Self-tutoring about biology: the tutor mentions the term relict.
relict (noun): a population that was once included by a larger one, but has grown isolated due to changing conditions.
Changing climatic conditions can cause relicts, as can changing geography (collapse of a land bridge, for instance).
Barber, Katherine et al. Oxford Canadian Dictionary of Current English. Don Mills: Oxford University Press, 2005.Jack of Oracle Tutoring by Jack and Diane, Campbell River, BC.