Beaks As Tools: Selective Advantage in Changing Environments
In this activity, students collect and analyze data from a hands-on model to discover why even slight variations in beak size can impact a bird’s ability to obtain food and survive.
in the 1970s and 1980s, medium ground finch populations in the Galápagos Islands experienced two major droughts. This activity simulates the food availability during these droughts and demonstrates how rapidly natural selection can act when the environment changes. In the model for this activity, students test which of two tools, which simulate different beak sizes, is better adapted to collect and “eat” seeds under various conditions. Students also watch clips from the short film The Beak of the Finch to provide context for what they will be modeling.
The accompanying “Group Data Table” handout is for student groups to record their data. The optional “Class Data Table” spreadsheet can be used to compile data from multiple groups for plotting graphs and calculating descriptive statistics (mean and standard deviation).
Student Learning Targets
- Explain how even slight variations in traits can impact an organism’s ability to survive.
- Use evidence to explain how environmental change can lead to strong selective pressure on certain traits.
- Develop an explanation about how traits can provide a selective advantage under different environmental conditions.
- Make predictions based on observations and collect quantitative data to test these predictions.
- Organize and analyze results by using computational thinking to make sense of data.
- Collect, analyze, and interpret data to identify patterns and possible cause-and-effect relationships.
adaptation, claim, fitness, Daphne Major, evidence, Galápagos, medium ground finch, reasoning, selective pressure, variation
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HS-LS2-1, HS-LS2-2, HS-LS4-2, HS-LS4-4, HS-LS4-5; SEP4, SEP6
EVO-1.D, EVO-1.E, EVO-1.J, SYI-3.D, EVO-1.M, EVO-1.O, EVO-3.A; SP1, SP5
Topic(s): 2.5, 2.6
Learning Objectives & Practices: ERT-2.G, ERT-2.H, SP1, SP2, SP4, SP5, SP6
Math.S-ID.3, S-IC.3; MP2, MP4
CC1, CC5; DP1