Founder effect is a phrase that came up recently in our conversations about speciation. It refers to a situation where genetic diversity is somewhat limited due to a small initial "founding" population.
Some good examples can be found in Mark Ridley's Evolution A -Z. These include Ernst Mayr's observation that founder effect is "The establishment of a new population by a few original founders (in an extreme case a single fertilized female) which carry only a small fraction of the total genetic variation of the parental population."
Evolution - A-Z - Founder effect. (n.d.). Evolution - A-Z - Founder effect. Retrieved October 23, 2013, from http://www.blackwellpublishing.com/ridley/a-z/Founder_effect.asp
Evolution: Library Genetic Drift and Founder Effect. Retrieved December 1, 2013, from http://www.pbs.org/wgbh/evolution/library/06/3/l_063_03.html.
Founder Effect, Bottle Necking, and Genetic Drift. (2010, December 27). YouTube. Retrieved October 28, 2013, from http://www.youtube.com/watch?v=Q6JEA2olNts
Founder effect. (n.d.). Founder effect. Retrieved October 28, 2013, from http://www.umbc.edu/bioclass/biol100/powerpoints/lecture10/sld032.htm