Transcript Answer key for natural selection simulation

Natural Selection Simulation
Learning objectives
Students are expected to be proficient with either Microsoft PowerPoint or Google
Docs Presentation tool prior to instruction.
Following instruction, the student will use Microsoft PowerPoint or Google Docs to…
1. Create a theoretical population of an organism.
1a. Define “population.”
1b. Define “organism.”
2. Propose a situation in which natural selection would occur.
2a. Recall the definition of natural selection.
2b. Define “selective force.”
2c. Provide an example of a selective force.
3. Illustrate how a selective force shapes a population.
3a. Describe how a selective force shapes a population.
4. Assess if evolution has occurred in a population.
4a. Explain why and how a population changed between generations.
In this assignment, you will create a theoretical situation in which natural selection occurs.
First, define population: A group of organisms of the same species in the same time and location.
Define organism: One living individual.
Define genetic variation: Differences in appearance and structure among individuals in a population.
Then, open shape tool. Each shape represents one organism. Insert shapes to make a population of organisms
with genetic variability in the space below. The space is the organisms’ habitat.
Make a population of 20 organisms out of shapes here.
Copy the population to slide 3.
Define selective force: a factor that influences changes in the genetic structure of future generations.
Define competition: a struggle between two organisms that decreases the survival or reproductive success of both
Define limited resource: a nutrient or other requirement that not all individuals can have.
Define predation: one organisms consumes another for food.
What selective force is acting on your population (you get to choose)? A predator can see green individuals better
than red or blue individuals.
How will this theoretical selective force affect your population? Fewer green individuals will survive and reproduce
than red or blue individuals.
This slide represents the first generation of the same population at a later time. Consider the selective force you
selected, and in the box below, indicate how the population has changed by omitting some the organisms (shapes).
This is the first generation after the selective pressure has eliminated some individuals
Paste the population from slide 2, then make deletions based on the selective force you chose.
Then copy this population to slide 4.
This slide represents the second generation of the same population. Assume that most of the individuals in slide 3
successfully reproduce. In the box below, indicate how the population looks after a reproductive bout.
This is the first generation after the selective pressure has eliminated some individuals
Paste the population from slide 2, then make deletions based on the selective force you chose.
Then copy this population to slide 4.
Answer the questions on the next two slides.
Do the two generations of your population depict natural selection? Yes. The genetic structure of the population
has changed.
Define natural selection: differential reproductive success of individuals with particular phenotypes
Define evolution: changes in allele frequencies in populations over time.
Why does the population on slide 4 (generation 2) differ from the population on slide 2 (generation 1)?
Because the selective force acting on generation 1 (predation of green individuals) eliminated some individuals
before they could reproduce. In other words, natural selection favored red and blue individuals over green
individuals.
How might you expect the population to change in subsequent generations?
If the selective force remains the same, then fewer green individuals will be present in future generations.
How might generation 2 have looked if individuals were eliminated at random rather than by some selective
force? (You can either create an example below using shapes or describe with words.)
Think of an actual species, or look one up online. Post a picture of a population of the species below.
What variation do you see in the population? What adaptations do all individuals have? What
selective forces may shape those adaptations? What selective force, if it arose, might eliminate some
of the variation in the population?
Answers will vary. Make sure that students are using what they see to make inferences about what
they know about natural selection.