Causes Of Genetic Drift

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Steven Cheng Final Copy

Scientific explanations are evaluated using evidence from the natural world. By performing experiments, science is a process that uses data and evidence to explain the evolutionary process. There is Constancy and Change in Natural Systems that can be, understood by recognizing patterns and explained through mathematics. As we discussed in class “Science can be considered a form of conceptual evolution where natural selection insures the survival of the fittest ideas”. Those 3 ingredients are heritability, variation and differential success. In order for selection to occur three main criteria’s are necessary in order for a specie to prosper and survive. Without these ingredients a species will have little to no chance
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Genetic drift affects the genetic makeup of the population but, unlike natural selection, through an entirely random process. So although genetic drift is a mechanism of evolution, it doesn’t work to produce adaptation. This phenomenon are the result of two different causes, the bottleneck and the founder effect. The bottleneck is mostly due to catastrophic environmental events and or human causes like hunting. Which result in a certain species population to become very small, which results in less variation because there are not as many organisms to mate with. This happened to the American bison in the 18th century, when hunting the bison became more popular for their fur and meat, as well as becoming a “sport” for hunting enthusiast around the world. The population of the bison’s by the end of the 19th century went from being in the millions to hundreds. Because of the dramatic decrease in population most of the bison today are genetically very similar because the smaller the population many alleles are lost forever. The founder effect is seen when a small group of a certain species leave their original environment and set up a new colony elsewhere. An example of this occurrence, was the one discussed in class. Involving lizards being taken from their natural habitat to an isolated island. The result of this was a change in genetic makeup for the lizards on the isolated island. They eventually developed shorter hind limbs because it was adaptive to the new environment. Also, because only a handful of lizard were taken to the island, variation was not

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