How did adaptive radiation produce the diversity of Galapagos finches?

The diversity of Galapagos finches is a classic example of adaptive radiation, a process where a single ancestral lineage rapidly diverges into multiple species to exploit various ecological niches.1

When the ancestral finch arrived at the remote Galapagos Islands, it encountered an environment with few competitors and an abundance of unoccupied ecological niches. Because these niches were not already filled by other bird groups, the descendants of the original colonizer were able to evolve specialized traits to survive in diverse habitats and diets.21

This divergence is most clearly reflected in the configuration of their bills, which evolved into distinct shapes suited for specific feeding habits—such as probing, grasping, biting, or crushing. Through this process of evolution, the ancestral population split into 14 distinct species, each adapted to exploit specific food sources, ranging from plant-based diets to insect-heavy ones. This rapid diversification provided Charles Darwin with critical evidence for his theory that species are not immutable.21