SBI3U - Evolution
Evolution: Natural and Artificial Selection Lab
Evolution is probably one of the more difficult things to study in a biology lab, especially at the
high school level. For this reason, we will be doing a computer simulation instead. Just like a
regular lab, you will be required to collect data, but it will be from a digital source.
Log in to Explore Learning
http://www.explorelearning.com/index.cfm?method=cResource.dspDetail&ResourceID=575&Cl
assID=2096962
Before we start the gizmo…
Corn today looks tasty (especially roasted on the BBQ) but it
didn’t always look so great. On the right is a picture showing
the evolution of corn over the last ten thousand years.
Much of this development happened in Mexico where
remains of the different cobs of corn have been found.
How do you think the corn managed to go from its primitive state to
its current (delicious) state?
GIZMO TIME!
SBI3U - Evolution
For this gizmo, you will be mating bugs together or observing their mating.
Set the selection on the bottom of the left panel to Natural Selection
There are 10 bugs shown. When you run the simulation they will assort randomly into the
‘breeding alcoves’ on the left side and produce four offspring. The offspring produced by a couple
are on the same level as the parents. If a mutation arises, it will be circled.
Default Settings: R: 85 G: 255 B: 43
Mutation rate 1.0,
Sim speed Lowest setting.
Fitness
Fitness measures how well an organism is adapted to its environment.
1. What is the starting average fitness of bugs for the simulation?
2. What do you think will happen to the average fitness as time passes?
Set the simulation rate to the second slowest speed. Run the simulation. Pause the simulation
and record the fitness at the following number of generations
0 (1) 10
20
30
40
50
60
70
80
90
100
50%
Graph the fitness (or use excel and show your teacher)
What happened to the average fitness?
SBI3U - Evolution
What caused the average fitness to change?
Do you expect this trend to reach 100%? Why/why not?
Is there any reason why average fitness might go down?
Mutations
Let the simulation run until you get a mutation, then pause it.
What are the genotypes of the parents and the mutant? Fitness?
Genotype:
Parent 1:
Parent 2:
Offspring:
Fitness:
Is this mutation beneficial, harmful, or neutral? Turn the simulation speed to its lowest setting,
press play, then pause after the birds have finished eating. Did this bug get eaten by the birds?
If you had a beneficial mutation (one that increased the fitness of the organism), but it still got
eaten, how could you explain this? If you had a detrimental mutation and it survived, how is this
possible?
Does evolution occur at the level of the individual or the population?
Using all the knowledge you have just gathered, how do you think natural selection occurs?
SBI3U - Evolution
Artificial Selection
Set the Mutation Rate to 2.0. and the selector to Artificial Selection
Suppose you wanted to breed bugs of the ‘ideal colour’. What colour would it be? __________________
What is artificial selection?
How would you go about getting bugs of the ideal colour?
Follow the Gizmo instructions to produce insects of the desired colour. Drag mating pairs into
the alcoves in order to get your ideal colour. This may take a while.
How many generations did it take to achieve your ideal colour?___________________
What was the average fitness of the bugs? ____________
What do you think is the role of background colour on artificial selection? Do you NEED to have
your background colour be the desired colour for your bugs? Why/Why not?
Reset the simulation, Set the background colour to your desired colour, and select Natural
Selection.
Run the simulation until you get a 90% average fitness. How many generations did it take?
Repeat the experiment twice more to get the average number of generations
Trial
1
2
3
Average
# generations needed to
get 90% fitness
Do you think natural or artificial selection would occur faster? Explain.
Often farmers will breed the biggest plants together to get one homogenous ‘big’ lineage of
plants. Can you think of a disadvantage with having one primary breed of plants?
Play around. See if you can use artificial selection to generate two different, distinct colours!
SBI3U - Evolution
Mutation Rate
Now we will look at the affect of mutation rate on selection.
Set the sim speed to it’s lowest possible setting and the Mutation Rate to 0.1
Run the simulation for one trial and record the number of mutated insects. Repeat this
experiment twice more. Change the mutation rate to that listed in the table. Repeat the
experiment and calculate the average number of mutations acquired for each mutation rate.
Mutation Rate Trial 1
Trial 2
Trial 3
Average
Avg/40
0.1
1.0
5.0
10.0
Divide the average number of mutations by the number of offspring produced in each generation
(40). How does this compare to the mutation rate?
How do you believe the rate of mutation will affect the ability of the bug population to increase in
average fitness?
Reset the simulation and set the mutation rate to 0.1 Record how many generations it takes for
the population to reach 90% fitness at each of the following mutation rates. Repeat the
experiment in triplicate and record the average fitness.
Mutation Rate Trial 1
Trial 2
Trial 3
Average
0.1
0.5
1.0
2.0
4.0
7.0
10.0
Graph your results on the next page or in Excel. If it is too hard to graph the values less than 1.0,
ignore them.
How does mutation rate affect the speed at which a population adapts to its environment?
SBI3U - Evolution
Can having a high mutation rate be detrimental and cause a population to take longer to reach an
ideal fitness?
Certain parts of the human genome are more prone to mutation than others, that is to say that
there is a higher mutation rate. Describe one positive and one negative point about having a high
mutation rate.
Certain human cells are more prone to cancer than others. Breast tissue, colorectal tissue,
stomach tissue, uterine cells, skin, and certain other glands are very prone to developing
tumours. Muscles and nerves are much less susceptible to cancer. Skin cells are constantly being
replaced while nerves do not regenerate. Following this logic and what you know about
generation time, might you be more likely to get stomach cancer than muscle cancer?
FIN
SBI3U - Evolution
Evolution: Natural and Artificial Selection Lab
Teacher Resource
Ministry requirements:
This lab actually hits on all three Overall Expectations of the Evolution unit:
 c1. analyze the economic and environmental advantages and disadvantages of an artificial
selection technology, and evaluate the impact of environmental changes on natural
selection and endangered species;
 c2. Investigate evolutionary processes, and analyze scientific evidence that supports the
theory of evolution;
 c3. demonstrate an understanding of the theory of evolution, the evidence that supports
it, and some of the mechanisms by which it occurs.
Specific Expectations
 c2.1 use appropriate terminology related to evolution, including, but not limited to:
extinction, natural selection, phylogeny, speciation, niche, mutation, mimicry, adaptation,
and survival of the fittest [C]
 c2.2 use a research process to investigate some of the key factors that affect the
evolutionary process (e.g., genetic mutations, selective pressures, environmental
stresses) [IP, PR]
 c2.4 investigate, through a case study or computer simulation, the processes of natural
selection and artificial selection (e.g., selective breeding, antibiotic resistance in
microorganisms), and analyse the different mechanisms by which they occur [PR, AI, C]
 c3.4 describe some evolutionary mechanisms (e.g., natural selection, artificial selection,
sexual selection, genetic variation, genetic drift, biotechnology), and explain how they
affect the evolutionary development and extinction of various species (e.g., Darwin’s
finches, giraffes, pandas)
The Gizmo is an excellent resource for demonstrating evolution in the classroom. It can run
many generations over a very short amount of time and can factor in probabilities of mutation
and selection. There are other great resources on the ExploreLearning website.
Some limitations of this lab will be the procurement of computer lab time for students to
do the simulations and lab activities. Also, the teacher must have access to ExploreLearning.
Some students may not be particularly tech savvy and may have difficulty using the online
resource. Students with certain motor skill deficiencies may have difficulty using the program.
More advanced students can be given personal challenges such as ‘can you use artificial
selection to develop three unrelated groups of bugs?’ and can be offered bonus marks as an
incentive.
Weaker students may find some of the investigative parts of the lab difficult, but on the
whole, the lab lends itself to slowly coaxing students along the path of discovery so that they
learn about different facts as they prove them and experience them.
Do not feel the need to chastise students for playing around with the software and not
following the lab. Assure them that they must complete the lab (likely for completion marks), but
encourage play as it generates interest, excitement, and learning. Turn playtime into
personalized challenges (what are the ideal conditions to get ______? How many generations to
get ____?).