabilizing selection occurs when individuals near the center
of the curve have higher fitness than individuals at either end.
This situation keeps the center of the curve at its current
position, but it narrows the overall graph.
For example, very small and
very large babies are less
likely to survive than averagesized individuals. The fitness
of these smaller or larger
babies is therefore lower
than that of more averagesized individuals.
Lesson Overview
Evolution as Genetic Change in Populations
Disruptive Selection
Disruptive selection occurs when individuals at the upper and
lower ends of the curve have higher fitness than individuals
near the middle. Disruptive selection acts against individuals
of an intermediate type and can create two distinct
phenotypes.
For example, in an area
where medium-sized seeds
are less common, birds with
unusually small or large
beaks would have higher
fitness. Therefore, the
population might split into
two groups—one with
smaller beaks and one with
larger beaks.
Lesson Overview
Evolution as Genetic Change in Populations
Genetic Drift
Genetic drift occurs in small populations when an
allele becomes more or less common simply by
chance. Genetic drift is a random change in allele
frequency.
Speciation
If Darwin says that we all
have a common ancestor,
how do we get new
species?
Species: group of similar organisms
that can breed and produce fertile
offspring
Speciation: Formation of new
species
Members of a species may be born with
Variations- gene shuffling
Mutations- a genetic change
Sometimes those variations/mutations
are an adaptation and allow the
individual to survive.
The surviving individual(s) usually
reproduce others like them.
Those individuals without the adaptation
tend to die off.
Over a very long period of time, the entire
species can change to have the adaptation.
A necessary factor in speciation:
populations become reproductively isolated
Reproductive Isolation- separating a species in
any way so they can’t breed with each other
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•
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Behavioral Isolation- (Different courtship
rituals)
Geographic Isolation- (Separated by rivers,
oceans, mountains, etc)
Temporal Isolation- separated by time
(reproduce at different times of the year)
What kind of speciation is this?
How are these species related?
Kaibab
Squirrel
Abert
Squirrel
What kind of speciation is this?
Cicadas that
breed every 13
years
Cicadas that
breed every 17
years
What kind of speciation is this?
The eastern meadowlark (left) and western
meadowlark (right) have overlapping ranges. They
have different mating songs.
Speciation in Galapagos Island
finches
The steps of speciation in Darwin’s
finches
1. Bird pushed from mainland and arrive on the
islands.
2. Separation of populations
(Geographical isolation)
3. Changes in the gene pool
(Reproductive isolation)
5. Ecological Competition for survival (mainly
food)
How do scientists prove speciation
occurred? Can’t state it as a fact, only an
evidenced theory by:
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Genetic Studies
Studying fossil history
Presumed common ancestors
Observing common traits
What kind of speciation did Darwin
observe in the Galapagos?
Evolution Evidence
-How do we know it happened?
Key Concept:
Darwin argued that living things have been
evolving on Earth for millions of years.
Now we believe it has been 3.5 billion years.
Age of Earth = 5-6 billion
4 Main Proofs of Evolution
1. Fossil
Record
Fossils provide evidence that
living things have been
evolving for billions of
years.
Fossilization Video
Archaeopteryx Fossil – 150 million years old
Example:
Oldest dinosaur
fossil with
feathers –
probably evolved
into birds.
• The oldest fossils are 3.5 billion years old!
3.4-3.5 billion year old stromatolites composed of
cyanobacteria and sediment from the Pilbara Shield of
Australia
Video- 11 min
2. Geographic Distribution of Living Species
• Darwin saw similar
organisms in different
locations.
• He thought: Can these
organisms adapt to
their local
environment and
change over time?
Beaver
Muskrat
Beaver and
Muskrat
Coypu
Capybara
Coypu and
Capybara
3. Similarities in Body Structure
a. Homologous structures – parts of
different animals that develop from the
same body part but have different
functions.
Examples: human arm, cat leg,
whale fin, bat wing
b. Vestigial Organs – organs that
serve no useful purpose. So why
are they there?
Organs like: tonsils, appendix,
coccyx, wisdom teeth, whale
pelvis…
4. Similarities in Early
Development
a. Embryos
(organisms in the
early stages of
development) of
different animals
look very similar.
Why?
Why?
1. Not all genes in an organism are turned
on at the same time. They have a
specific pre-arranged order that all
living organism share.
2. As embryos grow, different genes turn
on to make them different organisms.
What about Us???
Human Evolution
We have fossils of our own
species(homo sapiens)
dating back 100,000 years.
Fossils of close relatives
date back some 2 million
years. Earlier
hominids(primate that
walks on 2 feet) date back
to 6 million years
Human Evolution
• Australopithecus
afarensis- 3 million
years ago. Very
small skull. Oldest
full fossil
reconstruction
found thus far.
Human Evolution
• Australopithecus
africans- 2 million
years ago. Apelike, but bipedal
locomotion.
• Homo habilus- 1.8
million years ago.
Handy with tools.
Human Evolution
• Homo Erectus-
0.5 million years ago.
Thought to be first
erect mammals.
Wrong!
- Java Man
- Peking Man
Human Evolution
• Homo sapiens
- Neanderthal Man100,000 years ago.
Short, tough hunters.
• Homo sapiens(cont.)
- Cro-Magnon50,000 years ago.
Hunters and artists.
Cave paintings.
- Modern humans10,000 years
ago. (us)
That’s the story according to
scientists, anthropologists and
paleontologists
So, there are 2 big questions:
• Did species evolve? Do they
continue to evolve?
• If so, what has caused the
changes in species?
Darwin’s Theory of Natural Selection was widely accepted
from 1860-early 1900’s by those who thought evolution had occurred.
1920’s: Scopes Monkey Trial
Met by a new
challenger, organized
religion and the
creation theory.
Creation Theories
A force other than the
natural laws of science
causes evolution to occur.
A creation theory may
take many forms:
Organized religions
(Christianity,
Buddhism, Muslim,
etc.) or just a personal
belief.
Today- 2014
Both creationism and natural selection
remain popular theories to explain why
and how nature has changed. Many
people combine both theories!
What do you think??
Evolution....
a slow
gradual
process that
... well,
Evolves!!