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CAMPBELL BIOLOGY TENTH EDITION Reece • Urry • Cain • Wasserman • Minorsky • Jackson 23 The Evolution of Populations Clicker Questions by Bryan Jennings © 2014 Pearson Education, Inc. In evolutionary terms, an organism's fitness is measured by its ________. a) stability in the face of environmental change b) contribution to the gene pool of the next generation c) genetic variability d) mutation rate e) health © 2014 Pearson Education, Inc. In evolutionary terms, an organism's fitness is measured by its ________. a) stability in the face of environmental change b) contribution to the gene pool of the next generation c) genetic variability d) mutation rate e) health © 2014 Pearson Education, Inc. Red short-horned cattle are homozygous for the red allele, white cattle are homozygous for the white allele, and roan cattle are heterozygotes. Population A consists of 36% red, 16% white, and 48% roan cattle. What are the allele frequencies? a) red 0.36, white 0.16 b) red 0.6, white 0.4 c) red 0.5, white 0.5 d) Allele frequencies cannot be determined unless the population is in equilibrium. © 2014 Pearson Education, Inc. Red short-horned cattle are homozygous for the red allele, white cattle are homozygous for the white allele, and roan cattle are heterozygotes. Population A consists of 36% red, 16% white, and 48% roan cattle. What are the allele frequencies? a) red 0.36, white 0.16 b) red 0.6, white 0.4 c) red 0.5, white 0.5 d) Allele frequencies cannot be determined unless the population is in equilibrium. © 2014 Pearson Education, Inc. Indicate which of the Hardy-Weinberg conditions is being violated in this example: Some moths on a tree are easier to see due to their lighter color and therefore are eaten by predators more often. a) large population size b) no mutation c) no gene flow d) random mating occurring e) no selection © 2014 Pearson Education, Inc. Indicate which of the Hardy-Weinberg conditions is being violated in this example: Some moths on a tree are easier to see due to their lighter color and therefore are eaten by predators more often. a) large population size b) no mutation c) no gene flow d) random mating occurring e) no selection © 2014 Pearson Education, Inc. Indicate which of the Hardy-Weinberg conditions is being violated in this example: Male elephant seals show aggression toward other males, resulting in dominant males mating with several females and other males mating with few or no females. a) large population size b) no mutation c) no gene flow d) random mating occurring e) no selection © 2014 Pearson Education, Inc. Indicate which of the Hardy-Weinberg conditions is being violated in this example: Male elephant seals show aggression toward other males, resulting in dominant males mating with several females and other males mating with few or no females. a) large population size b) no mutation c) no gene flow d) random mating occurring e) no selection © 2014 Pearson Education, Inc. Indicate which of the Hardy-Weinberg conditions is being violated in this example: Due to global warming, a river has dried up, allowing two different rabbit populations to mate with one another, whereas they were isolated before. a) large population size b) no mutation c) no gene flow d) random mating occurring e) no selection © 2014 Pearson Education, Inc. Indicate which of the Hardy-Weinberg conditions is being violated in this example: Due to global warming, a river has dried up, allowing two different rabbit populations to mate with one another, whereas they were isolated before. a) large population size b) no mutation c) no gene flow d) random mating occurring e) no selection © 2014 Pearson Education, Inc. The textbook discusses how the conversion of quality habitat into farmland has greatly depleted the greater prairie chicken populations and, as a result, their genetic diversity. Which of the following occurred in this example? a) founder effects b) mutation c) natural selection d) gene flow e) bottlenecking © 2014 Pearson Education, Inc. The textbook discusses how the conversion of quality habitat into farmland has greatly depleted the greater prairie chicken populations and, as a result, their genetic diversity. Which of the following occurred in this example? a) founder effects b) mutation c) natural selection d) gene flow e) bottlenecking © 2014 Pearson Education, Inc. Indicate what type of selection is occurring in the example here: Due to less snowfall in an area, white mice are predated on more than intermediate- or darkcolored mice. a) directional selection b) disruptive selection c) stabilizing selection © 2014 Pearson Education, Inc. Indicate what type of selection is occurring in the example here: Due to less snowfall in an area, white mice are predated on more than intermediate- or darkcolored mice. a) directional selection b) disruptive selection c) stabilizing selection © 2014 Pearson Education, Inc. Indicate what type of selection is occurring in the example here: During a drought, it was discovered that finches with large beaks and those with small beaks were more successful due to the food sources available during the drought. a) directional selection b) disruptive selection c) stabilizing selection © 2014 Pearson Education, Inc. Indicate what type of selection is occurring in the example here: During a drought, it was discovered that finches with large beaks and those with small beaks were more successful due to the food sources available during the drought. a) directional selection b) disruptive selection c) stabilizing selection © 2014 Pearson Education, Inc. The frequency of cystic fibrosis, a recessive genetic disease, is 1 per 2,500 births among Northern Europeans. Assuming random mating, what is the frequency of carriers? a) 1/2,500, or about 0.04% b) 1/50, or about 2% c) 1/25, or about 4% d) The frequency cannot be calculated because selection violates Hardy-Weinberg assumptions. © 2014 Pearson Education, Inc. The frequency of cystic fibrosis, a recessive genetic disease, is 1 per 2,500 births among Northern Europeans. Assuming random mating, what is the frequency of carriers? a) 1/2,500, or about 0.04% b) 1/50, or about 2% c) 1/25, or about 4% d) The frequency cannot be calculated because selection violates Hardy-Weinberg assumptions. © 2014 Pearson Education, Inc. Until the 1950s, infants born with cystic fibrosis did not survive longer than a few months. If the frequency of carriers was 4% in the year 1900, what proportion of CF alleles was eliminated in one generation? a) 100% b) 50% c) 4% d) 2% e) 0.1% © 2014 Pearson Education, Inc. Until the 1950s, infants born with cystic fibrosis did not survive longer than a few months. If the frequency of carriers was 4% in the year 1900, what proportion of CF alleles was eliminated in one generation? a) 100% b) 50% c) 4% d) 2% e) 0.1% © 2014 Pearson Education, Inc. Which of the following evolutionary mechanisms increases the amount of genetic variation in a population? a) genetic drift b) mutation c) sexual selection d) directional natural selection e) stabilizing natural selection © 2014 Pearson Education, Inc. Which of the following evolutionary mechanisms increases the amount of genetic variation in a population? a) genetic drift b) mutation c) sexual selection d) directional natural selection e) stabilizing natural selection © 2014 Pearson Education, Inc. A high proportion of the cats on Key West have extra toes (polydactyly). What is the most likely explanation? a) high rate of mutation b) founder effect c) bottleneck effect d) directional selection for extra toes © 2014 Pearson Education, Inc. A high proportion of the cats on Key West have extra toes (polydactyly). What is the most likely explanation? a) high rate of mutation b) founder effect c) bottleneck effect d) directional selection for extra toes © 2014 Pearson Education, Inc. Scientific Skills Questions One way to test whether evolution is occurring in a population is to compare the observed genotype frequencies at a locus with those expected for a nonevolving population based on the Hardy-Weinberg equation. In this exercise, you’ll test whether a soybean population is evolving at a locus with two alleles, CG and CY , that affect chlorophyll production and hence leaf color. Students planted soybean seeds and then counted the number of seedlings of each genotype at day 7 and again at day 21. Seedlings of each genotype could be distinguished visually because the CG and CY alleles show incomplete dominance: CGCG seedlings have green leaves, CGCY seedlings have green-yellow leaves, and CYCY seedlings have yellow leaves. © 2014 Pearson Education, Inc. Using the day 7 data, what is the frequency of the CG allele (p)? a) p (2 49) (1 111) (0 56)/432 b) p (2 49) (1 111) (0 56)/216 c) p (2 23) (1 51) (0 26)/216 d) p (2 23) (1 51) (0 26)/432 © 2014 Pearson Education, Inc. Using the day 7 data, what is the frequency of the CG allele (p)? a) p (2 49) (1 111) (0 56)/432 b) p (2 49) (1 111) (0 56)/216 c) p (2 23) (1 51) (0 26)/216 d) p (2 23) (1 51) (0 26)/432 © 2014 Pearson Education, Inc. Using the day 7 data, what is the frequency of the CY allele (q)? a) 0.234 b) 0.484 c) 1.516 d) 1.484 © 2014 Pearson Education, Inc. Using the day 7 data, what is the frequency of the CY allele (q)? a) 0.234 b) 0.484 c) 1.516 d) 1.484 © 2014 Pearson Education, Inc. What is the expected genotype frequency for the CGCG genotype? a) p2 0.484 0.484 0.234 b) p2 0.484 0.516 0.250 c) p2 2 0.484 0.516 0.499 d) p2 0.516 0.516 0.266 © 2014 Pearson Education, Inc. What is the expected genotype frequency for the CGCG genotype? a) p2 0.484 0.484 0.234 b) p2 0.484 0.516 0.250 c) p2 2 0.484 0.516 0.499 d) p2 0.516 0.516 0.266 © 2014 Pearson Education, Inc. Calculate the observed genotype frequency for the genotype CGCY at day 7. a) 49 216 0.227 b) 111 216 0.514 c) 56 216 0.259 © 2014 Pearson Education, Inc. Calculate the observed genotype frequency for the genotype CGCY at day 7. a) 49 216 0.227 b) 111 216 0.514 c) 56 216 0.259 © 2014 Pearson Education, Inc. Compare the observed genotype frequencies you just calculated with the genotype frequencies expected if the population is in HardyWeinberg equilibrium. At day 7, is the seedling population in HardyWeinberg equilibrium, or is evolution occurring? a) The population is evolving, and there appears to be selection against genotype CGCY. b) The population is evolving, and there appears to be selection for genotype CGCG. c) The population is in Hardy-Weinberg equilibrium. d) The population is evolving, and there appears to be selection for genotype CYCY. © 2014 Pearson Education, Inc. Compare the observed genotype frequencies you just calculated with the genotype frequencies expected if the population is in HardyWeinberg equilibrium. At day 7, is the seedling population in HardyWeinberg equilibrium, or is evolution occurring? a) The population is evolving, and there appears to be selection against genotype CGCY. b) The population is evolving, and there appears to be selection for genotype CGCG. c) The population is in Hardy-Weinberg equilibrium. d) The population is evolving, and there appears to be selection for genotype CYCY. © 2014 Pearson Education, Inc. Compare the genotype frequencies at day 21 to the expected frequencies and the observed frequencies at day 7. Is the seedling population at day 21 in Hardy-Weinberg equilibrium, or is evolution occurring? a) The population is evolving, and there appears to be selection against genotype CYCY. b) The population is evolving, and there appears to be selection against genotype CGCG. c) The population is evolving, and there appears to be selection against genotype CGCY. d) The population is in Hardy-Weinberg equilibrium. © 2014 Pearson Education, Inc. Compare the genotype frequencies at day 21 to the expected frequencies and the observed frequencies at day 7. Is the seedling population at day 21 in Hardy-Weinberg equilibrium, or is evolution occurring? a) The population is evolving, and there appears to be selection against genotype CYCY. b) The population is evolving, and there appears to be selection against genotype CGCG. c) The population is evolving, and there appears to be selection against genotype CGCY. d) The population is in Hardy-Weinberg equilibrium. © 2014 Pearson Education, Inc. Homozygous CYCY individuals cannot produce chlorophyll. The ability to photosynthesize becomes more critical as seedlings age and begin to exhaust the supply of food that was stored in the seed from which they emerged. What hypothesis could explain the data for days 7 and 21? a) At day 7, CYCY individuals were not being selected against because they were using chlorophyll inherited from the mother plant; by day 21, they had run out of chlorophyll and many plants were not surviving. b) Some external factor caused a disproportionate number of deaths among the CYCY seedlings. If the experiment were repeated, the researchers would obtain a different result. c) At day 7, CYCY individuals were not being selected against because they had plenty of water; by day 21, they had run out of water and many plants were not surviving. d) At day 7, CYCY individuals were not being selected against because they had not used up the supply of food that was stored in the seed; by day 21, they had run out of stored food and many plants were not surviving. © 2014 Pearson Education, Inc. Homozygous CYCY individuals cannot produce chlorophyll. The ability to photosynthesize becomes more critical as seedlings age and begin to exhaust the supply of food that was stored in the seed from which they emerged. What hypothesis could explain the data for days 7 and 21? a) At day 7, CYCY individuals were not being selected against because they were using chlorophyll inherited from the mother plant; by day 21, they had run out of chlorophyll and many plants were not surviving. b) Some external factor caused a disproportionate number of deaths among the CYCY seedlings. If the experiment were repeated, the researchers would obtain a different result. c) At day 7, CYCY individuals were not being selected against because they had plenty of water; by day 21, they had run out of water and many plants were not surviving. d) At day 7, CYCY individuals were not being selected against because they had not used up the supply of food that was stored in the seed; by day 21, they had run out of stored food and many plants were not surviving. © 2014 Pearson Education, Inc. How do you expect the frequencies of the CG and CY alleles to change beyond day 21? a) The frequency of the CY allele will decrease, and the frequency of the CG allele will stay the same. b) The frequency of the CY allele will increase, and the frequency of the CG allele will decrease. c) The frequency of the CY allele will decrease, and the frequency of the CG allele will increase. d) The frequencies of the CY and CG alleles will stay the same. © 2014 Pearson Education, Inc. How do you expect the frequencies of the CG and CY alleles to change beyond day 21? a) The frequency of the CY allele will decrease, and the frequency of the CG allele will stay the same. b) The frequency of the CY allele will increase, and the frequency of the CG allele will decrease. c) The frequency of the CY allele will decrease, and the frequency of the CG allele will increase. d) The frequencies of the CY and CG alleles will stay the same. © 2014 Pearson Education, Inc.