1.5 C: Role of the Environment in Evolution Quiz

Transcription

1 1. Numbers of reported cases of bedbug infestations have been increasing over the past ten years in the United States. In an attempt to combat the infestations, people began using pesticides to kill the bedbugs, but now many bedbugs are resistant to the two most common pesticides. The map below shows the percentages of bedbugs that are resistant to treatment in locations across the United States. The different shades in the pie chart for a certain location show the proportions of the population in that location that have mutations for resistance to one, both, or neither of the pesticides. Page 1 of 6

2 Which statements best explain how the two strains of resistance may have occurred and recommend the best course for future eradication of bedbugs? (A) The continued use of pesticides by humans has allowed bedbugs to adapt to the pesticides so that, if a bedbug survives an exposure, the bedbug will develop a resistance to the pesticide. To combat this resistance, stronger pesticides must be used. (B) When a bedbug population is almost eliminated by exposure to a pesticide, the bedbug population experiences a genetic bottleneck (genetic drift) that results in the expression of new genes. The new genes protect the survivors, so new bedbugs without the resistance genes should be introduced into the bedbug population to weaken the population s resistance to the pesticides. (C) The continued use of pesticides has selected for bedbugs that have some resistance to the pesticide, and over time the resistance has been passed on to offspring and increased within the population. To effectively deal with this resistance, different and new types of pesticides must be used. (D) The bedbug population can more effectively deal with low doses of various pesticides in the environment and is becoming immune to the pesticides. In order to effectively kill all bedbugs, one pesticide should be used at a time, and it should be used at a high concentration. Page 2 of 6

3 2. The Central European blackcap is a bird that spends its summers in Germany and historically spent its winters in Spain. About 50 years ago, however, backyard bird feeding became popular in Britain. With a ready supply of food in Britain, some blackcaps began to migrate northwest, instead of southwest to Spain, and were able to survive and return to their summer breeding grounds in Germany. (The birds begin their mating season soon after they arrive back in Germany from their wintering grounds. Migration is an innate, genetically controlled behavior.) Over time, the percentage of the population that migrates to Britain has increased. Today, about 10% of the population winters in Britain instead of Spain. The blackcap migratory routes are shown in the map below. The two populations of blackcaps have been studied, and the observations shown in the chart below have been made. These differences have taken only 30 generations to appear. Page 3 of 6

4 Which statements best explain the differences in phenotypes observed in the two blackcap populations? (A) The differences are due to the Britain-wintering blackcaps migrating to a new area and interbreeding with other populations of blackcaps. This interbreeding introduces new alleles into the population and changes the frequency of specific phenotypes in the area. (B) The differences are due to the Britain-wintering blackcaps migrating shorter distances and having different food sources in their winter habitats. These changes are selecting for different variations within the population and producing the changes observed. (C) The differences are due to the Spain-wintering blackcaps developing long wings and wide beaks over their lifetimes, whereas the Britain-wintering blackcaps do not develop these characteristics. The Spain-wintering blackcaps developed characteristics are passed directly to the next generation and add up over many generations. (D) The differences are due to the small population size of the Britain-wintering blackcaps. This small population has lost genetic diversity due to a genetic bottleneck, and as a result, random changes have occurred in gene frequencies and population phenotypes. Page 4 of 6

5 3. The graph below shows variation in the pigmentation of a frog population living in a Central American rain forest. This frog species is one of many green frog species that live in the rain forest, but this species displays a wider range of pigmentation phenotypes than most of the other green frog species. All of the green frog species are preyed upon by snakes, birds, and small mammals. A mutation occurs in this frog species that produces a toxic secretion from the skin, which does not hurt the frog but makes the frog taste unpleasant to predators. Which statement best predicts the likely change in pigmentation phenotype in the frog population as this mutation becomes more prevalent? (A) Because green pigmentation provides the best camouflage, there will be an increase in green pigmentation and a decrease in yellow-green and blue-green pigmentation, since these colors are easier to see in a rain forest environment. (B) Because female frogs find bright colors more attractive and the toxic secretions make camouflage less important, there will be an increase in yellow-green and blue-green pigmentation in the frog population. (C) Because toxic frogs with green pigmentation resemble other non-toxic green frogs, there will be an increase in yellow-green and blue-green pigmentation, since these colors are easier for predators to recognize and avoid. (D) Because blue pigmentation is more commonly associated with toxic organisms than yellow or green pigmentations are, there will be an increase in blue-green pigmentation and a decrease in yellow-green and green pigmentation, as species with these phenotypes will be mistaken for non-toxic species and will suffer higher rates of predation. Page 5 of 6

6 4. Biologists are studying how the unique environmental conditions found in Africa s Lake Victoria may affect the cichlid fish living in the lake. The cichlid fish are present in a wide diversity of colors. Due to the presence of yellow-green phytoplankton and dissolved organic matter in Lake Victoria, blue light dominates the visual environment at the surface, but in deep water, red light dominates. Female cichlids prefer to mate with brightly colored males, and blue males will reflect more blue light while red males reflect more red light, so there is a population of blue cichlids in shallow water and a population of red cichlids in deep water. Recent logging around the lake has caused the water to become cloudy with silt (pieces of fine sand and clay), and now neither blue nor red light travels to significant depths in the lake. Which statement predicts what is most likely to occur in the cichlid populations in Lake Victoria if the cloudy water conditions persist for a long time? (A) Because there is no longer a selective advantage to having red or blue coloration for males at either depth, neither color will be favored at either depth, and the two populations will begin to interbreed and lose their unique colorations. (B) Because the water is cloudy with silt, brown-colored cichlids will be favored by the females and will have a selective advantage in both populations. (C) Because the water is cloudy and the fish cannot see through the silt, the fish will lose both their coloration and their ability to see, since neither trait will be needed for their survival. (D) Because the females at the bottom of the lake favor red males and the females near the top of the lake favor blue males, the populations will remain unchanged due to female preference being genetically determined. Page 6 of 6