Final answer:
Adaptive radiation is the process by which a single species evolves into multiple distinct species as a result of dispersal to diverse environments and exploitation of different niches, often facilitated by geographical isolation, such as on island archipelagos.
Step-by-step explanation:
Adaptive radiation occurs when a population of a single species disperses and finds distinct niches or isolated habitats. Over time, due to the varied demands of their new environments, multiple speciation events occur, with many adaptations evolving from a single point of origin.
This process allows the species to radiate into several new ones. Island archipelagos, like the Hawaiian Islands, are ideal for adaptive radiation due to geographical isolation. An example of this is the Hawaiian honeycreeper, which evolved from a founder species into numerous distinct species.
Circumstances that lead to adaptive radiations often include ecological opportunities such as the availability of unoccupied niches, environmental changes that open new habitats or resources, and the evolution of key innovations that allow a species to exploit resources in a new way.
Geographical isolation also plays a crucial role in adaptive radiation by preventing gene flow between populations, facilitating divergent evolution.