Crop Evolution and Selection: The Future of Farming

Name: ___________ Date: _______ Class: _________

Background Context

By the year 2050, the global human population is expected to reach nearly 10 billion. To feed this growing population, global food production will need to increase significantly. However, farmers are facing major challenges: a changing climate is altering growing conditions, and new strains of agricultural pests are devastating crops. You are an agricultural scientist tasked with developing a new strain of wheat that can produce high yields while resisting a newly emerged, highly destructive pest.

You will use a computational simulation to investigate three different methods of crop development: Natural Selection, Artificial Selection (Selective Breeding), and CRISPR Genetic Modification. Your goal is to determine the most effective strategy for adapting the crop population to survive the pest outbreak and maintain food security.

NGSS Alignment

• Performance Expectation: HS-LS4-4. Construct an explanation based on evidence for how natural selection leads to adaptation of populations.
• Science and Engineering Practice (SEP): Constructing Explanations and Designing Solutions; Analyzing and Interpreting Data
• Disciplinary Core Idea (DCI): LS4.C: Adaptation; LS4.B: Natural Selection
• Crosscutting Concept (CCC): Cause and Effect

Part 1: Baseline Data - Natural Selection

First, let’s observe how the crop population responds to the pest without human intervention.

1. Open the Crop Evolution and Selection Simulation.
2. Set the Selection Mode to “Natural Selection”.
3. Set Pest Pressure to 50.
4. Click Auto Play and allow the simulation to run for 10 generations. Pause the simulation.

Analysis Questions:

1. Analyze Data: Look at the “Population Trait Averages Over Time” graph. Describe the trend for Crop Yield and Pest Resistance over the 10 generations. Provide specific data points from Generation 0 and Generation 10.
2. Cause and Effect: Based on the rules of natural selection, explain why the average pest resistance changed the way it did. What was the selective pressure, and how did genetic variation in the initial population contribute to this outcome?
3. Construct an Explanation: Why did the average crop yield decrease even though pest resistance increased? (Hint: Consider the biological cost of producing defensive chemicals/structures).

Part 2: Artificial Selection (Selective Breeding)

Farmers have used artificial selection for thousands of years to improve crops. Let’s see if you can guide the population to a better outcome.

1. Click Reset Field.
2. Change the Selection Mode to “Artificial Selection”.
3. Keep Pest Pressure at 50.
4. Run the simulation for 10 generations, but this time, you must actively select the best plants (the ones with the highest yield and resistance) to be the parents of the next generation.
   • Note: You can click ‘Next Generation’ manually to observe the selection process step-by-step.

Analysis Questions:

1. Compare Outcomes: Compare the Generation 10 trait averages from your Artificial Selection trial to the Natural Selection trial. Was Artificial Selection more effective at maintaining high crop yield while increasing pest resistance? Use data to support your answer.
2. Mechanism: How does the mechanism of artificial selection differ from natural selection? Who or what is determining which individuals survive and reproduce in each scenario?
3. Limitations: Did you notice a limit to how fast the traits could improve using Artificial Selection? Explain why selective breeding is constrained by the existing genetic variation in the population.

Part 3: CRISPR Genetic Modification

Modern biotechnology allows scientists to directly edit the DNA of organisms using tools like CRISPR-Cas9.

1. Click Reset Field.
2. Change the Selection Mode to “CRISPR Genetic Modification”.
3. Keep Pest Pressure at 50.
4. In the CRISPR controls, set the Target Yield to 90 and the Target Resistance to 90.
5. Click Apply CRISPR Edits.
6. Run the simulation for 10 generations.

Analysis Questions:

1. Analyze Data: How did the population’s trait averages change immediately after applying CRISPR (Generation 1)? How did the traits change over the subsequent 9 generations?
2. Cause and Effect: Explain how CRISPR allows scientists to bypass the constraints of natural and artificial selection. Why is the change in traits almost instantaneous compared to the other methods?
3. Evolutionary Impact: Consider the genetic diversity of the population after CRISPR editing compared to Natural Selection. If a different type of pest suddenly arrived in Generation 11, which population (Natural Selection or CRISPR) do you think would have a better chance of containing individuals that might survive? Explain your reasoning based on the concept of genetic variation.

Part 4: Final Recommendation & Synthesis

1. Construct an Argument: Based on your simulation data, construct a final recommendation for the global agricultural council. Which method (Natural Selection, Artificial Selection, or CRISPR) should be prioritized to develop crops capable of feeding the future population amidst rising pest threats?
   • Your argument must include a claim.
   • You must provide evidence from your simulation trials (specific data points).
   • You must provide reasoning that connects your evidence to the biological concepts of natural selection, adaptation, and genetic variation. Discuss the trade-offs (benefits and risks) of your chosen method.