John Thomas Gulick (March 13, 1832 – April 14, 1923) was an American missionary and naturalist from Hawaii. He was one of the pioneers of modern evolutionary thinking based on his studies of Hawaiian snails of the genus Achatinella. He was among the first to describe the formation of species through geographic separation of breeding populations. He developed early ideas on the founder effect and what is now known as the Baldwin effect. He coined the term "divergent evolution". Life Gulick was born in Waimea on Kauai Island, during the Kingdom of Hawaii. His father was missionary Peter Johnson Gulick (1796–1877) and mother was Fanny (Thomas) Gulick (1798–1883). Early in life he went to Oregon and sought gold in California. In 1851, he started to collect and study Hawaiian land snails. He had been interested in snails (a field now known as Conchology) since his early teens, and developed independently the concept of their evolution. He discovered many species of snails were only found in very specific areas within the islands, and there was no overlap between these areas. In 1853, after reading Charles Darwin's The Voyage of the Beagle and Hugh Miller's The Footprints of the Creator, Gulick presented his paper, "The Distribution of Plants and Animals", to the Punahou School Debating Society. In 1855, he enrolled for one year at New York University and then Williams College in Massachusetts, and studied in their Lyceum of Natural History. In 1859, he was elected Lyceum President, and graduated with an A.B. degree. He then followed the family tradition of attending theological school at Williams College (1859) and enrolled in Union Theological Seminary in New York City from 1859 to 1861. While there, he read Darwin's On the Origin of Species. He then collected shells in Panama and Japan. On August 22, 1864, Gulick was ordained as a missionary in China, but also continued his study of snails. On September 3, 1864, he married Emily de la Cour. In 1872, he wrote "On the Variation of Species as Related to Their Geographical Distribution, Illustrated by the Achatinellinae", which was published in the journal Nature. In 1872, he traveled to England for two years. While there, he corresponded with Charles Darwin regarding his studies. He finally met Darwin and gave him a synopsis of an upcoming paper. That paper was "On Diversity of Evolution Under One Set of External Conditions", which was