Estimated Time: 45 minutes Materials: Computer or tablet, Natural Selection and Adaptation simulation, scratch paper or spreadsheet for data collection.
1. Engage
Anchoring Phenomenon: A population of organisms living in varying climates exhibits significant changes in average fur thickness over generations, and these changes accelerate when predators are introduced.
Discussion Questions:
- Why might organisms with different fur thicknesses survive better in some environments compared to others?
- What role might predators play in changing the makeup of the population over time?
- How can we use data to support an explanation of how these changes happen?
2. Explore
Simulation Instructions:
- Open the Natural Selection & Adaptation simulation.
- Note that the Climate slider controls the temperature (ranging from Cold -20°C to Hot 40°C).
- The “Enable Wolves” switch controls whether predators are present.
- The simulation shows organisms with varying fur thickness. Observe how the environment changes when you adjust the Climate slider and what happens to organisms.
- Create a data table to record the frequency of thick fur organisms over several generations under two conditions:
- Condition A: Cold Climate (10°C), no wolves.
- Condition B: Cold Climate (-20°C), with wolves enabled.
Sample Data Table:
| Generation | Thick Fur Frequency (Condition A) | Thick Fur Frequency (Condition B) |
|---|---|---|
| 100 | ||
| 500 | ||
| 1000 |
3. Explain
Using the data you collected from the simulation, construct an explanation for how natural selection leads to adaptation in the population. Your explanation should include:
- How the abiotic factor (climate) affected the survival and reproduction of organisms with varying fur thicknesses.
- How the biotic factor (wolves) contributed to a change in the frequency of the thick fur trait over time.
- Evidence from your data table that shows the change in trait frequency over multiple generations.
4. Elaborate/Evaluate
Extension Question: Imagine a sudden, permanent shift in the climate to extreme heat (40°C), while predators remain present. Based on your understanding of natural selection from the simulation, predict what will happen to the frequency of organisms with thick fur. Provide reasoning for your prediction using the concept of competitive advantage.
Teacher Notes
This task aligns with HS-LS4-4: Construct an explanation based on evidence for how natural selection leads to adaptation of populations.
Three-Dimensional Alignment
- Science and Engineering Practice (SEP): Constructing Explanations and Designing Solutions
- Students use data from the simulation as evidence to construct an explanation of how specific biotic and abiotic factors drive changes in gene frequency.
- Disciplinary Core Idea (DCI): LS4.C Adaptation
- Students explore how differential survival and reproduction lead to a population dominated by organisms with advantageous traits (e.g., appropriate fur thickness for the climate and predator presence).
- Crosscutting Concept (CCC): Cause and Effect
- Students distinguish between the cause (temperature changes and predators) and the effect (changes in the frequency of fur traits over time).
Evidence Statements Addressed
- Articulating the explanation of phenomena: Students construct an explanation that identifies the cause and effect relationship between natural selection and adaptation.
- Evidence: Students identify and describe evidence to construct their explanation, including changes in a population when some feature of the environment changes, and relative survival rates of organisms with different traits in a specific environment.
- Reasoning: Students use reasoning to synthesize valid and reliable evidence to construct the explanation, including that biotic and abiotic differences in ecosystems contribute to changes in gene frequency over time through natural selection. Over time, this process leads to a population that is adapted to a particular environment by the widespread expression of a trait that confers a competitive advantage.