Which of the following best explains why a frog is typically lighter on its ventral side and darker on its dorsal side?

• A. This coloration provides camouflage from both aerial and aquatic predators, a phenomenon known as countershading.
• B. The lighter ventral side helps the frog absorb more sunlight for thermoregulation.
• C. The color difference is a result of random genetic drift with no adaptive significance.
• D. Darker dorsal coloration is used to attract mates during the breeding season.

Answer: (A)

Verified step by step guidance

1. Understand the concept of countershading: Countershading is a form of camouflage where an organism has a darker dorsal (top) side and a lighter ventral (bottom) side. This adaptation helps the organism blend into its environment and avoid predators.
2. Analyze the adaptive significance of countershading: The darker dorsal side helps the frog blend into the ground or vegetation when viewed from above, protecting it from aerial predators. The lighter ventral side helps the frog blend into the lighter sky or water surface when viewed from below, protecting it from aquatic predators.
3. Evaluate the incorrect options: The lighter ventral side does not primarily help with thermoregulation, as frogs rely on behavioral adaptations like basking to regulate their temperature. Random genetic drift does not explain the consistent presence of countershading across many species, as it is an adaptive trait. Darker dorsal coloration is not used to attract mates; frogs typically use vocalizations and other behaviors for mating.
4. Identify the correct explanation: Countershading provides camouflage from both aerial and aquatic predators, making it an adaptive trait that increases the frog's chances of survival.
5. Conclude that the correct answer is: 'This coloration provides camouflage from both aerial and aquatic predators, a phenomenon known as countershading.'