Transcript Evolution PPT.

Evolution
Pre AP Biology
Spring 2013
What is Evolution?
• Definition (memorize this!!) :
– Gradual change in the genetic makeup of a
species over a long period of time
• Notice the terms gradual change and time.
These changes are difficult for us to
understand because they occur across
many generations and therefore cannot
usually be observed in our lifetime. Most
changes occurred before recorded history.
What evolution is not
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Evolution is not “we came from monkeys.”
Evolution is not “how life began on earth.”
Evolution is not “the Big Bang” theory.
Evolution does not say that God doesn’t
exist.
• Evolution is not “just a theory” without any
proof.
Questions we can’t answer in
science class:
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Does God exist?
Did God create the Universe, the world, and/or us?
What is a soul?
Who goes to heaven?
What happens after we die?
None of these questions can be answered using
the scientific method and so they fall outside the
realm of science.
That doesn’t mean they aren’t good questions or that they
aren’t worth asking, but they won’t be answered in this
class.
I’m not telling you what to believe
You will not be tested on whether you think
the theory of evolution is “right or wrong”
You will be expected to know:
• the definition of evolution
• Details about Darwin and his findings
• The proof that we have of evolution (5
major categories of proof and examples of
each)
• Natural selection and how it works as a
mechanism for evolution.
Charles Darwin
• Darwin was always interested in
the natural world.
• He came from a wealthy family
and was expected to be a doctor.
• He went to college to study
medicine and hated it…he
dropped out.
• In 1827 he went to Cambridge to
study theology and become a
minister.
• Still, he was more interested in
the natural world.
Charles Darwin
Born 1809
Died 1882
Charles Darwin
• Darwin was always interested in
the natural world.
• He came from a wealthy family
and was expected to be a doctor.
• He went to college to study
medicine and hated it…he
dropped out.
• In 1827 he went to Cambridge to
study theology and become a
minister.
• Still, he was more interested in
the natural world.
Charles Darwin
Born 1809
Died 1882
The voyage that changed
everything
• At the age of 22, Darwin was hired to be a
naturalist on board a survey voyage. The
ship was the HMS Beagle.
• The Beagle was a survey ship that was
sent to collect
information about
the coastline of
South America.
The voyage that changed
everything
• At the age of 22, Darwin was hired to be a
naturalist on board a survey voyage. The
ship was the HMS Beagle.
• The Beagle was a survey ship that was
sent to collect
information about
the coastline of
South America.
Are we there yet? Reading to pass
the time:
• On the voyage he read a book by a
geologist (Charles Lyell’s Principles of
Geology)
• The book theorized that the surface of the
earth changed slowly over many years.
• Using this information, not only did Darwin
realize that the earth must be very old, but
he became convinced that the same thing
(gradual change) happened to species.
Are we there yet? Reading to pass
the time:
• On the voyage he read a book by a
geologist (Charles Lyell’s Principles of
Geology)
• The book theorized that the surface of the
earth changed slowly over many years.
• Using this information, not only did Darwin
realize that the earth must be very old, but
he became convinced that the same thing
(gradual change) happened to species.
What he observed on the voyage
• The animals and plants in South America
looked more like each other than the
plants and animals in similar climates in
other parts of the world.
• S. A. fossils looked like current S. A.
plants and animals.
• Plants and animals found on islands close
to South America (Galapagos Islands)
were similar to the ones on the mainland.
Galapagos Islands
After the voyage
• Darwin returned from the voyage and studied his
notes along with other scientists’ essays.
• Published his observations in a book On the
Origin of Species by Means of Natural Selection
in 1859.
• The book had 2 major points:
– Organisms have changed over time (Darwin called
this “descent with modification”. We call it evolution)
– Organisms change because of natural selection.
After the voyage
• Darwin returned from the voyage and studied his
notes along with other scientists’ essays.
• Published his observations in a book On the
Origin of Species by Means of Natural Selection
in 1859.
• The book had 2 major points:
– Organisms have changed over time (Darwin called
this “descent with modification”. We call it evolution)
– Organisms change because of natural selection.
Natural Selection
• Darwin studied Artificial Selection – We
have bred animals and plants to suit
purposes…we select the traits we like.
Natural Selection
• Natural selection is also called “survival of the
fittest.”
• Natural Selection says that individuals that
have physical or behavioral traits that better
suit their environment are more likely to
survive and reproduce than those that do not
have such traits.
• In order to work the following conditions have to
be met:
– Harsh environment
– More offspring than can survive
– Variation within the offspring
Proof of Evolution
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1.
2.
3.
4.
5.
Five major points that we use to support
the theory of evolution:
Fossil Record
Homologous Structures
Vestigial Organs
Amino Acid sequences
Embryology
Fossil Record
Evolution can be seen in the
fossil record.
Darwin predicted and we
have found thousands of
“transitional forms” that
link ancestors and current
organisms.
Examples: page 284 and
285 in your book
Also horse transitional forms
Fossil Record
Archaeopteryx
Significant because it
shows the transition
from reptile to bird.
Fossil Record
Archaeopteryx
Significant
because it
shows the
transition from
reptile to bird.
Tiktaalik
Homologous Structures
• Structures that are
similar in more than
one species
• Used to support a
common ancestry.
• Example: Common
mammal forearm /
leg / flipper.
See page 286 in your book
Vestigial Structures
• Organs or structures that
are reduced in size and
seem to have little or no
function.
• Vestigial structures are
considered to be
evidence of an
organism’s evolutionary
past
• ex: Whale’s pelvic bone,
blind salamander eye
socket, our appendix, our
wisdom teeth.
Snake Feet
Amino Acid sequences.
• Look at page 287 for an example,
• Species descended from a recent
common ancestor have fewer amino acid
differences between their proteins than do
species that have a common ancestor
further back in time.
Amino Acid Sequence
• We can take amino acid sequence
differences and graph them to create a
phylogenic tree. A phylogenetic tree
shows relationships and common
ancestory using some trait (in this case,
amino acid sequences.)
Terminal = a taxonomic group; These usually represent living species, genes, or
proteins that are still around today.
Branches = the lines in a phylogenetic tree that connect terminals to nodes or one
node to another
Nodes = points in a tree where branches intersect; they the represent ancestors of all
escend from them.
MRCA (most recent common ancestor) = the latest ancestor shared by a group of
terminals;
Clades = natural groups of organisms
Tree of Life
• Tree of life video
David M. Hillis, Derrick Zwickl, and Robin Gutell,
University of Texas.
Embryology
• All vertebrate embryos
have similar structures.
• All have a tail, buds
that become limbs and
pharyngeal pouches.
• We lose the tail.
Mammals, birds and
reptiles lose the
pharyngeal
pouches…in fish and
amphibians they
become gills
Study of Natural Selection
• Find a group of 2 or 3. There is not
enough supplies for anyone to work on
their own.
• ALL of you need your own data table, a
ruler, and a pencil.
• For your group, someone should obtain a
deck of cards and a calculator from the
front of room.
Study of Natural Selection
• The cards represent the population and
the number on the card represents the
height (in feet) of the individuals.
• Jot this down in the top margin of your
paper so you don’t forget: Aces = 1 foot,
King=13 feet, Queen=12 feet, Jack=11
feet and all the others = number on card
Sampling
date
Sample
#
Height of organisms (in feet)
Average
height of
sample
1
2
3
4
5
6
X
X
X
X
X
X
X
2001 Avg.:
X
X
X
X
X
X
X
2005 Avg.:
X
X
X
X
X
X
X
2009 Avg:
X
X
X
X
X
X
X
2013 Avg:
1
2
2001
3
1
2
2005
3
1
2
2009
3
1
2
2013
3
2001 Procedure
1. Sample #1 – Shuffle the cards. Draw 6 cards
from the deck. Record the number show on
each card on the data table as height of
organisms.
2. Calculate the average to fill in last column
3. Return the 6 cards to the deck and shuffle
4. Repeat these steps 1-3 for days two and three.
(samples 2 and 3)
Sampling
date
Sample
#
Height of organisms (in feet)
Average
height of
sample
1
2
3
4
5
6
X
X
X
X
X
X
X
2001 Avg.:
X
X
X
X
X
X
X
2005 Avg.:
X
X
X
X
X
X
X
2009 Avg:
X
X
X
X
X
X
X
2013 Avg:
1
2
2001
3
1
2
2005
3
1
2
2009
3
1
2
2013
3
2005 Procedure
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1.
2.
3.
4.
During the years from 2001 to 2005 all the vegetation
below the height of 5 feet has been devoured by
caterpillars.
Remove all the cards with numbers lower than 5 (Ace
– 4). set these cards aside and shuffle remaining
cards.
Sample #1 - Draw 6 cards from the deck. Record the
number show on each card on the data table as height
of organisms.
Calculate the average to fill in last column
Return the 6 cards to the deck and shuffle
Repeat these steps 1-3 for days two and three.
Sampling
date
Sample
#
Height of organisms (in feet)
Average
height of
sample
1
2
3
4
5
6
X
X
X
X
X
X
X
2001 Avg.:
X
X
X
X
X
X
X
2005 Avg.:
X
X
X
X
X
X
X
2009 Avg:
X
X
X
X
X
X
X
2013 Avg:
1
2
2001
3
1
2
2005
3
1
2
2009
3
1
2
2013
3
2009 Procedure
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•
1.
2.
3.
4.
During the years from 2005-2009 all the vegetation
below the height of 7 feet has been devoured by
caterpillars.
Remove all the cards with numbers lower than 7. set
these cards aside and shuffle remaining cards.
Sample #1 - Draw 6 cards from the deck. Record the
number show on each card on the data table as height
of organisms.
Calculate the average to fill in last column
Return the 6 cards to the deck and shuffle
Repeat these steps 1-3 for days two and three.
Sampling
date
Sample
#
Height of organisms (in feet)
Average
height of
sample
1
2
3
4
5
6
X
X
X
X
X
X
X
2001 Avg.:
X
X
X
X
X
X
X
2005 Avg.:
X
X
X
X
X
X
X
2009 Avg:
X
X
X
X
X
X
X
2013 Avg:
1
2
2001
3
1
2
2005
3
1
2
2009
3
1
2
2013
3
2013 Procedure
•
•
1.
2.
3.
4.
During the years from 2009-2013 all the vegetation
below the height of 9 feet has been devoured by
caterpillars.
Remove all the cards with numbers lower than 9. set
these cards aside and shuffle remaining cards.
Sample #1 - Draw 6 cards from the deck. Record the
number show on each card on the data table as height
of organisms.
Calculate the average to fill in last column
Return the 6 cards to the deck and shuffle
Repeat these steps 1-3 for days two and three.
Sampling
date
Sample
#
Height of organisms (in feet)
Average
height of
sample
1
2
3
4
5
6
X
X
X
X
X
X
X
2001 Avg.:
X
X
X
X
X
X
X
2005 Avg.:
X
X
X
X
X
X
X
2009 Avg:
X
X
X
X
X
X
X
2013 Avg:
1
2
2001
3
1
2
2005
3
1
2
2009
3
1
2
2013
3
Chart and Graph your data
• In your journal you will need a chart that
summarizes your data…it should have the
average height for the population for each
year it was calculated. Remember that
charts have a title and use a straight edge.
Do not simply copy your original data
table. This one should be a summary.
Chart and Graph your data
• Underneath your chart, graph average
height in the population for each year.
Decide what kind of graph is best and
remember all the parts a graph should
have.
• Below the graph copy and answer the
questions that follow.
• This is due next class, if you don’t finish it
today.
Questions
1. If conditions described in this study remained
the same, what adaptations could you expect
from the population?
2. Explain how this lab models natural selection.
3. Why did the card with the higher numbers
have an advantage over the cards with the
lower numbers?
4. Is height always an advantage to organisms?
Why or why not. Give examples to support
your answer.
In summary
• Who? you
• Where? In your journal
• What?
– A chart that summarizes the data
– A graph of average height for each year
– Copy and answer the following questions
1.
2.
3.
4.
If conditions described in this study remained the same, what
adaptations could you expect from the population?
Explain how this lab models natural selection.
Why did the card with the higher numbers have an advantage
over the cards with the lower numbers?
Is height always an advantage to organisms? Why or why not.
Give examples to support your answer.
• When? Due next class period.
• What else? Use a ruler, give charts and graphs a title
Co-evolution
• Co-evolution occurs when 2 different
species both evolve in reaction to each
other.
• 2 great examples:
– Plants and herbivores
– Flowers and pollinators
ADAPTATION
• Remember that each species has
adaptations that help it fit perfectly into its
specific niche (location and role)
• Remember that individuals cannot adapt.
A species adapts as helpful mutations
assist some organisms in being more fit
and those mutations are passed on
•
A couple more terms
• Biogeography – A study of the geographic
distribution of organisms.
• Convergent Evolution – organisms living in the
same area evolve structures that are similar
(analogous) in spite of their evolutionary
ancestors being very dissimilar or unrelated.
• Example of analogous structures:
– butterfly and bird wing;
– fusiform shape of dolphins, tuna,sharks, and
penguins.
Forces in Evolution
• Genetic Drift – a small population will
exaggerate a difference resulting in
speciation.
– Founder’s effect
– Bottleneck effect
• Gene flow – new alleles coming into and
going out of a population