Evidence for evolution comes from fossils and comparisons of the anatomy, embryos, and DNA of living things. Further evidence comes from biogeography, or the study of how and why organisms live where they do. Adaptive radiation occurs when one species evolves into many new species to fill available niches.
- CA.9–12.IE.1.d, I; CA.9–12.LS.8.a, e, f
- AAAS.9–12.5.A.2; AAAS.9–12.F.2.9
- Describe how fossils help us understand the past.
- Explain how evidence from living species gives clues about evolution.
- State how biogeography relates to evolutionary change.
adaptive radiation: process by which a single species evolves into many new species to fill available niches
analogous structure: structure that is similar in unrelated organisms because it evolved to do the same job, not because it was inherited from a common ancestor
biogeography: study of how and why plants and animals live where they do
comparative anatomy: study of the similarities and differences in the structures of different species
comparative embryology: study of the similarities and differences in the embryos of different species
homologous structure: structure that is similar in related organisms because it was inherited from a common ancestor
paleontologist: scientist who finds and studies fossils to learn about evolution and understand the past
vestigial structure: structure such as the human tailbone or appendix that evolution has reduced in size because it is no longer used
Introducing the Lesson
Pass a fossil, fossil reproduction, or photo of a fossil around the classroom (you can order fossils at the URL below). Ask students what they can infer about the organism from its fossil (e.g., living in water for a shell fossil). Tell students they will read in this lesson how scientists use fossils to determine what extinct organisms were like and how they evolved.
Have students compare and contrast the homologous and analogous structures figures (see FlexBook® textbook, Figure 10.8 and Figure 10.9). Challenge students to explain how each figure provides evidence for evolution (i.e., descent from a common ancestor (homologous structures) and evolution of similar adaptations in unrelated organisms (analogous structures).
Have pairs or small groups of students make Frayer models for the vocabulary words “homology” and “analogy.” To make a Frayer model, they should divide a sheet of paper into four squares labeled “Definition,” “Example,” “Drawing,” and “Non-example.” They should work together to fill in the squares. ELL, LPR
Ask a few students to find and compare amino acid sequences in the protein cytochrome c. They should try to find data for at least three different species. The URL below is a good starting point. Students should use the data to infer which species are more closely related (those with the more similar sequences). Ask students to present their work to the class and explain why cytochrome c is especially useful for reconstructing phylogenetic relationships.
Assign the activity at the URL below. Using real data, students will develop phylogenies for related populations of lizards on the Canary Islands. They will use several different types of data, including biogeography, morphology, and DNA data.
A common misconception is that there is little or no evidence for evolution. In fact, there is a huge amount of evidence for evolution and it comes from a diversity of fields. The URL below provides a summary and many examples. You can share it with your students.
Reinforce and Review
Copy and distribute the lesson worksheets in the CK-12 Biology Workbook. Ask students to complete the worksheets alone or in pairs as a review of lesson content.
Have students answer the Review Questions listed at the end of the lesson in the FlexBook®.
Points to Consider
The Grants saw evolution occurring from one generation to the next in a population of finches.
- What factors caused the short-term evolution the Grants witnessed? How did the Grants know that evolution had occurred?
- What other factors do you think might cause evolution to occur so quickly within a population?