Transcript Natural Selection and Adaptations - pams

Natural
Selection and
Adaptations
What’s up with that bird?
Vocabulary
•Adaptation
•Natural Selection
•Mutation
1.Scientists believe that the Earth
and its inhabitants have changed
a great deal over time.
-They have observed species’
fossil records and have noticed
changes over time.
-Organisms tend to adapt or
change over time.
2. Adaptation- a change in an
organism that helps it live and
reproduce successfully in its
environment.
-these adaptations can be physical or behavioral
long neck or stripes
Reproduction, protection,
or finding food
http://www.lawrencehallofscience.org/kidsite/portfolio/build-a-fish/
3. One scientist that observed these
kinds of differences in plants
and animals of the same
species is Charles Darwin.
In 1831 Darwin sailed
on board the SS Beagle
from his home in
England to a small
island group off the
coast of Ecuador
4. Darwin traveled to the Galapagos
islands where he saw plants and
animals that differed from those on
other islands and the mainland.
Examples: tortoises
long neck versus short neck
Live in dry climates with cacti
Live in damp area with
abundant plant life
5. Darwin also found different types
of finches (birds). He noticed
different beak shapes and sizes from
one island to the next.
Woodpecker finch
Vegetarian finch
Large ground finch
Cactus finch
There are at least 13 species of finches, each with a
different niche. All are said to have come from the
same ancestral species, which only got to the islands
about 2 million years ago. This is known as adaptive
radiation-where one species quickly changes or adapts
to fill in the “empty” ecospace.
6. When most plants and animals
reproduce, they usually produce more
offspring than can survive.
Example: salmon
-lay 1000’s of eggs, but not all will hatch. Of those that do
hatch, only a fraction will survive disease and avoid fish eating
predators.
Only a small % of these survivors will make
it to adulthood, with only a few being able to
reproduce successfully.
7. From one generation to the next
there are always variations.
These genetic
variations are
passed down.
http://phet.colorado.edu/en/simulation/natural-selection
-run now version
8. A change in genetic material is called
a mutation. Some mutations make the
individual better able to survive.
Camouflage an adaptation or a
mutation?
-Moths will rest during the day
Time: late 18th/early 19th century -Black moth coloration
considered a mutation
Place: Pre-industrial England
Subject: Biston betularia or the peppered moth
Before industry-trees had gray trunks-gray moths blended in better.
After industry developed-tree
trunks turned black due to the
pollution from factories-black
moth was then able to blend in
After many, many generations of
this, most moths were then black.
In this case coloration is
considered to be an adaptation.
Moths
Peppered Moth Simulation
• Objectives: Describe the importance of coloration in avoiding predation
Relate environmental change to changes in organisms (adaptation)
Explain how natural selection causes populations to change
• Materials:
Sheet of white paper
Newspaper
Forceps
Colored Pencils
Clock or Watch with Second Hand
30 newspaper circles (made with hole punch)
30 white circles (made with hole punch)
• Purpose: In this lab, you will simulate how predators
locate prey in different environments. You will analyze
how color affects and organism's ability to survive in
certain environments.
Copy this data table into your lab notebook
Peppered Moth Simulation
Starting Population
Trial
Back
ground
News
paper
White
1
white
30
30
2
white
30
30
3
News
paper
30
30
4
News
paper
30
30
Number
Picked up
White
News
paper
Introduction: Industrial Melanism is a term used to
describe the adaptation of a population in response to
pollution. One example of rapid Industrial Melanism occurred
in populations of peppered moths in the area of Manchester,
England from 1845 to 1890. Before the industrial revolution,
the trunks of the trees in the forest around Manchester were
light grayish-green due to the presence of lichens. Most of the
peppered moths in the area were light colored with dark spots.
As the industrial revolution progressed, the tree trunks became
covered with soot and turned dark. Over a period of 45 years,
the dark variety of the peppered moth became more common.
Procedure:
1. Place a sheet of white paper on the table and
have one person spread 30 white circles and 30
newspaper circles over the surface while the other
person (or “predator”) isn’t looking (eyes closed).
2. The "predator" will then use forceps/tweezers to
pick up as many of the circles as he/she can in 30
seconds.
3. Without putting the circles back between trials,
repeat with white circles on a newspaper
background, newspaper circles on a white
background, and newspaper circles on a newspaper
background. Record your data in the chart.
Peppered Moth Simulation
Starting Population
Trial
Back
ground
News
paper
White
1
white
30
30
2
white
30
30
3
News
paper
30
30
4
News
paper
30
30
Number
Picked up
White
News
paper
Analysis
1.What did the experiment show about how prey are
selected by predators?
2. What moth coloration is the best adaptation for a dark
(newspaper) background? How do you know?
3. What would you expect the next generation of moths
to look like after trial 1? What about the next
generation after trial 3?
4. How does the simulation model natural selection?
5. Imagine a second mutation (clear or colored circles)
caused a third population to arise, what affect do you
think it might have on the other two populations of
moths?
5. Examine the table and construct a graph. Plot the years of
the study on the X-axis, and the number of moths captured on
the Y axis. You should have 2 lines on your graph - one for light
# of Light Moths
# of Dark Moths
Year
moths, and one for dark moths.
Captured
Captured
Use the ½ sheet of graph paper
2
537
112
3
484
198
4
392
210
5
246
281
6
225
337
7
193
412
8
147
503
9
84
550
10
56
599
6. Explain in your own words what the graph shows.
7. Describe a situation where this type of selection might occur.
9. If this organism is able to survive
and reproduce, the mutation is passed
on to future generations.
This is called selective
breeding
http://www.pbs.org/wgbh/nova/evolution/evolution-action.html
Example: Terriers bred to show certain characteristics
10. This idea led to the Darwin’s
theory on Natural Selection.
11. Natural Selection: the process by
which organisms that are best suited
to their environment survive and
small marine iguana on
reproduce. Example:
an island with a thin layer of algal
growth
http://media.nclive.org/authvid.phtml?vid=203&ctime=6
Voyage to the Galapagos video and questions (~60 minutes)
Who wants to live a million
years?
http://science.discovery.com/interactiv
es/literacy/darwin/darwin.html
Introduction. Scene - On a distant planet there exists 5
species of a creature called a Woolybooger. Each
Woolybooger is similar except their mouth has
variations. All woolyboogers eat beans. Some
woolyboogers have a clothespin mouth (look at how to
use the clothespin to pick up beans).
Some woolyboogers have a tweezer mouth (as
demonstrated), some have a needle mouth (as
demonstrated). One year a new species of woolybooger
was discovered, this woolybooger was called the SpoonMouthed Woolybooger (as demonstrated).
Each of you will play the part of a woolybooger on this
planet. The spoon-mouth wooly booger is rare, so only
two of you will get to be this type of woolybooger.
Survival of the Woolybooger
• Overview - Students will model natural selection by using various
utensils to "capture food"
• Materials:
3 bags of beans (northern or lima)
10 trays
10 plastic spoons
10 tweezers
10 clothespins
10 rounded toothpicks
•At this point, I will pass out the utensils and give each group a
tray with beans. The entire group will share bean trays but
each person should have their own utensil.
•There is no "cheating", you must use your utensil in the way
they are intended to be used (as I demonstrated).
•We will do several rounds. Each trial will require your
Woolybooger to gain at least 20 beans. If 20 beans are not
acquired during the time period, your Woolybooger has died.
•We will start with 1 minute.
Discussion Questions:
1. What happens to animals that cannot compete as well with
other animals in the wild?
2. Can you think of any real-life examples of the woolybooger,
where one species has a definite advantage over another?
3. Sometimes animals that are introduced into an area that they
never lived in before, out-compete and endanger resident
species, why do you think this happens?
4. If only one species is considered the "fittest", why do we still
have so many variations among species. Why do some birds
have very long pointy beaks, while other birds have short flat
beaks?
5. How do you think diseases can affect natural selection?
Darwin’s Finches
Adaptation occurs in an ecosystem so that species can
better survive in their habitat. Sometimes these
adaptations cause competition between species
allowing one species to thrive while the other dies out.
A good example of this type of adaptation
occurs on the Galapagos Islands with the
finches that inhabit the area. Each species
of finch has a specific body weight, beak
shape and eating habits that allows them to
avoid competing for food with the other
finches.
Birds of a beak activity
In this activity you represent finches with four
different beak types. You may only use your beak to
gather food to put in your “stomach”.
First, we will try to determine what kind of food your
beak type would like best. You’ll try each of the
different food types one at a time and then record
the amounts in lab notebook data table.
Table 1
Record the total number of each food item in
your “stomach”
Finch type
Large Binder
Medium
Binder
Small Binder
Spoon
Number of
finches
Popcorn
Marbles
Beans
Blocks
Paperclips
Toothpicks
1. You will need to have an area that is approximately 2 feet
by 2 feet (one desk top).
2. Each person in the group will have a different type of
beak.
3. Scatter the contents of one cup of “food” into the marked
territory (this is your island).
4. When the teacher announces, you will have 2 minutes to
gather as much food as you can.
5.The food has to make it to and stay in your stomach in order
to count. Once in your stomach no one can take it from you.
Second, a mixture of food will be placed on your table and you have to
see how many of the different beaks survive. You do this by adding up
the number of calories you get (use the chart below) and comparing that
to the number of calories you need to live.
Calories each food is worth:
Marbles – 50 calories
Beans - 20 calories
Paper clips – 15 calories
Toothpicks – 10 calories
Blocks –30 calories
Popcorn - 10 calories
Calories each finch needs to
live:
Large binder clip- 300 calories
Spoon- 250 calories
Medium binder clips- 150
Small binder clips- 100
Table 2
Record the number of each food item you
collect from the food mixture. At the end, calculate the
caloric intake of each beak. Did your finch survive?
Finch type
Large Binder
Medium
Binder
Small Binder
Spoon
Popcorn
Marbles
Beans
Blocks
Paperclips
Toothpicks
Calories
Did You Live?
Birds of a Beak Conclusion
Questions
• From situation 1, which beak was best adapted?
Which was least adapted?
• Which food item could be eliminated and not
effect the population of finches?
• From situation 2, if food was in low supply-which
food item could your finch survive off of?
Evolution Lab
In this lab, you will use a computer simulation to track a
population of organisms as they evolve. You will take data on the
number and varieties of the organisms and graph them to show
change over time and determine how two factors: MUTATION
RATE and SELECTION STRENGTH affect how populations
evolve.
Instructions
1. Go to www.biologyinmotion.com and click on the link that says
"evolution lab"
2. Read the introduction and the contents to learn about the
imaginary creatures you will be studying and how to operate
the simulator. You may also want to look at the help link.
3. Open the simulator and practice using the controls before
you go on to the real simulation. Be sure to "reset" the
simulator when you're finished practicing.
http://biologyinmotion.com/evol/index.html
Simulation A - The purpose of this simulation is to determine
how the mutation rate affects the evolution of your population.
You will need to run 4 trials with varying settings for mutation
rate.
Fill out the Data Table and create a graph using the graphing
program at . You will have 4 lines on your graph. The X-axis
will be cycles, and the Y will be mean phenotype.
Simulation B - The purpose of this simulation is to determine
how selection strength affects the evolution of your population.
Run three trials with the selection strength at 0, and three trials
with the selection strength at varying ranges. (See data table)
Fill out the data table and create a graph for simulation B.
Graphing Program located at:
http://www.nces.ed.gov/nceskids/graphing
Blank Data Tables (doc)
Analysis
Answer the following questions on a separate page, title this page
"Evolution Simulation" and make sure your name is on it. You can even type
it in Word if you like.
1.Describe how the simulation models natural selection (and evolution).
2. Explain HOW the mutation rate affects the evolution of your
populations.
--> Explain WHY the mutation rate affects the evolution of your
populations.
3. Explain HOW altering the selection rate affects the evolution of your
populations. (You may want to include an explanation of what "selection
strength" means.)
--> Explain WHY altering the selection rate affects the evolution of your
populations.
At the end of this web activity, you will have turned in the following documents:
•Data tables
•2 Graphs
•Analysis Questions
Credits: Special thanks to Leif Saul, author of Biology in Motion and the creator of the Evolution Lab.