Download Natural Selection of Lepidopterans

Natural Selection of Lepidopterans
Objectives: To study a population that shows phenotypic and genotypic variation.
To see how natural selection can cause adaptive changes in the population.
To simulate adaptations that affect a predator’s ability to capture prey.
To observe how color affects an organism’s ability to survive in certain environments.
Georgia Performance Standards:


SB4f. Relate animal adaptations, including behaviors, to the ability to survive stressful environmental
conditions.
SB5d. Relate natural selection to changes in organisms (changes in a species’ population).
PreLab Questions (Background Information for your lab report. Remember to use complete sentences!):
1. What is meant by phenotype? What is meant by genotype?
2. Explain how natural selection is the driving force for evolution.
3. What traits or characteristics would make a bird a successful predator? What traits or characteristics would
enable a butterfly to successfully avoid becoming a bird’s prey?
4. Give an example of, or describe what a population would look like, with little or no genetic variation.
Under what conditions would this low genetic variability prove detrimental (harmful) to the population?
5. What is the advantage for a population that has several different phenotypes due to a relatively large genetic
variability among the members?
6. Formulate two separate hypotheses using the “If…then…because…” format. One hypothesis should predict
which hunting adaptation will be most successful for the birds. The second hypothesis should predict which
color of Yarn Butterfly will survive best in which habitat.
Background Information about this lab:
In this lab, students will study the effects of predator adaptations on a population of butterflies and the effects
of coloration on natural selection. Students will simulate three different habitats found on an island (volcanic rock, sandy
beach, and forest) using construction paper (black and white) and newspaper. Students will investigate one particular
species of Yarn Butterfly (prey) which shows at least 5 different phenotypes in wing color. In addition, students will
simulate a species of bird (predator) with 2 different hunting adaptations (spoon and fork).
Phenotypic variation is an important factor influencing natural selection. Darwin used the term natural selection
to indicate that nature (the environment) selects for traits in individuals and those traits which are best suited for the
environment enable the organism to survive and reproduce, thereby passing those ‘best suited traits’ on to the next
generation. In this way, the frequency of traits within a population can fluctuate over time because some organisms
have greater reproductive success than others.
Hypotheses: See #5 above
Materials: construction paper (black & white), newspaper, timer, plastic fork & spoon, yarn butterflies (10 each of 5
different colors)
Procedure:
1. Place all 50 yarn butterflies on your “background” construction paper.
2. Have a group member act as a bird that eats butterflies (the “predator”). Hold the plastic spoon in one hand
while sitting on the other hand, capture as many butterflies as possible within a 15 second time period.
Remember, the bird can only catch one butterfly at a time.
3. At the end of the 15 second time period, record the number of each of the different colored butterflies
captured.
4. Repeat steps 1-3 using black construction paper for the volcanic rock, white for the beach, and newspaper for
the forested area.
5. Repeat steps 1-4 using a plastic fork instead of the spoon.
Data Record data on the data tables provided
Data Analysis Determine which type of graph would display your data best and graph the data. Remember, you can use
the free Create-a-Graph tool: (http://nces.ed.gov/nceskids/createagraph/)
Conclusion (Answer these questions in the conclusion part of your lab report. Your answers should be supported by the
data you collected. Give detailed explanations!)
1. Which hunting adaptation made the birds successful predators? Does your data support your hypothesis? Why
or Why not?
2.
What could happen to the birds with the less successful adaptation? Explain your answer.
3. What traits (besides using the spoon or fork) could affect the hunting success of the student who was roleplaying the bird?
4. Which butterfly color provided the best protection on the volcanic rock? On the beach? In the forest setting?
Does your data support your hypothesis? Were you surprised by the outcome? Why or why not?
5. Why is genetic variation important for a real population?
6. If the volcano on the island undergoes a major eruption and 90% of the forest is destroyed, which color of Yarn
Butterfly will be most vulnerable to predation? Explain your answer.
7.
How does the scenario played out in this lab help your understanding of natural selection?
Data Tables
Phenotypic Varieties of Yarn Butterfly
Habitat
Record quantity of butterflies caught successfully with a spoon!
Sunshine Yellow
Rockin’ Red
Glamorous Green
Boisterous Beige
Seafoam Green
Volcanic Rock
Sandy Beach
Forest
Phenotypic Varieties of Yarn Butterfly
Habitat
Record quantity of butterflies caught successfully with a fork!
Sunshine Yellow
Volcanic Rock
Sandy Beach
Forest
Rockin’ Red
Glamorous Green
Boisterous Beige
Seafoam Green