Darwin's Postulates
Evolution
Variation
One of Darwin's postulates involves the idea that there is a lot of variety within a species. This meaning that phenotypes vary a lot within a species and that's why we are all somewhat different in many ways. With his idea of variation, we learn and understand how offsprings are born different with different genetics and varieties in traits and phenotypes. Darwin also stated that the variations are generally of two types—continuous variations or fluctuations and discontinuous variations. These variations may be neutral, harmful and useful as well.
Charles Darwin
This is a portrait of Darwin taken during the 19th century.
Variation in Butterflies
This clearly shows Darwin's idea of variation; showing the different types of wings in the specie of butterflies.
Variation in Frogs
Again we see the idea of variation in frogs, they have different colors, sizes, shapes etc.
Inheritance
This idea of inheritance means that offsprings have common traits or aspects from their parents; meaning that offsprings share DNA and genetics with their parents and relatives. This postulate was indeed one of the hardest for Darwin because he did not have information or knowledge on dominant and recessive traits. Because of inheritance we can clearly view specific species because if we did not have it then every organism would be different and therefore evolution would not be able to occur.
Differential Survival (Competition)
This postulate states that some organisms have stronger traits than others and by this some organisms can survive in an environment better than others. It is actually not a random process but depends on the strong trait if it is inherited or not. For example animals with stronger traits tend to survive best because they have the adaptation and the ability to be in a certain environment where they fit in perfectly and are able to survive completely.
Natural Selection
Natural selections selects the strong and weak traits of an organism.
Who is stronger?
All the fishes have different traits! Some weak, and some stronger traits.
Which one?
Which one is the strongest?
Survival of the Fittest
The fourth and last postulate states that the organisms with the strongest traits can survive at its best and therefore can reproduce more. This postulate is essential in evolution because the ones who are not the fittest are therefore required to evolve and protect themselves from danger or stronger organisms. For example, animal's teeth and claws evolve during years to help them be stronger and more effective in protecting themselves or their offsprings.
Survival of the Fittest
Bibliography
Benson, A. (n.d.). Survival of the fittest. Encyclopedia Britannica, Inc. Retrieved: April 07, 2016
http://global.britannica.com/science/survival-of-the-fittest
Evansville. (n.d.). Natural Selection. Retrieved April 07, 2016
http://faculty.evansville.edu/de3/b32003/lecture%20summaries/selection.pdf
Futuyma, D. (2004, December). Natural Selection: How Evolution Works. Retrieved April 07, 2016 http://www.actionbioscience.org/evolution/futuyma.html
Perez, L. (n.d.). The Meaning of Variations. Retrieved April 07, 2016 http://www.darwinismrefuted.com/origin_of_species_01.html