Wallace worked around the world gathering evidence to support his evolutionary theory. He is best known for studying warning colouration in animals, and examples include the Golden Birdwing Butterfly (Ornithoptera croesus).
After a variety of zoological discoveries Wallace proposed a theory of evolution, which matched Darwin's unpublished ideas that he had kept secret for nearly 20 years. This encouraged Darwin to collect his scientific ideas and collaborate with Wallace. Wallace produced scientific journals with Darwin in 1858, which prompted Darwin to publish On the Origin of Species the following year.