Final answer:
Charles Darwin did most of his evolutionary work during his voyage on the HMS Beagle, specifically through observations in the Galápagos Islands, which led to the development of his natural selection theory. His research there, alongside geological insights from Charles Lyell, contributed to the foundation of his evolutionary theories later published in 'On the Origin of Species'.
Step-by-step explanation:
Charles Darwin's Research and Observations
Charles Darwin conducted most of the work that led to his hypothesis on evolution during his voyage on the HMS Beagle, which took place from 1831 to 1836. This journey encompassed regions like South America, Australia, and the southern tip of Africa, with critical observations made in the Galápagos Islands. It was in the Galápagos that Darwin noted the distinct variations among ground finches, especially their beak shapes, which helped him formulate his theory of natural selection. He saw these adaptations as evidence that species could evolve from a common ancestor, adapting over time to their environment.
Observations that influenced Darwin’s ideas included the diversity of life in the tropical rainforests, evidence of an ancient and changing Earth such as fossil sea shells found high in the Andes, and the existence of extinct giant mammals. Moreover, Darwin's study of the Galápagos tortoises provided additional support for his theory. These experiences, combined with the confirmation from geologist Charles Lyell's writings about Earth's much older age, solidified Darwin's concept that life on Earth evolves over long periods.
Darwin's findings were meticulously recorded and later published in his groundbreaking work, On the Origin of Species, where he presented the theory that species evolve through the process of natural selection. His experiences in the Galápagos were a pivotal part of his life's work on evolution.