Gizmos Evolution, Natural and Artificial Selection

Gizmos Evolution, Natural and Artificial Selection Student Exploration: Evolution: Natural and Artificial Selection ...

Gizmos Evolution, Natural and Artificial Selection Student Exploration: Evolution: Natural and Artificial Selection Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: artificial selection breed chromosome evolution fitness genotype mutation natural selection, phenotype [Note to teachers and students: This Gizmo was designed as a follow-up to the Evolution: Mutation and Selection Gizmo. We recommend doing that activity before trying this one.] Prior Knowledge Question (Do this BEFORE using the Gizmo.) This illustration from an old textbook shows some of the over 150 different dog breeds that can be seen around the world today. How do you think all of these different breeds were developed? Gizmo Warm-up Dog breeds and other varieties of domesticated animals were developed through artificial selection. Over many generations, breeders selected which animals to mate in order to select for desired traits. The Evolution: Natural and Artificial Selection Gizmo allows you to try your hand at breeding insects with a variety of colors. To begin, select the Artificial selection option. 1. Drag the 10 insects into the breeding alcoves on the left side of the Gizmo. A. How many breeding pairs are there? B. How many offspring are produced? 2. Circled insects have mutations, or changes to their DNA. How many of the offspring insects in this generation have mutations? Activity A: Genotype and phenotype Get the Gizmo ready: ● Select Natural selection. Question: How are genes inherited and modified over many generations? 1. Observe: The fitness of an insect is a measure of how well it is adapted to its environment. A. What is the initial Average fitness of these insects? B. Click Play ( ), and observe the simulation for several generations. What occurs in each generation? C. Increase the Sim. speed by one level. Click Pause ( ) after 30 generations. What is the Average fitness now? 2. Analyze: Set the Sim. speed to its slowest level. Click Play, and then Pause when the offspring appear. Choose a pair of parents in which both parents have a different color. A. Move your cursor over a parent insect. The genes that control color make up an insect’s genotype, while its actual color is its phenotype. Fill in the genotypes and phenotypes of each parent below. Parent 1 genotype Parent 1 phenotype Parent 2 genotype Parent 2 phenotype Red= Green= Blue = Red= Green= Blue = Now list the genotypes of each of the four offspring below. Offspring 1 Offspring 2 Offspring 3 Offspring 4 BWG BWG BWG RWG WRG CRW WRG RWG 3. Explain: Each rod-shaped structure is a chromosome. Real chromosomes contain hundreds or even thousands of genes. The simplified chromosomes shown in this Gizmo only contain genes that determine the insects’ colors. How are the chromosomes of the offspring related to the chromosomes of the parents? 4. Investigate: Any insect that has a mutation will be circled. Place your cursor on an insect with a mutation to examine its genotype. (If there are none in this generation, click Play and then Pause when a mutation appears.) A. Examine the genotype of the mutated insect as well as the genotypes of its parents to determine what the mutation is. What new gene appeared? B. Do you think this mutation is helpful, harmful, or neutral for the insect? Explain. C. Click Play, and then click Pause after the birds have finished eating. Did the mutated insect survive? 5. Observe: Increase the Sim. speed by two levels. Click Play, and wait for a while. What occurs as time goes by?