Gene pool describes the sum of all genetic variations (alleles) within a species. Many variations is considered healthy for a population of a species, whereas little genetic diversity (as in a monoculture or due to inbreeding) is considered harmful.
... years later he was sent to Hawaii, where he was ordained on May 24, 1864. On May 10, 1873, at his request, he was permitted to travel to Molokai to help the lepers who ...