During his fieldwork in the Malay Archipelago, Alfred Russel Wallace identified a sharp faunal boundary (now known as the 'Wallace Line') separating species of Asian origin from those of Australasian origin, despite the highly similar tropical climates on either side of the line.
Which of the following best explains how this biogeographical observation serves as evidence for evolution by natural selection?
It demonstrates that species distribution is determined by evolutionary history and geographic barriers rather than climate alone, showing that isolated populations adapt from different ancestral lineages over time.
It proves that identical tropical climates induce identical beneficial mutations in unrelated species, leading to rapid convergent evolution across the oceanic gap.
It supports the hypothesis that organisms actively mutate their own DNA sequence in direct response to geographic barriers to ensure their survival.
It illustrates that geographical barriers have no effect on natural selection, as species on both sides of the line remain identical due to continuous gene flow.
