Natural Selection in Biology: A Gizmo Exploration

Biology - Natural Selection Gizmo 1. Which of the following statements best describes what will most likely occur to the moth populations in the image below? The light moths will be captured by predators more easily than the dark moths, and the population of dark moths will rise. Explanation: The light moths are highly visible to predators against the dark tree, but the dark moths are nearly invisible to predators. So, it is likely that more light moths will be captured by the predators, causing the population of light moths to decrease. The dark moth population will increase because there are more of them to reproduce. 2. What is the most likely The moths are living in an environment with dark explanation of the data trees. shown below? Explanation: Since the population of dark moths is rising and the population of the light moths is falling, you can assume that the dark moths have some sort of advantage over the light moths. If the trees in their environment were dark, that would be an advantage to the dark moths, because they would be better camouflaged on the dark trees. 3. The pair of population graphs below display the results of two different five-year hunting cycles, one on light trees and one on dark trees. The population of light-colored moths is shown by the light gray dots, and the population of dark moths is shown by the dark gray dots. How do these results demonstrate natural selection? The moths that were the same color as their background were more likely to survive and reproduce. Over time, the populations of these well-adapted moths increased. Explanation: The graphs show that the populations of moths that were the same color as the trees increased, while the populations of moths that were the opposite color as the tree decreased. The moths that were the same color as the trees were better hidden and less likely to be eaten by birds. These moths were more likely to survive and produce offspring. Over time, the populations of well-camouflaged moths increased, and poorly-camouflaged moths died out. 1/2 4. Suppose a certain species of insect lives in the lush green canopy of the rain forest. Some of the insects are bright green in color, and some are bright yellow. Assume there is a natural predator of the insect in the area. What do you expect to happen to the populations of the green and the yellow insects over time? The green insect population will increase and the yellow insect population will decrease 5. Natural selection can operate on predator populations as well as on prey. Suppose that over time trees became covered in lichen and the proportion of light moths increased to nearly 100%. What is the most likely consequence for predator populations? All of the above. Explanation: In the green rain forest, it is likely that the green insects would have some natural camouflage, while the yellow insects would be easily visible to the predator. Therefore, it is likely that, over time, the predator would capture and eat more of the yellow insects than the green ones. This would cause the green insect population to increase and the yellow insect population to decrease. Explanation: When nearly 100% of the moths are well-camouflaged, it will be harder for birds to catch moths, and fewer birds will survive. The birds that do survive are likely to have very sharp vision, can find an alternative food source or use a different hunting strategy, such as hunting in the evening when the moths are more likely to be flying. 2/2