In this activity, students formulate a hypothesis and collect and analyze real research data about how quickly natural selection can act on specific traits in a population as a result of predation. It is accompanied by a short video that describes the experiment this activity is based on.

Using measurements from a year-long field study on predation in which Dr. Jonathan Losos and colleagues introduced a large predator lizard to small islands that were inhabited by Anolis sagrei, this activity illustrates the role of predation as an agent of natural selection. It emphasizes that strong selective pressure can have measurable effects on trait variations in a population within a short time. After watching the short film The Origin of Species: Lizards in an Evolutionary Tree, students use a sample of research data from actual field experiments to work through this four-part activity:

• Part 1: Introduction of the field study and formulate a hypothesis.
• Part 2: State the hypothesis formulated by Losos and colleagues and how they tested it.
• Part 3: Collect data, perform simple calculations, and answer questions.
• Part 4: Watch a video on additional findings and answer discussion questions.

The quantitative analysis includes calculating and interpreting simple descriptive statistics and plotting the results as line graphs. The flow of this four-part activity is illustrated in Figure 1 on page 3 of the educator materials.

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