📝 Camouflage hypothesis supported (7 MCQs)
📖 From Campbell Biology • 1. Evolution and the theme of Biology and Scientific Inquiry • 7 questions available
What is Camouflage hypothesis supported?
Definition:
The camouflage hypothesis is supported when experimental evidence shows that organisms with coloration matching their background have higher survival rates or lower predation rates than those with mismatched coloration, providing empirical validation that natural selection acts on color patterns to enhance camouflage, and this support comes from field and lab experiments that demonstrate the adaptive value of crypsis.
Working:
Support for the camouflage hypothesis is generated through experiments where predation on matching vs. mismatching models or live animals is compared, and statistical analysis (e.g., chi-square tests) shows significantly lower predation on matching individuals, with a p-value less than 0.05 indicating that the difference is unlikely due to chance; multiple studies across different species and habitats have supported this hypothesis, making it a well-established example of adaptation by natural selection.
Example:
A simple example is the classic experiment with mouse models where dark and light models were placed on dark and light backgrounds; the data showed that dark models on dark backgrounds and light models on light backgrounds had significantly fewer bite marks, supporting the camouflage hypothesis, and this result has been replicated in various systems, from moths to snakes, confirming the importance of camouflage.
Reason:
Support for the camouflage hypothesis is important because it provides direct evidence of natural selection, demonstrating how environmental pressures shape evolution, and it reinforces the fundamental principles of evolutionary biology, making it a classic case study in biology education.
📝 All Camouflage hypothesis supported MCQs
Q1. Researchers place equal numbers of light-coated and dark-coated model mice in two habitats. After several days, more light models remain on pale sand, while more dark models remain on dark soil. Which conclusion is best supported by these results?
📖 Explanation: The pattern of survival is consistent with camouflage because individuals whose coats contrast less with the background appear less detectable. However, the results support a relationship between coloration and predation risk rather than proving that habitat color directly changes genes.
Q2. Suppose dark-coated mice survive at a higher rate on dark soil, while light-coated mice survive at a higher rate on pale sand. Why is this pattern stronger evidence for camouflage than simply observing that the two mouse populations have different coat colors?
📖 Explanation: Different coat frequencies alone cannot reveal why the populations differ. When survival changes predictably with the match between coat color and background, the evidence links coloration to reduced detectability and therefore provides stronger support for camouflage.
Q3. A population of mice is moved from dark soil to pale sand. If camouflage is important, which prediction would most logically follow when predators remain present?
📖 Explanation: Changing the background alters how conspicuous each coat is. If predators rely on visual detection, dark mice should become easier to notice against pale sand, increasing their expected predation risk compared with mice whose coloration better matches the new background.
Q4. A student concludes, 'Because dark-coated mice were more common in the dark habitat, the dark environment must have caused individual mice to become dark during their lifetimes.' What is the main flaw in this reasoning?
📖 Explanation: The observed association does not demonstrate that individual mice changed their coat color because of the environment. Population differences can arise because existing variation affects survival and reproduction, so the student's explanation goes beyond what the evidence establishes.
Q5. A graph shows the percentage of model mice remaining after exposure to predators: light mice on pale sand = 78%, dark mice on pale sand = 42%, light mice on dark soil = 39%, and dark mice on dark soil = 76%. Which interpretation best fits the pattern?
📖 Explanation: The two highest survival percentages occur when coat color matches the background, while the two lowest occur when coloration contrasts with it. This interaction between coat color and habitat background is consistent with reduced visibility to predators.
Q6. Two experiments test the same idea. Experiment X compares light and dark mice only on pale sand. Experiment Y compares both coat types on pale sand and dark soil, using the same predator exposure. Which experiment provides stronger evidence for camouflage and why?
📖 Explanation: Camouflage predicts that the benefit of a particular coat depends on the background. Experiment Y directly tests this interaction by comparing both coat types across contrasting environments, making it more informative than a single-background comparison.
Q7. In a controlled study, researchers find that well-camouflaged models survive more often, but the difference disappears when predators are excluded. Which combined interpretation is most reasonable?
📖 Explanation: The disappearance of the survival difference without predators is important because it identifies a plausible mechanism connecting coloration to survival. Together, the findings suggest that reduced visibility matters specifically when predators can remove conspicuous individuals.