Adaptive radiation refers to the rapid diversification of an ancestral species into multiple new species, each adapted to exploit specific niches within a given environment. This phenomenon often occurs when a new habitat becomes available, when a new ecological opportunity arises, or when a major extinction event clears out potential competitors.
Several factors can drive adaptive radiation:
1. Ecological Opportunity: When new resources or spaces become available in an environment, a species might diversify to exploit these opportunities. For instance, if a species of plant develops a novel method of obtaining nutrients, its descendants could radiate into various forms, each adapted to a specific nutrient source.
2. Morphological Innovation: Evolutionary changes in anatomy or physiology can enable species to explore and exploit new ways of life. For example, the development of wings in ancestral birds opened up aerial niches.
3. Geographic Isolation: When populations of a species become separated due to geographic barriers (like mountains or oceans), they may evolve separately and diversify based on the specific challenges and opportunities of their new habitats.
One of the most famous examples of adaptive radiation is the diversification of the finches on the Galápagos Islands, which were studied extensively by Charles Darwin. These birds originated from a single ancestral species but evolved into multiple distinct species, each with unique beak shapes adapted to different food sources available on the different islands.
Another example is the radiation of cichlid fish in East African lakes. In the relatively short span of a few million years, hundreds of cichlid species evolved, each adapted to different ecological niches in their respective lakes.