Homework Help: Questions and Answers: How does genetic drift affect allele frequencies?
a) It increases the frequencies of beneficial alleles that are not heritable.
b) It eliminates all new mutations.
c) The number of generations is takes for an allele to be lost or fixed depends on population size.
d) The number of generations is takes for an allele to be lost or fixed depends on the fitness of the individuals.
Answer:
First, let’s understand what genetic drift is:
Genetic drift is a mechanism of evolution that involves random fluctuations in allele frequencies within a population. These changes are more pronounced in small populations and can lead to the loss or fixation (when the allele frequency becomes 0% or 100%) of alleles purely by chance, regardless of whether the alleles are beneficial, neutral, or harmful.
Given Options: Step by Step Answering
a) It increases the frequencies of beneficial alleles that are not heritable.
- This statement is incorrect because genetic drift is a random process and does not preferentially increase the frequencies of beneficial alleles. Also, if an allele is not heritable, it cannot be passed on to the next generation, so genetic drift wouldn’t affect it.
b) It eliminates all new mutations.
- This is incorrect because genetic drift does not necessarily eliminate all new mutations. Some new mutations might be lost, but others might randomly increase in frequency or even become fixed.
c) The number of generations it takes for an allele to be lost or fixed depends on population size.
- This statement is correct. In smaller populations, genetic drift has a stronger effect, meaning that alleles can become fixed or lost more quickly. In larger populations, this process takes longer because the random effects of genetic drift are diluted.
d) The number of generations it takes for an allele to be lost or fixed depends on the fitness of the individuals.
- This statement is incorrect in the context of genetic drift. Genetic drift is independent of an individual’s fitness. It is a random process, unlike natural selection, which does depend on fitness.
Final Answer
Based on the above analysis, the correct answer is:
c) The number of generations it takes for an allele to be lost or fixed depends on population size
This is because genetic drift has a stronger effect in smaller populations. In smaller populations, random changes can have a more significant impact on allele frequencies, leading to faster fixation (when an allele reaches 100% frequency) or loss (when an allele reaches 0% frequency) of alleles.
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