The key difference between founder effect and genetic drift is that a founder effect is an event of genetic drift in which a small group splits from the main population to establish a colony while genetic drift refers to the random changes of allele frequencies in small populations which cause the disappearance of particular genes with time.
Evolution is the process that explains the changing of traits in organisms over successive generations. Evolution relies on natural selection and genetic drift. Due to natural selection, favorable characteristics remain in the populations while unfavorable characteristics diminish from the populations over time. Similarly, genetic drift causes random changes in allele frequencies in small populations, owing to the chance disappearance of particular genes due to dying or avoiding reproduction. Founder effect and bottleneck effect are two events of genetic drift.
CONTENTS
1. Overview and Key Difference
2. What is Founder Effect
3. What is Genetic Drift
4. Similarities Between Founder Effect and Genetic Drift
5. Side by Side Comparison – Founder Effect vs Genetic Drift in Tabular Form
6. Summary
What is Founder Effect?
The founder effect is one of the events of genetic drift that takes place due to colonization. It occurs when a small group splits off from the main population to establish a colony.
Figure 01: Founder Effect
When breaking off from the original population, the new group may contain different allele frequencies than the original population. So the new colony does not represent the full genetic diversity of the original population. Some variants may be completely absent in the established colony.
What is Genetic Drift?
Genetic drift is a phenomenon which is much more likely to occur in small populations and more unlikely to occur in large populations. Basically, it occurs due to random changes in allele frequencies. These could lead to the disappearance of some genes from small populations due to dying or not carrying out reproduction. Ultimately, genetic drift causes less genetic diversity and variation in populations. Moreover, it causes the disappearance of some gene variants completely from the populations. It can also cause some rare alleles to become more frequent than before and even fixed.
Figure 02: Genetic Drift
Genetic drift is of two types: bottle neck effect and founder effect. They cause extreme reductions in populations. Bottle neck effect occurs when the population contracts significantly into a smaller size. It can occur due to natural disasters such as earthquakes, floods, fires. In contrast, the founder effect occurs when a small group in a population splinters off from the original population and forms a new one.
What are the Similarities Between Founder Effect and Genetic Drift?
- The founder effect is an extreme example of genetic drift.
- Both founder effect and genetic drift are more likely to occur in small populations.
- Both change allele frequencies by chance.
- They reduce genetic diversity.
- Some alleles completely disappear from the populations due to both phenomena.
- They can cause the loss of a beneficial allele or fixation of a harmful allele in a population.
- But both are evolutionary important.
What is the Difference Between Founder Effect and Genetic Drift?
The founder effect is an extreme example of genetic drift. It occurs when a small group splits off from the main population and makes a new colony. Genetic drift refers to the change in allele frequency over generations due to chance. So, this is the key difference between founder effect and genetic drift. Moreover, the founder effect is mainly due to colonization, while genetic drift can be due to colonization as well as natural disasters.
Summary – Founder Effect vs Genetic Drift
Genetic drift is a mechanism in evolution that causes random changes in allele frequencies of a small population over time. There are two major effects of genetic drift. One is the founder effect. The founder effect occurs when a small group splits off from the main population to colonize. Due to breaks off from the main population, newly established colony shows different allele frequency and the reduced diversity. So, this summarizes the difference between founder effect and genetic drift.
Reference:
1. “Genetic Drift.” Khan Academy, Khan Academy, Available here.
2. “Genetic Drift.” Wikipedia, Wikimedia Foundation, 18 Aug. 2019, Available here.
Image Courtesy:
1. “Founder effect with drift” By Professor marginalia – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Random sampling genetic drift.” By Gringer – Own work (CC BY-SA 3.0) via Commons Wikimedia