Which describes an example of exaptation?

• A. The peppered moth evolved a dark color in response to a change in the environment, but then, as the environment again changed, light color became more common.
• B. Octopus and vertebrate eyes are structured and function very similarly but evolved independently.
• C. Mammals began to diversify rapidly after the end-Cretaceous extinction event as they evolved to fill ecological niches previously occupied by dinosaurs.
• D. Mammary glands (milk-producing glands in mammals) are thought to have evolved from apocrine glands, which are sweat/oil glands typically associated with hair follicles.

Answer: (D)

Verified step by step guidance

1. Understand the concept of exaptation: Exaptation refers to a trait that has been co-opted for a use other than the one for which natural selection has built it. It involves the evolution of a function that was not originally intended for the trait.
2. Identify the key elements of the problem: The problem provides several examples of evolutionary changes and asks which one describes exaptation.
3. Analyze the examples given: The first example describes a change in color in response to environmental changes, which is an adaptation rather than exaptation. The second example involves convergent evolution, where similar traits evolve independently, not exaptation. The third example describes diversification after an extinction event, which is adaptive radiation, not exaptation.
4. Focus on the correct answer: The example of mammary glands evolving from apocrine glands fits the definition of exaptation. Apocrine glands originally served a different function (sweat/oil production) and were co-opted for milk production in mammals.
5. Conclude with the understanding that exaptation involves the repurposing of existing structures for new functions, as seen in the evolution of mammary glands from apocrine glands.