EVIDENCE FOR EVOLUTION

Key Concept

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.

Standards

• CA.9–12.IE.1.d, I; CA.9–12.LS.8.a, e, f

• NSES.9–12.C.3.3

• AAAS.9–12.5.A.2; AAAS.9–12.F.2.9

Lesson Objectives

• 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.

Lesson Vocabulary

• 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

10.2. EVIDENCE FOR EVOLUTION

Teaching Strategies

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.

• http://www.teacherstorehouse.com/product_search.asp?order_key=#38;track=#38;submit=TRACK#38;term=fos sil

Use Visuals

Have students compare and contrast the homologous and analogous structures figures (see FlexBook, 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).

Differentiated Instruction

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

Enrichment

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.

• http://chemistry.umeche.maine.edu/CHY431/Evolve2.html

Science Inquiry

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.

• http://www.indiana.edu/ ensiweb/lessons/island.html

Overcoming Misconceptions

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.

CHAPTER 10. TE THE THEORY OF EVOLUTION

• http://www.talkorigins.org/indexcc/CA/CA202.html

Reinforce and Review

Lesson Worksheets

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.

Review Questions

Have students answer the Review Questions that are listed at the end of the lesson in their FlexBook.

• Sample answers to these questions will be provided upon request. Please send an email to [email protected] to request sample answers.

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?

– (A drought and lack of food caused the birds to evolve. Their average beak size increased over 2 years.)

• What other factors do you think might cause evolution to occur so quickly within a population?

– (Accept all reasonable responses. Sample answer: a natural disaster)

10.2. EVIDENCE FOR EVOLUTION

10.3 Microevolution and the Genetics of Populations

Key Concept

The population is the unit of evolution. All the genes of its members make up its gene pool, which is characterized by the frequency of alleles. The Hardy-Weinberg theorem states that, if a population meets certain conditions, its allele frequencies will not change. From the Hardy-Weinberg theorem, the forces of evolution can be inferred. The forces are mutation, gene flow, genetic drift, and natural selection.

Standards

• CA.9–12.IE.1.l; CA.9–12.LS.6.g; CA.9–12.LS.7.a, b, c, e, f; CA.9–12.LS.8.a, c

• NSES.9–12.A.2.4; NSES.9–12.C.2.3; NSES.9–12.E.2.1

• AAAS.9–12.1.C.4; AAAS.9–12.5.A.1; AAAS.9–12.5.B.1, 5; AAAS.9–12.5.F.3, 5, 6, 7, 9; AAAS.9–12.10.H.5;

AAAS.9–12.11.B.1

• McREL.9–12.13.5.6

Lesson Objectives

• Distinguish between microevolution and macroevolution.

• Define gene pool, and explain how to calculate allele frequencies.

• State the Hardy-Weinberg theorem.

• Identify the four forces of evolution.

Lesson Vocabulary

• allele frequency: how often an allele occurs in a gene pool relative to the other alleles for that gene

• directional selection: type of natural selection for a polygenic trait in which one of two extreme phenotypes is selected for, resulting in a shift of the phenotypic distribution toward that extreme

• disruptive selection: type of natural selection for a polygenic trait in which phenotypes in the middle of the phenotypic distribution are selected against, resulting in two overlapping phenotypes, one at each end of the distribution

• gene flow: change in allele frequencies that occurs when individuals move into or out of a population

• gene pool: all the genes of all the members of a population

• genetic drift: a random change in allele frequencies that occurs in a small population

• Hardy-Weinberg theorem: founding principle of population genetics that proves allele and genotype fre-quencies do not change in a population that meets the conditions of no mutation, no migration, large population CHAPTER 10. TE THE THEORY OF EVOLUTION

size, random mating, and no natural selection

• macroevolution: evolutionary change that occurs over geologic time above the level of the species

• microevolution: evolutionary change that occurs over a relatively short period of time within a population or species

• population genetics: science focusing on evolution within populations that is the area of overlap between evolutionary theory and Mendelian genetics

• sexual dimorphism: differences between the phenotypes of males and females of the same species

• stabilizing selection: type of natural selection for a polygenic trait in which phenotypes at both extremes of the phenotypic distribution are selected against, resulting in a narrowing of the range of phenotypic variation

Teaching Strategies

Introducing the Lesson

Review how probability can be used to predict the genotypes of offspring of two parents by applying Mendel’s rules of inheritance. Then say that probability can also be used to predict the genotypes in the next generation of a population. Tell students they will learn how when they read this lesson.

Building Science Skills

The Hardy-Weinberg theorem is often difficult for students to understand. Solving the Hardy-Weinberg practice problems at the URL below may improve student understanding.

• http://www.talkorigins.org/indexcc/CA/CA202.html

Differentiated Instruction

Create a gallery walk of the four forces of evolution (mutation, gene flow, genetic drift, and natural selection). Write the name of each force on a separate sheet of paper, and post one sheet on each wall of the classroom. Have groups of students circulate around the room, adding what they know to each sheet of paper and reading the comments of the other groups.

Enrichment

Challenge students who excel in math to solve more advanced Hardy-Weinberg problems. Suitable problems can be found at the URL below.

• http://mansfield.osu.edu/ sabedon/biol1509.htm

Science Inquiry

Students can explore natural selection with a virtual simulation at this URL.

• http://www.biologyinmotion.com/evol/index.html

In document CK 12 Biology Teacher's Edition (Page 148-152)