Glossary of "Evolution (4th ed.)" by Futuyma & Kirkpatrick (2017)
Glossary of "Ancestors in Our Genome" by Harris (2015)
- Geographically contiguous populations of a widespread species will meet at zones where they show reduced or limited interbreeding. Over time the two populations can become reproductively isolated even in the midst of continued but slowing gene flow and become different species.
- Futuyma, D. J. & Kirkpatrick, M. 2017. Evolution, 4th ed. -xviii + 602 pp. Sinauer Associates, Inc., Sunderland.
- Harris, E. E. 2015. Ancestors in Our Genome: the New Science of Human Evolution. - xx + 226 pp. Oxford University Press, New York.