Final answer:
On the Voyage of the HMS Beagle, Darwin's discoveries in biogeography and species adaptation, particularly amongst the Galápagos finches and tortoises, influenced his theory of natural selection.
Step-by-step explanation:
During the Voyage of the HMS Beagle, Charles Darwin made groundbreaking observations that significantly contributed to the field of biogeography and the development of his theory of natural selection.
One pivotal discovery was in the Galápagos Islands, where Darwin noted distinct species of finches with varied beak shapes and sizes adapted to different food sources. He pondered the possibility that these species may have evolved from a common ancestor, similar to a species found on the mainland of South America. These observations indicated that species adaptation and differentiation could occur based on the environmental conditions of different geographical locations.
Additional discoveries included the variation among Galápagos tortoises, which varied from island to island. This led Darwin to question how species originate and suggested a link between geographic separation and species divergence. The biogeographical patterns established during this voyage contributed significantly to Darwin's later work, "On the Origin of Species." The concept of species changing over time through natural selection, influenced by their geographic surroundings, laid the foundation for evolutionary biology as we understand it today.