lmao i forgot to copy paste the entire question, i really should have re-read what i wrote,
sorry bout that,
here is the question!
A student argued that the allele for the dominant dark phenotype in moths could be wiped out more easily in unpolluted forests than the allele for the recessive light phenotype in polluted forests because of the fact that the dominant allele always shows up when it is present in an individuals genotype. Do you agree or disagree? Explain why you think so.
the question is to do with the moths during the industrial revolution and how the white moths were getting wiped out due to pollution- making them more visible etc.
if the question still doesnt make sense and you need more context to it, please let me know!
thank you so much
Hi Kanye,
I think the best way to explain this question is to write out the two different conditions in terms of genotypes and phenotypes.
first up let's assign alleles as D= dark and d= light (for moth colour).
Condition 1: polluted forest (trees will be dark in colour due to pollution).
moths that are DD will be dark, will blend in with the trees and therefore are less likely to be eaten
moths that are Dd will be dark and again, will be less likely to be eaten
moths that are dd will be light, won't blend in and are more likely to be eaten
Condition 2: unpolluted forest (trees will be light in colour)
moths that are DD will be dark, won't blend in and are more likely to be eaten
moths that are Dd will be dark, won't blend in and are more likely to be eaten
moths that are dd will be light, will blend into the trees and are less likely to be eaten
Now let's compare the two situations. You can see that in an unpolluted forest, because the D allele is dominant and is therefore expressed in both the homozygote and heterozygote the D allele is always going to be selected against, whereas in the polluted forest the light phenotype is only seen when the moth is homozygous recessive (dd). The moths that have the genotype Dd will be dark, and therefore less likely to be selected against. This means that the light allele (d) is only selected against in the homozygote not
both the heterozygote and homozygote as seen in the previous condition. Essentially in the polluted forrest, the D allele masks/protects the d allele in the heterozygote so it is more likely to remain in the population.
(Therefore I'd agree with the student).
Sorry for the long-winded answer, I hope that helps!