* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
Download 013368718X_CH17_267
Survey
Document related concepts
Hologenome theory of evolution wikipedia , lookup
Gene expression programming wikipedia , lookup
The Selfish Gene wikipedia , lookup
Sexual selection wikipedia , lookup
Saltation (biology) wikipedia , lookup
Mate choice wikipedia , lookup
Sociobiology wikipedia , lookup
Microbial cooperation wikipedia , lookup
The eclipse of Darwinism wikipedia , lookup
Genetics and the Origin of Species wikipedia , lookup
Natural selection wikipedia , lookup
Transcript
17.1 Genes and Variation Name: Biology Date: Period: Genetics Joins Evolutionary Theory Complete each statement by writing the correct word or words. 1. Natural selection works on an organism’s 2. A(n) rather than its . consists of all the genes, including the alleles for each gene, that are present in a population. 3. A gene pool typically contains different for each heritable trait. 4. The number of times that an allele occurs in a gene pool compared with the number of times other alleles for the same gene occur is called the of the population. Use the circle graph of a sample mouse population to answer the following questions. 5. In the diagram below, use circles to represent the alleles within each segment of the population. Draw the B alleles as solid circles and the b alleles as outline circles. a. The total number of individuals in this population is ; the total number of alleles is . b. How many alleles for black fur are in the sample population and what percentage of allele frequency does that represent? c. How many alleles for brown fur are in the sample population and what percentage of allele frequency does that represent? d. Describe how a geneticist might be able to tell that this population is evolving. 6. Can you determine whether an allele is dominant or recessive on the basis of the ratio of phenotypes in the population? Explain your answer. 1 Sources of Genetic Variation 7. What are mutations? When do they affect evolution? 8. How does sexual reproduction affect a population’s genetic variation? 9. Identify two ways in which genes can be recombined during meiosis. 10. Why is genetic variation important to the process of evolution? Single Gene and Polygenic Traits 11. Label the two graphs to show which represents a single-gene trait and which represents a polygenic trait. Write True if the statement is true. If the statement is false, change the underlined word or words to make the statement true. 12. The number of phenotypes produced for a given trait depends on how many genes control the trait. 13. Height in humans is an example of a single-gene trait. 14. Each gene of a polygenic trait often has two or more phenotypes. 15. A single polygenic trait often has many possible genotypes. 16. A symmetrical bell-shaped graph is typical of polygenic traits. 2 Use the Venn diagram to compare and contrast single-gene traits and polygenic traits. Single-Gene Traits Both Polygenic Traits Concept Map A concept map helps you see how the topics you read about are related to one another. Use the words and phrases below to fill in the empty spaces in the concept map. Genetic recombination Chromosomes Genes Crossing-over Sources of Genetic Variation include Lateral gene transfer Mutations involve changes in happens during Meiosis 3 Single-Gene and Polygenic Traits Polygenic Traits Some traits are controlled by only one gene. They are called single-gene traits. Other traits are controlled by two or more genes. They are called polygenic traits. Human height is an example of a polygenic trait. Height in cm 155–159 160–164 165–169 170–174 175–179 180–184 185-189 190–194 Number of Students 1 2 6 10 10 6 2 1 1. Draw a curve connecting the data points. 2. What shape is the curve you drew? a. bell curve b. one-sided curve 3. What is the average height for this population? a. 155–164 cm b. 165–174 cm c. irregular curve c. 170–179 cm d. 185–194 cm 17.2 Evolution as Genetic Change in Populations Term Definition A change in an allele’s frequency following a dramatic reduction in population size Form of natural selection in polygenic traits in which the entire curve shifts because some individuals are more successful at surviving Form of natural selection in polygenic traits in which the curve splits in two because individuals at the two ends are more successful at surviving than those in the center A change in an allele’s frequency that occurs as a result of a migration of a small part of the population A random change in an allele’s frequency When all of the alleles in a population remain the same The process of selecting a mate based on traits like strength or color Form of natural selection in polygenic traits in which the center of the curve stays in the same position because the individuals in the center are more successful at surviving 4 How Natural Selection Works 1. If a trait made an organism less likely to survive and reproduce, what would happen to the allele for that trait? 2. If a trait had no effect on an organism’s fitness, what would likely happen to the allele for that trait? Use the table showing the evolution of a population of mice to answer the following questions. Initial Population Generation 10 Generation 20 Generation 30 90% 80% 70% 40% 10% 20% 30% 60% 3. Is the trait for fur color a single-gene trait or a polygenic trait? Explain your answer. 4. Describe how the relative frequency of fur color alleles is changing in this population and propose one explanation for this change. 5. Suppose a mutation causes a white fur phenotype to emerge in the population. What might happen to the mouse population after 40 generations? 6. What effect does stabilizing selection have on variation in a population? 5 original population original population Number of Birds in Population Percentage of Human Population Natural Selection on Polygenic Traits In most populations, a trait that has higher fitness leads to greater numbers of organisms with that trait. The solid lines show the population after selection has taken place. Label the graphs as disruptive selection or stabilizing selection. Birth Weight __________________________ Beak Size __________________________ 7. With which type of selection do organisms in the middle of the curve have the highest fitness? 8. In disruptive selection, organisms on which part of the curve have the lowest fitness? 9. How does the curve change in stabilizing selection? The curve a. becomes shorter and wider. c. moves to the right. b. becomes taller and narrower. 10. The plants in an area have either very small or very large seeds. Birds with small beaks can eat small seeds, and birds with large beaks can eat large seeds. Birds with smaller beaks and birds with larger beaks become more common than birds with medium beaks. What type of selection is this? a. stabilizing selection b. disruptive selection c. directional selection Genetic Drift – Use what you know about the Hardy-Weinberg principle to identify what is happening. 11. Genetic drift strongly affects the population. a. small population b. random mating c. no movement into or out of the population d. no natural selection 12. Lions with a darker fur color have the same chance to reproduce as lions with a lighter fur color. a. large population c. no mutations b. random mating d. no natural selection 13. Fitness is basically the same among individuals in the population. a. large population c. no mutations b. random mating d. no natural selection 14. In small populations, random changes in is called genetic drift. 15. A situation in which allele frequencies change as a result of the migration of a small subgroup of a population is known as the 16. The . is a change in allele frequency following a dramatic reduction in the size of a population. 6 Complete the concept map. Genetic Drift can result from Bottleneck Effect caused by caused by Evolution Versus Genetic Equilibrium 17. What does the Hardy-Weinberg principle state? 18. What is genetic equilibrium? 19. Use phrases in the word box to identify each condition that leads to genetic equilibrium. large population random mating no natural selection no mutations no movement The Hardy-Weinberg Principle The more individuals in the population, the smaller the effect of genetic drift. No changes to genes means new alleles are not introduced into the population’s gene pool. Each individual in a population has the same chance of passing on its alleles. No new alleles are introduced into the population’s gene pool by new individuals. No phenotype can have a selective advantage over another—all individuals have equal fitness. 20. Explain how sexual selection results in non-random mating. 21. Suppose a population of insects live in a sandy habitat. Some of the insects have tan bodies and some have green bodies. Over time, the habitat changes to a grass-filled meadow. Use the ideas of natural selection to explain how and why the insect population might change. 7 17.3 The Process of Speciation Isolating Mechanisms 1. What is speciation? 2. What does it mean for two species to be reproductively isolated from each other? 3. What must happen in order for a new species to evolve? 4. Many finch characteristics appear in bell-shaped distributions typical of traits. 5. The ancestors of the Galápagos Island finches originally came from the continent of . 6. The populations of finches on separate islands are isolated from one another by large stretches of open water. Populations Become Isolated - Read the chart below. Then, use phrases in the word box to identify each process that leads to speciation. changes in the gene pool geographic isolation founders arrive competition behavioral isolation Process How It Leads to Speciation A population arrives in a new place. Populations are separated by a geographic barrier and do not share a gene pool. Populations evolve new traits in response to natural selection in their environments. Species evolve in a way that reduces competition between them. Groups within a population are separated by different courtship rituals. 8 Speciation in Darwin’s Finches - Charles Darwin proposed that the different species of finches on the Galapagos Islands once had a common ancestor. Over time, he said, natural selection led to each species of finch. A current hypothesis says that speciation in the Galapagos finches occurred through the founding of a new population, geographic isolation, changes in the new population’s gene pool, behavioral isolation, and ecological competition. Use the phrases in the box to complete the chart. insects that live inside dead wood fruits large, thick-shelled seeds small seeds Galápagos Islands Finches Shape of head and beak Main food Feeding adaptation Habitat fruits Parrot-like beak uses cactus spines pointed crushing beak large crushing beak trees trees ground ground 7. How does the large crushing beak help the fourth finch survive? 8. Circle the finch that would be least likely to survive if the insect population decreased. 9. Both the first and second finch live in trees. Suppose one season there is less fruit in the trees. Which finch is more likely to survive and reproduce? Populations Become Isolated Speciation occurs when a new species evolves. Many things contribute to speciation. Read the chart below and use phrases in the word box to identify each process that leads to speciation. changes in the gene pool geographic isolation founders arrive competition behavioral isolation Process How It Leads to Speciation A population arrives in a new place. Populations are separated by a geographic barrier and do not share a gene pool. Populations evolve new traits in response to natural selection in their environments. Species evolve in a way that reduces competition between them. Groups within a population are separated by different courtship rituals. 10. Finches prefer to find mates with the same size beaks. Finches in Group A have larger beaks than those in Group B, so finches from the two groups will not mate. What is this an example of? 9 11. Do populations that are geographically isolated from one another share a gene pool? Why or why not? 12. Complete the table with the correct terms. Term Definition The number of times an allele appears in a gene pool, compared to the total number of alleles in that pool for the same gene. A common group of genes, and all their alleles, shared by a population A trait controlled by two or more genes A trait controlled by only one gene A change in an allele’s frequency following a dramatic reduction in population size Form of natural selection in polygenic traits in which the entire curve shifts because some individuals are more successful at surviving Form of natural selection in polygenic traits in which the curve splits in two because individuals at the two ends are more successful at surviving than those in the center A change in an allele’s frequency that occurs as a result of a migration of a small part of the population A random change in an allele’s frequency When all of the alleles in a population remain the same The process of selecting a mate based on traits like strength or color Form of natural selection in polygenic traits in which the center of the curve stays in the same position because the individuals in the center are more successful at surviving When two populations have different behaviors that keep them from reproducing When two populations are separated by geographic features, such as rivers or mountains, that keep them from reproducing Separation of populations so that they cannot reproduce A population or group of populations whose members can interbreed and produce fertile offspring The forming of a new species When two populations reproduce at different times, so that they cannot reproduce together 10