📝 Coat Coloration in mice (7 MCQs)
📖 From Campbell Biology • 1. Evolution and the theme of Biology and Scientific Inquiry • 7 questions available
What is Coat Coloration in mice?
Definition:
Coat coloration in mice is a classic example of evolutionary adaptation, where the color of mice varies depending on their habitat, with beach mice having lighter, sandy-colored coats and inland mice having darker, brownish coats, and this coloration provides camouflage against predators, serving as a model system for studying natural selection and the genetic basis of adaptation.
Working:
Coat coloration in mice works by providing crypsis (camouflage) that reduces predation: beach mice with light coloration blend into the sandy beaches, while inland mice with dark coloration blend into the dark soil and vegetation, and this adaptation is under genetic control, with specific alleles (e.g., the Mc1r gene) being responsible for the color differences, and the variation in coat color is maintained by natural selection, where predators are more likely to spot mismatched individuals.
Example:
A simple example is the Florida beach mouse (Peromyscus polionotus), which has a light-colored coat that matches the white sands of the Gulf Coast, while its inland relative has a darker coat, and experimental studies have shown that mice with coat color that matches their background have higher survival rates, illustrating the adaptive value of coat coloration.
Reason:
Studying coat coloration in mice is important for understanding natural selection, adaptation, and the genetics of color variation, and it provides a clear, tractable system for testing evolutionary hypotheses in the field and lab, contributing to our knowledge of how organisms adapt to their environments.
📝 All Coat Coloration in mice MCQs
Q1. A researcher observes that mice living on dark volcanic soil are predominantly dark-coated, while mice on nearby light soil are mostly light-coated. Which interpretation best explains why this pattern is scientifically interesting?
📖 Explanation: The observation is interesting because a consistent association between coat color and habitat can suggest natural selection if color affects survival. It does not by itself prove causation, because inheritance, migration, predation, and other environmental factors could also contribute.
Q2. Suppose dark-coated mice are harder for predators to detect on dark ground. Over several generations, what population-level change would most strongly support the idea that natural selection is acting on coat coloration?
📖 Explanation: If coat color is heritable and darker mice survive and reproduce more successfully in the dark habitat, alleles associated with darker coloration should become more common over generations. The key evidence is a population-level change in inherited variation, not an individual color change.
Q3. A scientist compares two mouse populations. Population X has 80% dark-coated mice and lives on dark soil; Population Y has 20% dark-coated mice and lives on light soil. Which additional observation would provide the strongest evidence that camouflage contributes to this difference?
📖 Explanation: Predation data directly connect coat coloration with differential survival, strengthening the proposed mechanism. Differences in body size, vegetation, or the mere presence of both phenotypes do not establish that camouflage causes the observed difference in population frequencies.
Q4. A researcher concludes, 'Because dark-coated mice are more common on dark soil, the soil must have caused individual mice to develop dark fur.' What is the main flaw in this reasoning?
📖 Explanation: The observed association between habitat and coat color does not distinguish environmental induction from inherited variation followed by differential survival. A stronger investigation would examine inheritance and fitness, because natural selection changes population frequencies across generations rather than simply changing individuals.
Q5. A graph shows that after 10 generations, dark-coated mice increase from 30% to 75% in a dark-soil habitat, while their frequency remains near 30% in a light-soil habitat. Which conclusion is best supported by these data?
📖 Explanation: The contrasting frequency changes suggest that the advantage of dark coloration depends on environmental context. This is consistent with selection for camouflage, but the graph alone does not prove the precise mechanism or rule out every other ecological factor.
Q6. Two researchers test the same hypothesis. Researcher A measures coat-color frequencies only once in several habitats. Researcher B measures coat-color frequencies across multiple generations while also recording predator attacks. Why is Researcher B's design more informative?
📖 Explanation: Repeated measurements across generations reveal whether inherited trait frequencies change over time, while predator observations provide evidence about differential survival. Combining these observations gives stronger support for a selection-based explanation than a single snapshot of populations.
Q7. A particularly challenging result is found: dark-coated mice survive better on dark soil, but their frequency does not increase over generations. Which explanation best resolves this apparent contradiction?
📖 Explanation: A survival advantage alone does not guarantee a rapid evolutionary increase. The advantage must be associated with heritable variation and produce a sufficient difference in reproductive contribution. Gene flow, mating patterns, genetic constraints, or other selective pressures could counteract the observed survival difference.