How does the founder effect cause genetic drift?

The founder effect causes genetic drift by reducing genetic variation when a small group splits off from a larger population.

The founder effect is a type of genetic drift that occurs when a small group of individuals breaks away from a larger population to establish a new population. This small group may not represent the full genetic diversity of the original population, leading to a reduction in genetic variation. This is because the founders of the new population carry only a small sample of the genetic diversity present in the original population.

Genetic drift is a mechanism of evolution that involves changes in allele frequencies in a population over time, due to random chance. In the context of the founder effect, the allele frequencies in the new population are likely to be different from those in the original population, simply because the founders represent a random sample. Over time, these differences can become more pronounced, especially if the new population remains isolated.

The founder effect can have significant impacts on the genetic diversity and evolutionary trajectory of a population. For instance, if the founders carry a rare allele, that allele could become much more common in the new population than it was in the original population. Conversely, if the founders do not carry a particular allele, that allele could be absent from the new population altogether.

In addition, the founder effect can lead to increased genetic drift if the new population remains small. This is because in small populations, random fluctuations in allele frequencies can have a larger impact. Over time, this can lead to the fixation of certain alleles (where all individuals in the population carry the same allele) and the loss of others, further reducing genetic diversity.

In summary, the founder effect causes genetic drift by initiating a new population with a limited and random sample of the genetic diversity of the original population. This can lead to changes in allele frequencies and reduced genetic diversity, especially if the new population remains small and isolated.