1. Summary

This video explains the two different representations of genetic drift. There are examples provided on how both the bottleneck effect and founders effect play a role in genetic drift. A better understanding is provided how genetic drift and natural selection differ in evolution.

2. Why Watch This Video?

1. Have you ever wondered how genetic drift and natural selection are different in their roles with evolution?
2. Would you like to know how genetic variations play a role in evolution that does not involve natural selection?
3. Have you ever been confused by how the bottleneck and founder effect are involved within genetic drift?

3. Key Terms

Genetic Drift: Changes in gene frequencies of a population due to random events.

Bottleneck Effect: Occurs when natural disaster reduces a populations size.

Founder Effect: When a small group splits off from the main population to start a new colony at a new location.

4. Loose Ends

Loose end #1: The video doesn’t discuss the time frame in which bottleneck theory or founder effect takes to develop. Bottleneck effect can take a generation to develop. Within the video they use short term examples to explain the concept. The founder effect is when a small population from their homeland decides to go colonize a new location. There is no timeline for this effect to fully occur and from their example, it would take roughly a generation or more to develop.

Loose end #2: Genetic Drift has two different representations. Both Bottleneck Effect and Founder Effect have a role of chance that changes the allele frequency in the new population due to effects of different natural events. This is how both these effects are involved in Genetic Drift.

Loose end #3: Genetic Drift is another variation in evolution that may not be as common as natural selection. Both work hand in hand in how organisms have evolved over the generations. Its either one or the other at a given time and not at the same time.

5. Self-Test Questions

Question 1: What is Genetic Drift?
Answer a: Occurs when natural disaster reduces a populations size.
Answer b: When a small group splits off from the main population to start a new colony at a new location
Answer c: When a change in allele frequency occurs due to random events
Answer d: An event occurs and only the best fit survives.

Question 2: When there are bugs on a block of cement and you run over a portion, 1 time with your bike and randomly killing some of them, what is this called?
Answer a: Genetic Drift
Answer b: Natural Selection
Answer c: Allele Frequency
Answer d: Genetic Variety

Question 3: This is the main idea surrounding genetic drift is:
Answer a: random/lucky survival
Answer b: most fit survive
Answer c: 60% females survive
Answer d: every 2nd generation goes through a disaster

Question 4: When 4 out of 30 birds decide to leave their flock and try settling on a new area where their ancestors have never been, what is this called?
Answer a: Bottleneck effect
Answer b: Natural Selection
Answer c: Natural Disaster
Answer d: Founder Effect

Question 5: There are 2 trees with an even amount of birds on each tree. One day lightning strikes one of the trees, it catches fire and the birds on that tree die. The second tree is untouched, and the birds are unharmed. What is this called?
Answer a: Natural Selection
Answer b: Bottleneck Effect
Answer c: Founder Effect
Answer d: Amoeba Drift

6. Answers to Self-Test Questions

1. C. The definition of genetic drift is a change in allele frequency which occurs due to random events.

2. A. Genetic Drift because genetic drift is all about the random and lucky part of evolution unlike natural selection which is survival of the fittest. Allele frequency and genetic variety are all aspects within genetic drift.

3. A. Random/lucky survival because genetic drift is built on the premise that it is a random event that changes the allele frequency.

4. D. Founder effect because the idea surrounding this is a part of the colony splits off and colonizes at a new location. Exactly what these birds are doing.

5. B. Bottleneck effect. The surviving organisms were not better fit to survive on their tree compared to the others. They don’t represent the original population resulting in a new allele frequency in the new population. This is the premise of bottleneck effect.

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Item Credit: Amoeba Sisters

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