Adaptive melanism describes selection for _. a. mottled pigmentation b. lighter pigmentation c. darker pigmentation d. more colorful pigmentation
The Correct Answer and Explanation is :
The correct answer is c. darker pigmentation.
Explanation:
Adaptive melanism refers to the evolutionary process where organisms develop darker pigmentation as an adaptive response to environmental pressures. This phenomenon is often seen in various species of animals, such as moths, rodents, and reptiles, where darker individuals have a selective advantage in certain environments. The selection for darker pigmentation is often driven by factors like camouflage, predation pressures, or climate.
In many cases, darker pigmentation enhances an organism’s ability to blend into its environment, offering protection from predators. A well-known example is the case of the Biston betularia moth during the Industrial Revolution in England. Before industrialization, the moths had light-colored wings, which helped them camouflage against the light-colored lichen on trees. However, as industrial pollution darkened the trees and surrounding environment, the darker, melanic forms of the moths had a better chance of survival. These dark moths were less visible to predators such as birds, leading to an increase in their population over time.
Adaptive melanism is also observed in animals living in hot environments. Dark pigmentation can increase the absorption of heat from the sun, which might help regulate body temperature. For example, in some species of lizards or snakes, darker colors help them warm up more efficiently in cooler environments.
While adaptive melanism typically refers to the development of darker pigmentation, it is important to note that evolution does not always favor darker traits. In some cases, lighter pigmentation might be selected if it offers a better camouflage or other survival advantages. However, in the context of adaptive melanism, the primary focus is on the evolutionary advantages of darker pigmentation in specific environmental conditions.