Morph B Dominance Explained
This question relates to population genetics, specifically the effect of mutation rates on the relative abundance of different morphs (forms) within a population.
Mutation Dynamics
We have two morphs, A and B, in a population. They mutate between each other:
- Morph A mutates to Morph B with probability $p_1$.
- Morph B mutates to Morph A with probability $p_2$.
The problem states that $p_1 \gg p_2$, meaning the mutation rate from A to B is significantly higher than the mutation rate from B to A.
Analysis of Morph Frequencies
Although both morphs reproduce at equal rates, the mutation process continuously converts morphs from one form to another.
- The forward mutation (A to B) occurs at a high rate ($p_1$).
- The reverse mutation (B to A) occurs at a very low rate ($p_2$).
This results in a net flow of individuals from morph A to morph B over time. The high rate of A converting to B, coupled with the low rate of B converting back to A, creates a strong 'mutation pressure' favoring morph B.
Conclusion
Because there is a constant and strong net conversion of morph A into morph B, morph B will tend to increase in frequency relative to morph A. Therefore, over time, Morph B will dominate the population.
Important Questions from Mutation
- Which one of the following mechanisms is expected to generate tightly linked genes?
- A gene coding for a particular protein exhibits 2% DNA sequence divergence between humans and chimpanzees. However, protein sequences encoded by them are identical. Which one of the following processes explains this?
- Gene conversion can lead to which one or more of the following evolutionary outcomes?
- For a given gene there is 5% DNA sequence divergence between two species, however the protein coded by this gene has identical sequences in the two species. Which of the following types of mutations best explains this pattern in the DNA sequence?
- Following a gene duplication event, the duplicated copy often loses function and is called a pseudogene. In the absence of positive selection, which of the following is true about these genes?
