Darwin's Four Postulates
Darwin’s four postulates are the simple criteria that explains the process of natural selection.
Natural Selection: The survival of the fittest. The individuals with certain heritable traits tend to produce more surviving offspring than the individuals without those traits.
1) Individual Variation
2) Inheritance of Variations
3) In every generation, more offspring are produced than can survive
4) Survival and reproduction are not random
E.g.) After the drought, finches with deep beaks survived. In this new environment, they were the fittest. Because the average survivor had a deeper beak, the average beak size of the population changed.
Things to consider...
Evolution ≠ Natural Selection
Natural Selection = One of the mechanisms of evolution, as a result of adaptation
Florida International University. (2012). Darwinian natural selection [PDF file]. Retrieved April 4, 2016, from http://bioserv.fiu.edu/ortegaj/CHAPTER3_DARWIN_SPR.pdf
Freeman, S., Quillin, K., & Allison, L. (2013). Biological Science (5th ed.). San Francisco, CA: Benjamin Cummings.
University of California. (2002). Introduction to Ecological Genetics. Retrieved April 4, 2016, from http://ib.berkeley.edu/courses/ib162/Week1.htm