Northern elephant seals are large marine mammals that live off the coast of southern California. In the late 1800s, they were hunted to near extinction. Conservation efforts by the Mexican government in the early 20th century restored their numbers with a breeding population of fewer than 100 individuals.
As a result, the northern elephant seal population demonstrates far less genetic diversity than southern elephant seals.
The hunting of the northern elephant seal population created which of the following phenomena resulting in the reduction of the population's genetic diversity?