Darwin's Postulates

Regina Zambrano

The four factors that drive the process of evolution as observed by Charles Darwin on his quest to developing the Theory of Evolution in the Galapagos Islands

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Species' Potential to Increase in Number

During Charles Darwin's time in the Galapagos Islands, he came across many observations that led him to form the Theory of Evolution. On of the postulate's from this theory is that species have the potential to increase in number. This postulate came from Darwin's observation in which he realized that all species have potential fertility and this characteristic would cause their population size to increase exponentially given the case that all organisms of the given species go on to reproduce successfully. In addition, given the case that resource availability is unlimited, the population of that species has the potential to increase exponentially and therefore increase in number as concluded by Darwin's observations when developing the theory of natural selection. Although the idea of having unlimited resources is idealistic and quite frankly hard to attain, the mere idea of this observation supports the postulate that species have the potential to increase in number.

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heritable genetic variation due to mutation and sexual reproduction

Genetic variation, also known as the variation in alleles of genes of populations, is mainly caused by mutation and sexual reproduction and is essential for natural selection. This postulate relates to evolution because genetic variation allows individuals to adapt to changes in the environment and therefore, survive longer and evolve. So when in the Galapagos, Darwin observed that the characteristics of individuals within a population varied , therefore no two individuals are the same, and these characteristics impact their ability to survive and reproduce. Along with that information, Darwin observed that the observed variation was genetic and because it is genetic, it is heritable.

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competition for limited resources

Some resources are vital to survival, and sometimes these resources are limited. Therefore, when resources that are limited and are needed in order to survive will generate competition between populations. Those who are successful, will survive and produce offspring whereas those who are not, will likely die and fail to produce offspring. Therefore, competition of limited resources helps determine who survives and continues to evolve. Darwin came to this conclusion when he realized that environmental resources, such as shelter and food, are limited. Therefore he inferred that because of the limited resources, some individuals will struggle to survive and only about a fraction of offspring will survive each generation and go on to reproduce.

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proliferation of organisms that are better able to survive and reproduce in the environment

Logically, there will be a rapid increase in number in organisms that are better able to survive and reproduce in the environment. But, to back this up, we look at the idea of biological fitness. Individuals that are biologically fit will reproduce offspring that is more likely to survive and then reproduce again because of it heritable genetic variations. This idea works as a chain reaction, so as an organism evolves to become "fitter" it will help make the next generation stronger and more likely to reproduce successfully and therefore leading up to proliferation.
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SOURCES

Boundless. (2016, January 8). Genetic Variation. Retrieved April 05, 2016, from https://www.boundless.com/biology/textbooks/1514/the-evolution-of-populations-19/population-genetics-131/genetic-variation-530-12943/


Massey University. (n.d.). Darwin's Theory of Evolution. Retrieved April 05, 2016, from http://www.massey.ac.nz/~wwpapajl/evolution/assign2/NM/darwinth.htm


Northwestern University. (2014). Competition for Limited Resources. Retrieved April 5, 2016, from http://modelsim.tech.northwestern.edu/readings/popbio/PopBio-Reading3.1-Competiton for Resources.pdf