Glossary of "Plant Systematics (1st ed.)" by Simpson (2006)
- The directed and nonrandom genetic modification of a population or species, in which genetic changes that result in an increase in survivorship and/or reproduction are contributed to the next generation more.
Glossary of "Ecology (6th ed.)" by Krebs (2009)
- the process in nature by which only the organisms best adapted to their environment tend to survive and transmit their genetic characteristics to succeeding generations while those less adapted tend to be eliminated.
Glossary of "Life (9th ed.)" by Sadava et al. (2011)
- The differential contribution of offspring to the next generation by various genetic types belonging to the same population. The mechanism of evolution proposed by Charles Darwin.
Glossary of "Ancestors in Our Genome" by Harris (2015)
- the differential survival or reproduction of individuals based on their fitness within the specific environment in which they live.
Glossary of "Environmental Science: Earth as a Living Planet (2nd ed.)" by Botkin & Keller (1998)
- A process by which organisms whose biological characteristics better fit hem to the environment are better represented by descendants in future generations than those whose characteristics are less fit for the environment.
"A Dictionary of Ecology, Evolution and Systematics (2nd ed.)" by Lincoln et al. (1998)
- The non-random and differential reproduction of different genotypes acting to preserve favourable variants and to eliminate less favourable variants; viewed as the creative force that directs the course of evolution by preserving those variants or traits best adapted in the face of natural competition.
- Botkin, D. B. & Keller, E. A. 1998. Environmental Science: Earth as a Living Planet, 2nd ed. -xxxxii + 649 pp. John Wiley & Sons, Inc., New York.
- Harris, E. E. 2015. Ancestors in Our Genome: the New Science of Human Evolution. - xx + 226 pp. Oxford University Press, New York.
- Krebs, C. J. 2009. Ecology, 6th ed. -xvi + 655 pp. Pearson Benjamin Cummings, San Francisco.
- Lincoln, R., Boxshall, G. & Clark, P. 1998. A Dictionary of Ecology, Evolution and Systematics. ix + 361 pp. Cambridge University Press, Cambridge.
- Sadava, D., Hillis, D. M., Heller, H. C. & Berenbaum, M. R. 2011. Life: The Science of Biology, 9th ed. -xliv + 1266 pp. Sinauer Associates, Inc., Sunderland.
- Simpson, M. G. 2006. Plant Systematics. -xi + 590 pp. Elsevier Academic Press, Oxford.