: H.2L.4 (b, e) -- Explain how biological evolution is the consequence of the interactions of genetic variation, reproduction and inheritance, natural selection and time.
First Name Last Name
Response Scoring Rubric
10 Exceeds
(excellent)
8 Meets
(proficient)
Evaluate the impact of the interactions of genetic variation, reproduction and inheritance, natural selection and time on biological evolution (change)
Explain how biological evolution is the consequence of the interactions of genetic variation, reproduction and inheritance, natural selection, and time, using multiple lines of scientific evidence.
6 Nearly Meets Describe the process of biological evolution through natural selection
Score
4 Does Not Meet Recognize that species have changed over time
1 Incomplete Did not participate
Martian Natural Selection
Natural selection is the survival of the fittest organism. Charles
Darwin observed four major points about natural selection: 1. more offspring are produced then can survive, 2. in any population, variation exists, 3. some variations are favorable, 4. those with favorable variations survive and reproduce. But what makes an organism most fit?
In this activity, you'll investigate natural selection and the pressures driving the potential changes in the population's gene pool.
Problem: What is natural selection?
Materials: penny, beans, tray, forceps, wood splints, straw, clothespin, paper plate
Part A. Genetic Drift
Background: In small populations that interbreed, such as certain religious groups, royal families and isolated populations, gene pools change quickly because the number of potential mates is limited.
Mistakes in meiosis (formation of male and female gametes) can result in genetic drift (a shift in the gene frequency w/in a population). In Part A, you will flip a coin to show how small populations can be affected by genetic drift and answer the questions.
Procedure: a. Flip a coin 100 times and record the number of heads and tails in the data table 1. The result will probably be close to 50-
50. b. Next, flip a coin 10 times and record the number of heads and tails in the data table 1.
Analysis:
1. If you flip a coin 100 times, are the chances likely or unlikely
100 flips
Heads
%
Table 1
Tails
%
10 flips
Heads
%
Tails that you'll get 100 heads and 0 tails? ____________. What about 80 heads and 20 tails?
_______________.
2. If you flip a coin 10 times, are your chances better or worse in getting 10 heads and 0 tails - or even 8 heads and 2 tails? _________________
3. Describe the genetic drift in terms of % change from 100 to 10 flips.
%
Part B Mutation
Background: It's happened. NASA has successfully landed on Mars. Twelve astronauts have established the first colony on the Red Planet. Or, at least that is what we thought. Much to the surprise of the astronauts, Mars was already inhabited! Martians run amuck in thousands of

underground tunnels unseen from Earth's telescopes. The astronauts learned a valuable lesson when they entered the first underground village. Apparently, the protein melanin, which is embedded in human skin and controls pigment, causes the Martian's green skin to mutate and turn purple on contact. So, every time the astronauts shook hands with a Martian, their skin proteins mutated and changed color!
Analysis:
4. Purple skin (S) is dominant to green skin (s). Predict the
probable genotypic and phenotypic ratios in the future generations within the mutated population of Martians.
Part C Natural Selection
Background: There have been three different species discovered on Mars, each living in their own population. These species all compete for the same food resource, a type of bean grown under the
Martian clay. Each species have different mouth parts that enable them to pick up beans to eat.
Some Martians have clothespin mouths, some have tweezer mouths, and some have chop-stick mouths.
Humans need to eat as well and have used their giant brains to devise an efficient manner of bean gathering - spoons!
Procedure: a. Martians only emerge for 30 second intervals to feed. Each Martian or human must collect 10 beans in order to survive and reproduce. Both are full after 15 beans and stop eating. Place the collected beans on the plate provided and start the trial. Each organism feeds separately. b. Record the collected number of beans in the table 2. Repeat for the next generations. c. Count the total beans taken by each organism and calculate an average.
Time
(Gen).
P
F1
F2
Total
Avg.
Trial 1
Beans collected
Tweezer clothespin Chopsticks
Human spoon
Table 2
Trial 2
Beans collected
Tweezer clothespin Chopsticks
Trial 3
Beans collected
Human Tweezer clothespin Chopsticks
Analysis:
5. What happens to animals that cannot compete as well with others in the wild?
6. 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?
7. Label the graph Directional, Disruptive, or Stabilizing Selection and circle which type of natural selection was on display in Part C.
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T
T
T
Human spoon