Adaptive radiations are often seen after __________.

• A. sexual selection takes place
• B. major new evolutionary adaptations, such as flight, occur
• C. mass extinctions
• D. sympatric speciation events
• E. The second and third responses are correct.

Answer: (E)

Verified step by step guidance

1. Understand the concept of adaptive radiation: Adaptive radiation is the process by which organisms diversify rapidly into a multitude of new forms, particularly when a change in the environment makes new resources available, creates new challenges, or opens new environmental niches.
2. Consider the context of major new evolutionary adaptations: When a significant evolutionary adaptation occurs, such as the development of flight in birds, it allows organisms to exploit new environments and resources, leading to adaptive radiation.
3. Analyze the impact of mass extinctions: Mass extinctions remove a large number of species, which reduces competition and allows surviving species to diversify and fill the vacant ecological niches, resulting in adaptive radiation.
4. Evaluate the role of sexual selection: While sexual selection can lead to speciation, it does not typically result in the broad diversification seen in adaptive radiations.
5. Assess sympatric speciation events: Sympatric speciation involves the evolution of new species from a single ancestral species while inhabiting the same geographic region. It can contribute to diversity but is not a primary driver of adaptive radiation like major evolutionary adaptations or mass extinctions.