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Charles Darwin, also known as the ‘father of evolution,’ coined the term Darwinism: the theory stating the evolution of a species is determined by survival of the fittest and natural selection. For those unaware, natural selection is the process in which organisms with specific traits better suited for their environment are more likely to survive and reproduce. While Darwin’s theory was revolutionary, another important contributing factor to the evolution of all species is genetic drift.

Genetic drift is the random change in a frequency of traits over a period of time due to occurrences of chance events. For instance, if a lightning storm eviscerated a black bird population in a group of blue and black birds, the following generations would primarily consist of birds with the blue gene. These ‘chance events’ can lead to drastic consequences (both negative and positive) in the timeline that is evolution.

There are two main types of genetic drift; the bottleneck effect and the founder effect. The bottleneck effect, the loss of a large portion of a population due to an environmental event, can be represented in the case of the Great Tohoku Earthquake. In 2011, the Great Tohoku Earthquake in Japan wiped out four of the six Carex rugulosa plant species. This loss of a large portion of the C. regulosa plant species is a great example of the bottleneck effect, illustrating the result of a natural disaster on a population.

The founder effect, a phenomenon where a new population is established by a small group of individuals from a larger one, can be represented in the increased likelihood of Ellis van Creveld syndrome (a.k.a. dwarf syndrome) in the Old Order Amish of Pennsylvania. After a group of Amish separated from their original community, the genes of the ‘founders’ of this specific Amish population became disproportionally frequent in the offspring due to their tendency to marry within the group. The Ellis van Creveld gene, prevalent in one of the Amish group’s founders, spread throughout the community, increasing the likelihood of inheriting dwarf syndrome. Along with similar genetic sequences, the founder effect results in a higher frequency of certain traits as well as genetic diseases in the new population compared to the original population. The founder effect explains why the Amish population of Pennsylvania has a greater prevalence of Ellis van Creveld syndrome compared to the general population.

These examples are several of the many genetic drift occurrences that have shaped our evolutionary history. Genetic drift and natural selection have worked together throughout history to form the world we live in today, from population extinctions to genetic mutations. Shaped by random events and environment pressures, these forces continue to influence the evolution of species. Even the smallest change can have lasting effects, prompting the question: How does genetic drift, driven by chance, change species?