Darwin hypothesized that new species could appear gradually through small changes in an ancestral species. which observation that he made about finches most supports that hypothesis?

The observation that he made about finches that supports Darwin’s hypothesis is the genetic drift. Genetic drift, the founder principle, and the bottleneck effect all occur under the conditions when the majority of a population is decimated and there are only a few remaining organisms left to rebuild the population.  This will cause new species could appear gradually through small changes in an ancestral species.

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