3 If gene flow were eliminated between northern and southern

3. If gene flow were eliminated between northern and southern portions of the scarlet kingsnake\'s range, what do you predict would happen to the frequency of alleles that produce a coral snake-like pattern as a result of natu- ral selection? a. The frequency of the alleles would increase in the northern part of the range. he frequency of the alleles would decrease in the northern part of the range. c. The frequency of the alleles would increase in the southern part of the range. d. The frequency of the alleles would decrease in the southern part of the range.

Solution

we know that the frequency of the allele= occurence of allele/ total number of alleles.

the best adapted individual survive and give its alleles to the offsprings to be successful in the gene pool.when the populations are small the allelic frequencies can decrease, increase or even get lost by the change. this has nothing to do with the natural selection.

scarlet kingsnakes migrate from southern to the northern parts. if the gene flow is stopped they wont be able to migrate. Scarlet kingsnakes mimic the venomous coral snakes where the ranges of the two species overlap. But farther away from these regions, the kingsnakes look less like the coral snakes. Natural selection favors genes for mimicry in the regions of overlap. Predators that live in the coral snake’s territory learn to avoid the bright color pattern.

but in the above situation when the gene flow is not happening the predators will be picking up from the northern region the coral snake like pattern and even their population will be reduced due to the alleles which are not coming from south anymore. so if there are no ranges of overlap the frequency of alleles in northern range decreases.

hence all the other options are negated as in south portion the frequency of the allele is stable and wont get affected much.