When a species invades a new area, especially an island, the original, small population is called a founder population. The concept of a founder population is usually used in a context of subsequent population growth, and populations that have recently arisen from small founder populations will exhibit reduced variation due to the genetic drift implied by such a population bottleneck.

Founder populations are essential to the study of island biogeography. A natural tabula rasa is not easily found. Classic series of studies on founder population effects were done following the catastrophic eruption in 1883 of Krakatau, ('Krakatoa'), which erased all life on the island remnant. Another ongoing study has been following the biocolonization of Surtsey, Iceland, a new volcanic island that erupted offshore between 1963 and 1967.