Darwin's Four Factors of Evolution

by: Jose Pablo G

Potential for Population Growth

There are four main variables that determine the population size of a certain species. Birth, death, immigration and emigration are the determinants that can give potential for species to either grow or slowly disappear.

Biotic Potential

- Biotic Potential has to do with the amount of resources available and the environmental conditions present. Each species however has different biotic potentials due to their reproductive span, frequency of reproduction, litter size and survival rate.

Carrying Capacity

- Carrying Capacity on the other hand is the maximum number of a given species a certain area can support. Carrying capacity affects the potential population growth for species because it determines a limit.

Population Impact

- Lastly, population impact is the last affecting variable in the potential for a species to grow. The impact other species have on a given population will determine resources, growth factors and live span.

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Genetic Variation

The role of genetic variation is extremely significant when dealing with natural selection. The ability for a species to transfer genetic information and create several variations in phenotypes will produce some organisms that are better suited for the environment that the species is presented with.

Natural selection does not however create perfectly adaptable organisms, but rather shifting genetic information to create favourable phenotypes that are able to cope with their environments. Another reason why genetic variation does not create perfectly adaptable organisms is because of the allele constraints present in the genetic pool of the species that in essence, maintains a stable allele combination that will never be perfected.

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The ability for an offspring from a given species to compete for limited resources has a lot to do with Darwin's previous claim regarding genetic variation affecting natural selection.

Darwin and Wallace claim that offspring that inherited the modified allele phenotype and had an advantage when competing for the limited resources will in fact survive. Thus, this surviving organisms with "advanced" or stronger inherited genetics will produce offspring that will compete with the less advanced organisms of the same species.

In addition, because the characteristics and traits that are inherited and passed from generation to generation, this will lead to a change in population over several generation which Darwin called "descent with modification".

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Proliferation of Organisms

Variation allows for members of a certain species to reproduce better than others. It there is an organism that is "better equipped" or has a trait that helps them survive, it will be able to reproduce more efficiently and thus, passing the trait to other members. An example of this is with a lion and a gazelle. A very fast lion is able to catch gazelles and survive, but on the other hand, a fast gazelle is able to outrun the lion and survive.
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