Glossary of Plant Systematics (1st ed.) by Simpson (2006)
- The splitting of one ancestral population into two (or more) populations, such as by continental drift or the formation of a geographic barrier.
Glossary of "Evolution (4th ed.)" by Futuyma & Kirkpatrick (2017)
- Separation of a continuously distributed ancestral population or species into separate populations because of the development of a geographic or ecological barrier.
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.
- Futuyma, D. J. & Kirkpatrick, M. 2017. Evolution, 4th ed. -xviii + 602 pp. Sinauer Associates, Inc., Sunderland.