Final answer:
The Galapagos Islands were populated by species through over-water dispersal and adaptive radiation from South America, leading to a diversity of lifeforms, such as Giant Tortoises and finches, which exhibit adaptations for island life and provide evidence of natural selection.
Step-by-step explanation:
The Galapagos Islands were populated by species through two main methods: over-water dispersal and adaptive radiation. These islands are renowned for their unique biodiversity and the role they played in Charles Darwin's development of the theory of natural selection. Various lifeforms, such as the Giant Tortoises with differing shell shapes, and finches with specialized beak structures, showcase the islands' role in enhancing our understanding of speciation and adaptation. Species arrived from the nearby continent, which is South America, and evolved over generations to adapt to the distinct environments on each island.
For instance, Marine Iguanas and Land Iguanas demonstrate trait divergence, where one became aquatic, feeding on seaweed, and the other remained terrestrial, eating cactus. Similarly, the finches that Darwin studied exhibit adaptive radiation, where one species diversified into many to exploit different ecological niches, showing clear evidence of evolution. The origin of these species likely traces back to a common ancestor that arrived from the South American mainland and subsequently evolved to adapt to the varied habitats of the Galapagos archipelago.