Darwin hypothesized that new species could appear gradually through small changes in an ancestral species. what experiment did he conduct to test this hypothesis?

Answer;
He conducted an experiment with breeding pigeons. 

Explanation;
The pigeons provided the perfect animal to test his theory of selection for quite a number of reasons including its trait diversity from wing structures to color patterns to size to flight patterns. From these experiments he concluded that by natural selection of randomly occurring traits that make species better suited for survival and reproduction, evolve in the astounding diversity of organisms on Earth today.