Download Chapter 7 notes

10/15/12 “Mutations” – INB P. 79
Sponge: The DNA fingerprint for a
mouse is ATCGATGCA, an
elephant shrew is CGTTAAGCC,
and an elephant is CATTAACGG.
1. What would the other rung of the
DNA ladder look like for each
organism?
Mouse-TAGCTACGT, elephant
shrew-GCAATTCGG, elephantGTAATTGCC
2. Which two organisms would be the
most closely related? Explain.
Elephant and the Elephant Shrew
because their DNA sequence is
more similar than that of the mouse.
10/16/12 “Build a Beast” INB P. 81
Sponge: P. 177: 1. Explain the
relationship between an organism's
adaptation and evolution.
Organisms that have beneficial
adaptations survive better than other
members of the same species.
2. How is your answer for number one
similar to Darwin's theory of Evolution
by Means of Natural Selection?
It is the same. Darwin says that these
organisms survive and are more likely
to produce offspring with the same
adaptations.
10/19/12 “Natural Selection” INB P. 87
Sponge: P. 177-178: 1. Explain the
relationship between mutation and
variation and how do these terms
influence evolution?
Mutations cause variations among
offspring that are acted on by
natural selection.
2. Explain how species change
over time and become better
adapted to conditions.
Some offspring inherit beneficial
mutations that are passed on to
their offspring.
Natural Selection Mini-Lesson
1. What color is the bark of coniferous
trees?
Black or dark brown
2. What color is the bark of deciduous
trees?
Gray or gray brown
3. What biomes are gray squirrels found in?
They are found in deciduous and coniferous
forest biomes.
4. How does natural selection determine
which squirrels survive in which biome?
The squirrels that are the most camouflaged
for the biome are the ones that survive.
Natural Selection Mini-Lesson Cont’d
5. Darwin uses the term
“survival of the fittest”. What did
he mean by this term?
The organisms with the best
adaptations for the environment
survive and produce offspring.
6. What are the two niches of
gray squirrels?
Finding food and avoiding
predators.
7. How do you think trees
benefit from the gray squirrels?
Gray squirrels plant trees.
10/17/12 “Bird Beak Adaptations” INB P. 83
Sponge: P. 173: 1. What observations
did Darwin make and when did he
make them?
The diversity of living things, the
remains of ancient organisms, and the
characteristics of organisms on the
Galapagos Islands.
2. How do you think evolution is
different from this idea?
Evolution is the idea that all living
things have changed over time to
become better adapted to the
environment.
Take a few quick notes about evolution:
Earth is approximately 4.6 billion years old, and the
planet has changed a great deal during its existence.
For organisms to survive, they would have to change
(mutate) also. A mutation is any permanent change in
the DNA of a gene or chromosome.
Some mutations are BAD, some can be GOOD and
some don’t really have any effect.
Examples of mutations: Albinism
Other Mutations…
Some mutations lead to adaptation…
When a mutation is beneficial and helps an
organism to survive in its environment, the organism
has the opportunity to live a long life, find a mate,
and pass on its beneficial traits to its offspring.
For example, a zebra’s stripes allow it to confuse
predators when traveling in herds. This allows them
to survive another day to pass on their traits during
reproduction.
An adaptation is a characteristic that helps an
organism survive and reproduce in its
environment. They include structures and
behaviors for finding food, a mate, for
protection, and for moving from place to place.
Charles Darwin
Charles Darwin, studied the characteristics of organisms in the
Galapagos Islands and noticed that they were similar to those
on nearby South America. He hypothesized that animals came
to the Galapagos from the mainland. The environment
determined which animals would survive and which would die
off. Those adapted to the new environment survived and
became different from their mainland relatives.
Example: Iguanas & Finches
Bird Beak Adaptation
Activity
Pre-lab questions
1. How do birds adapt to their environment?
Beaks adapted to food source, special feathers
for type of flight, special claws or eyesight
for hunting, feather colors, etc.
Purpose: How does the shape of a bird’s beak
helps decide what it can eat?
Hypothesis: Match the “bird beak” on the left
with the “food item” it may be best suited for
picking up on the right
Bird Beak
Food Item
Tweezers
Pasta
Spoon
Paperclips
Fork
Marbles
1.
2.
3.
4.
5.
6.
Procedure:
Select a beak from the objects provided by your
teacher
Get one plastic cup filled with “food” and empty it out
slowly in front of you on a paper plate. There are 20
food items in each cup. The empty cup now
represents your “stomach.”
One student will hold the beak and one student will
hold the stomach.
When your teacher tells you, use your beak to pick
up the “food” at your lab station and place them in
your “stomach” one item at a time. You will have 20
seconds to get as many food items as possible.
When your teacher says “Stop,” empty your stomach
and count the number of food items that were
collected. Record your number in your “Bird beak
data table” in your notebook.
Swap materials and continue until your table is full
What type of bird would have beaks similar to
the ones we used in class today?
a.
b.
c.
d.
e.
Nectar sipper (sunbird)
Insectivore (flycatcher)
Grain eater (Grosbeak)
Seed Eater (Crossbill)
Fishing/piercing
(Kingfisher)
f. Netting fish (Pelican)
g. Filter feeder (Flamingo)
h. Surface Probing (Avocet)
i. Probing worms (Ibisbill)
j. Surface Skimming for fish
(Skimmer)
k. Raptor (Harris Hawk)
10/22/12 “Butterfly Blending” INB P. 89
Sponge: Watch the movie
“Masters of Disguise” and
answer the following question.
1. How do birds find caterpillars?
By looking for leaves with holes in
them.
2. How does the hornworm
caterpillar “cover it’s tracks” to
avoid predators?
It chews the leaf quickly and
evenly.
Now you see me, now you don’t!
Traits are inherited and some traits make it easier
for living things to survive and reproduce.
Camouflage is a trait that makes it very hard to
see an animal in its natural habitat. Camouflage is
an important part of their survival. It hides the
animal from its predators while, at the same time,
making the animal a sneaky predator itself.
An animal that is best camouflaged in its
environment has the best chance to survive,
reproduce, and pass its color pattern on.
Natural Selection Example: The Peppered Moth
There are two phenotypes for a type of moth found in
England: black and white speckled.
Before the Industrial Revolution, the white “peppered
moth” was had the largest population because they
matched the light colored bark on the trees. This meant
that birds couldn’t spot them and eat them, so they lived.
longer.
The Peppered Moth
When the Industrial Revolution
happened, the factories poured out
black smoke, covering the white trees
with black soot. This caused the white
moths to stand out, and the birds ate
them sooner than the black ones. The
black moth population then grew
rapidly because the birds were not
naturally selecting them. If this
progression were to continue for
generations and generations, the gene
for the white moths may be completely
eliminated from the species. In other
words, the birds would cause all of the
white moths to go extinct because of
evolution.
Concealing Coloration – when an
animal blends in with its
background
Octopus Video
Disruptive coloration – when an
organism’s color is broken up with
other patterns like stripes or spots
so it doesn’t stick out against the
background
Mimicry – when an animal copies
or mimics a color or form of
something else.
Blending Butterflies
Purpose: To explore and simulate camouflage in
animals
Materials: Butterfly pattern, colored pencils, markers or
crayons
Procedure:
1. Write your name on the back of your butterfly.
2. Design a butterfly so that it can be
hidden/camouflaged somewhere in the classroom.
3. Make the butterfly as invisible as possible.
4. Cut out the butterfly. Tape the butterfly to it’s
hiding spot.
Natural Selection
In our Blending Butterflies activity,
you were able to show how
natural selection works. Those
butterflies that blended in have
the traits that help them to
survive. Those that didn’t blend
in, do not have those traits.
Organisms that do not have the
necessary traits to survive in the
environment will not live as long
as those that do have the traits.
Therefore, they will not be able to
reproduce as much as the
organisms that live a long time.
More organisms with the desired
traits will live from generation to
generation. This process is
known as natural selection.
Factors that can affect Natural Selection:
Overproduction - more offspring = fewer resources
Variations – if there is no variation, all species will have the
same traits and an equal chance of surviving and reproducing.
Competition - organisms compete or fight over resources
Selection - favorable traits are more likely to be passed on
while unfavorable ones disappear
Environmental change - changes in the surroundings
10/18/12 “Who Wants to Live a Million Years” INB P. 85
Sponge: P. 177-178: 1. What
factors did Darwin identify that can
cause natural selection?
Overproduction, competition, and
variations.
2. How would competition for food
during an ice age result in natural
selection?
Organisms that are best adapted to
finding food will survive and
produce offspring and those that
aren’t adapted will die.
Remember that Natural
Selection is what
DRIVES EVOLUTION!
Let’s see natural
selection and evolution
in action as we play
“Who wants to live a
million years?”
Complete the activity
on the front of your INB
sheet as we go through
this interactive
evolution website.
10/23/12 “How Old is that Fossil?” INB P. 89
Sponge: P. 173: 1. What is a fossil
and why was Darwin puzzled by
them?
Fossils are the preserved remains or
traces of an organism. He was
puzzled because the fossils he found
were similar but much larger than
organisms alive today.
P. 184: 2. What are homologous
structures? Give an example.
Similar structures that related species
have inherited from a common
ancestor. Ex. The arm bones of a
human, cow, horse, whale, and bird
are the same.
Evidence of Evolution: Fossil Record
Fossils are the solidified remains or imprints of
once-living organisms. Most fossils are found in
the layers of Earth. The older a fossil is, the
further down in the rock layer it is. Organisms that
resemble the living creatures of today are mostly
found in top layers, while more ancestral forms
are found lower in the rock layers. This is called
relative dating.
How old is that fossil?
We can estimate an AGE of a fossil using
absolute dating: Rocks contain
radioactive chemicals that break down.
The half-life is the amount of time it takes
for half of the chemicals in a rock to
decay, and turn into another chemical. We
analyze a sample of the chemical from a
radioactive rock found near the fossil to
determine how old the fossil is.
Reading the Fossil Record
•
•
Fossils found in the upper, newer layers of
Earth resemble the organisms of today.
Deeper fossils look less like present-day
organisms.
We use these fossils to trace the evolutionary
history of organisms.
Gaps in the Fossil Record
•
•
•
•
Not every organism leaves a fossil
No fossils = gaps in the fossil record
Scientists call the gaps “missing links”
If missing links are found, they may
connect an older species to a more recent
one
• Gaps can be caused by:
– Mass extinctions –entire species die off
– Rate of evolution - scientists are not sure
if species change gradually or quickly
Half-life Activity
Different chemicals have
different half-lives. For our
example, we are going to
use carbon-14. Carbon-14
is a radioactive element.
This means that it is an
unstable substance. The
atoms of carbon-14 change
to another element,
Nitrogen. It takes about
5,700 years for half of the
atoms in a sample of
carbon-14 to change to
stable nitrogen. This period
of time is known as the halflife of carbon-14.
All living things contain
carbon-14. Plants take-in
carbon dioxide during
photosynthesis and
therefore also take-in
carbon-14. When animals
eat the plants, the carbon-14
is transferred to the animals.
When a plant or animal dies
(they are no longer taking in
carbon), the carbon within it
begins to change (decay) to
nitrogen. After a while, all of
the carbon-14 will decay to
nitrogen.
1. Draw 100 dots in box 1. After 5,700 years, if it is cut in half, how many
dots should I have left? Draw the new amount of dots in box 2.
2. What would happen after box 2 if another 5,700 years passed (box 3)?
Would all the dots be gone?
For each half-life draw the number of dots that would be left as you go
through each box.
3. Then after 5,700 more years (box 4) how much would be left?
4. a. If something died 5,700 years ago how much of a percentage is left?
b. If it has been 11,400 years how much is left?
c. 17,100 years?
5. Using boxes1-6 above, how many total years have passed since this
organism died?
6. What would be the amount left if another 5,700 years passed after box 6
(box 7)?
Notice how after a little while it becomes so small that we can hardly see it
anymore. That is the point at which carbon dating is no longer useful. So we
need to find something with a longer half-life to date older things. We use
ones with VERY long half-lives to date the earth.
You have recently discovered the
fossilized remains of a woolly
mammoth. On the piece of
paper in front of you, draw
your best woolly mammoth.
Be sure to fill up the whole piece
of paper. This will represent all
of the carbon-14 that was
present in the woolly mammoth
when it died. Cut the sample in
half. Continue cutting one-half of
your mammoth in half, again and
again until the box is so small
that it is not possible to make
another cut. Each time you
make a cut, make a mark in the
box on your paper below.
Conclusion Questions
1. What is the total number of times you were (practically) able
to cut the sample in half?
2. Each cut represents the half-life period of carbon-14. What
is the length of time represented by each cut?
3. Multiply the number of cuts by the half-life period of carbon14. What is the total amount of time represented by all of
your cuts?
4. If an animal lived near and died in the LaBrea Tar Pits (found
now in Los Angeles, California) 40,000 years ago, could
carbon-14 be used to determine when it died?
5. If an animal lived millions of years ago, could carbon-14 be
used when it died? Why or why not?
6. If the initial amount of carbon-14 in the mammoth was 8
grams, how many half-lives have passed if the fossil sample
has 1 gram left? How may years have passed since the
mammoth’s death?
10/24/12 “Evolution of the Whales” INB P. 93
Sponge: P. 183-184: 1. How do the
similarities in early development
provide evidence of evolution?
A dorsal hollow nerve chord, a tail,
and gill slits provide evidence for a
common ancestor among
vertebrates.
2. How are the structures of
dolphin's flipper, a bird's wing, a
dog's front leg, and a human arm
similar?
They all have the same bones, a
humerus, radius, ulna, and
phalanges.
Whales are mammals, just like you, and
their ancestors once lived on land. How do
we know this? There are several ways that
we can determine if organisms are related to
one another.
Homologous Structures
Sometimes, scientists can look at the
homologous structures shared by the two
organisms. Remember that a homologous
structure is a structure that shows how certain
species have inherited a trait from an ancestor.
The human arm, a bird’s wing, a dolphin’s pectoral
fin, a dog’s front leg, and even a whale’s fin all
have a very similar bone structure.
Missing Link: The Archaeopertyx
Similarities in DNA
We can also compare the DNA to note how many base
pairs match up. Our DNA and a chimpanzee’s are 99%
the same, demonstrating that we are related to one
another.
Evidence of Evolution: Comparing Organisms
Another method that scientists use to provide evidence
of relatedness and for evolution is embryological
evidence. We can observe the embryonic development
of various species of organisms to see if they are
related. For example, the chart above shows the
development of a fish, lizard, dog, chicken, and human.
Although they are not all mammals, they all share
related development because they are all vertebrates –
they have a backbone.
Anyhow, back to the whales… so how did
they come to live in the ocean? On the
inside of your sheet, you will see steps to
reconstruct the evolution of the whale from
land to sea. Read the descriptions and use
the traits drawn on the front to help you draw
the journey of the ancestral whale to present
day.
Evolution of the Whale
Based on the fossil record, and because whales
are air-breathing mammals, scientists believe
that they must have descended from a land
dwelling mammal, such as the Mesonychid that
lived near the ocean 55 million years ago.
Evolution of the Whale
Mesonychid evolved into a wolf-sized meat-eater
called Pakicetus. Pakicetus ate primarily fish.
These animals were fur covered and had a head
that was becoming whale-shaped with sharp
teeth. They lived near the ocean 50 million years
ago.
Evolution of the Whale
Eventually, the Pakicetus developed into another land
dwelling animal with shorter legs and webbed feet called
the Ambulocetus (48 million years ago). This animal
was able to swim well due to webbed feet and was
therefore able to survive off of the abundant supply of
food in the ocean (natural selection.) Ambulocetus’
head is long and narrow and resembles a lizard’s.
Evolution of the Whale
Rodhocetus appeared in the fossil record 46 million
years ago. This animal resembled modern whales, but
had four legs like a land dwelling animal. It’s hind legs
were reduced (smaller) and it’s tail had a modified fin
at the end, making it a better and stronger swimmer.
It’s forelimbs are now fused together as a primitive
flipper, and it’s head is similar to an alligator in shape.
Evolution of the Whale
Basilosaurus isis lived 37 million years ago. It’s
body was more elongated and the modified tail
became wider at the end, making it an even
stronger swimmer. The hindlimbs are very
reduced and barely visible as small flipper-like
appendages. It’s head was similar to a dolphin in
shape.
Evolution of the Whale
Basilosaurus evolved into the most recent
ancestor of the modern-day whale, the
Dorudon. Dorudon lived 34 million years
ago and lived strictly in the sea. Their
nostrils moved to the top of the head to
become the blowhole and its forelimbs are
paddle-like flippers. The hindlimbs are
absent.
Let’s see evolution in action!
Watch as the whale ancestor’s
you just created evolve into a
modern day whale!
10/26/12 Bill Nye, “Evolution” INB P. 95
Sponge: P. 186-187: 1. How do new
species form?
When a group of individual remains
isolated long enough from the rest
of the species to evolve different
traits.
2. Why do scientists believe that the
Kaibab squirrel and Abert's squirrel
will one day form two different
species?
The two squirrels are seperated by
the grand canyon and will one day
evolve different traits through DNA
mutation to form new species.
Bill Nye: Evolution
Now watch
this segment
with Bill Nye
as he
discusses
Evolution!