2. Consider a new mutant arising in a finite population. a. Compare the length o
ID: 161552 • Letter: 2
Question
2. Consider a new mutant arising in a finite population.
a. Compare the length of time required to fix or lose this new mutation by selection vs.
genetic drift.
-> Selection is generally faster than drift, even when weak.
b. How does your answer help explain why most polymorphisms are selectively
neutral?
-> Since mutations under selection are resolved quickly, few contribute to standing
variation. The only ones that remain at intermediate frequencies are those that are
selectively neutral.
Could you explain the answers to these questions to me a little clearer? It seems to me the natural selection should occur at a slower rate than drift, but this is not the case.
Explanation / Answer
a) 1. If frequency of traits in a population changed purely by chance, then the genetic drift occurs.
2. Natural selection is the process by which most adaptive traits for an environment are passed generation after generation.
3. Natural selection is not random process and purposeful process.
4. According to theory of evolution, polymorphism results from evolutionary process. It is heritable and modified by natural selection.
5. Genetic makeup determines the morphs,
6. Genetic polymorphism is actively steadily maintained in population by natural selection.
b) 1. Rate of increase in fitness of any organism is equal to its genetic variance.
2. It means that natural selection acting through changes in gene frequencies, which is exactly equal to its genetic variation in fitness at that time.
3. Evolution due to genetic drift is not caused by environmental or other kinds of stress. The resulting random changes can be detrimental, neutral, or beneficial the reproductive generation.
4. Genetic drift working in small populations can be quickly result in big changes, where as in large population effects are minor compared to the entire gene pool and often overshadowed by natural selection.
5. Because of the above reason genetic drift is slower rate than the natural selection.
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