In an isolated population of mice, 10,000 mice are randomly sampled every 10 generations and their coat colors are recorded for a scientific study. The data for 100 generations of mice are shown in the graph below. Which of the following conclusions about the black and white mice in this population is best supported by the graph?

Question

In an isolated population of mice, 10,000 mice are randomly sampled every 10 generations and their coat colors are recorded for a scientific study.  The data for 100 generations of mice are shown in the graph below.  Which of the following conclusions about the black and white mice in this population is best supported by the graph?

Quizplus · Accepted Answer

11ecba2d_1017_e9ec_a3bf_4dfc2c5b3bb9_MD0008_00 Natural selection is an evolutionary process in which beneficial traits that improve a species' fitness are more likely to be passed on to the next generation than less favorable traits. Accordingly, beneficial traits become more common and deleterious traits become less common with each generation, allowing the species to adapt to its environment gradually. In this study, the coat colors of 10,000 mice were recorded every 10 generations. The graph shows that over 100 generations, the frequency of black mice graduallyincreased but the frequency of white mice decreased. Of all the answer choices, the conclusion that is best supported by the graph is that an environmental change resulted in natural selection that improved the survival and reproduction of black mice compared to white mice. Because such a change occurred gradually (over many generations), it is most likely that black coat color was selected for and that white coat color was selected against. (Choice A) Bottleneck events are sudden environmental changes that rapidly (not gradually) decrease the number of individuals in a population, often leading to reduced genetic diversity. If white mice in this population were lost due to a bottleneck event, their frequency would decrease in a short period (not over 100 generations). In addition, bottleneck events affect all members of the population randomly (regardless of genotype or phenotype). Therefore, a bottleneck event would also affect the frequency of black mice in the population. (Choices B and D) A speciation event leads to the formation of a new species from an existing species. Speciation may occur if two populations of a single species are separated for an extended period and become so genetically distinct that individuals are no longer able to reproduce with one another. The graph shows that black mice were already present at generation 0, so it is impossible for black mice to have been derived from either a speciation event in white mice or from a mating event between white mice. Educational objective: In natural selection, beneficial traits that improve fitness are more likely to be passed to subsequent generations than less favorable traits. Beneficial traits should become more common with each generation, allowing the species to adapt to its environment.

In an Isolated Population of Mice, 10,000 Mice Are Randomly