• Assess students’ understanding of natural selection during the warm-up discussion of survival of the fittest on Day 1 and review concepts from the previous lesson as needed.
• Circulate around the room as students work on sequencing maps, correcting any misunderstandings and asking comprehension questions. Collect and check students’ sequencing maps on speciation.
• Orally assess students’ understanding of the formation of new species during the follow-up discussion after the Speciation Demonstration.
• Collect and check students’ creative writing to assess their understanding of natural selection and speciation.

Note: This lesson requires prior knowledge of genotypes and alleles.

Day 1

Begin the lesson with a writing prompt: “Explain the concept of survival of the fittest in your own words. How does it relate to the lab activity from the previous lesson?” Allow several minutes for students to write their answers, then have several students share their responses with the class.

Present a mini-lesson on factors that can lead to speciation (S-B-9-2_Speciation-Teacher Version.doc). Have students take notes on the definitions of gene pool, speciation, genetic drift, founder effect, behavioral isolation, and geographic isolation.

If computers with Internet access are available, have students view the Random Sampling and Genetic Drift animation (see Related Resources).

Read the following scenario to students: “A flood washes a few lizards to an ocean and they drift to an island. How could this lead to speciation in the lizard populations?” Have students work alone or in pairs to create a sequencing map to show the process by which geographic isolation could lead to speciation in this scenario (S-B-9-2_Sequencing Map-Teacher Version.doc).

Day 2

Begin the lesson with a demonstration of speciation via geographic isolation (S-B-9-2_Speciation Demonstration-Teacher Version.doc).

Follow the demonstration with a creative writing activity. Introduce the activity by reading the following scenario to students, to represent natural selection and geographic isolation:

A small group of humans migrates to Planet X, without any books, weapons, or technology. Planet X has no ozone layer to protect its surface from cancer-causing radiation from the Sun, but native plants and animals have evolved to survive there. There is a network of underground tunnels that are inhabited by carnivorous predators. Predict how the descendants of this group of humans will look and act after 100,000 years on Planet X.

Allow 5–10 minutes for students to brainstorm with a partner, and then have students write their predictions, including an explanation of natural selection and geographic isolation.

Extension:

• For students who may need opportunities for additional learning, provide a template for the sequencing map to complete. Review the founder effect by having them sequence the following steps: founders arrive, founders remain geographically isolated, natural selection occurs in different environments, reproductive isolation produces two new species. Note: The steps are in order here; you may choose to present them out-of-order for student practice.
• For the creative writing activity, give students who may need opportunities for additional learning a choice for the format of their response, such as paragraphs, sequencing map, or diagrams.
• Students who might be going beyond the standards can research the Hardy-Weinberg principle and make a list of the conditions required to maintain genetic equilibrium (i.e., random mating, large population, no migration, no mutations, and no natural selection.) Have them explain how the Hardy-Weinberg principle relates to the speciation demonstration from Day 2 of this lesson.