Darwin's Four Postulates
1: There is Variation Among Individuals
2. Some of the Variation is Heritable
3. Do individuals vary in Their Success at Reproducing?
4. Is Reproduction nonrandom?
Natural selection. (2016).Evolution.berkeley.edu. Retrieved 6 April 2016, from http://evolution.berkeley.edu/evolibrary/article/evo_25
Reproduction, a high quality journal publishing research into the cellular and molecular biology of reproduction . (2016). Reproduction-online.org. Retrieved 6 April 2016, from http://www.reproduction-online.org/
variation | biology. (2016). Encyclopedia Britannica. Retrieved 6 April 2016, from http://global.britannica.com/science/variation-biology