The graphs below show the frequency of the b+ allele over twenty generations in two populations of heterozygous flour beetles (data for a population of ten individuals is shown in graph A; data for a population of one hundred individuals is shown in graph B).Why does the frequency of the b+ allele increase in both populations?
A)b+ is a lethal allele
B)b+ is a balanced polymorphism
C)b+ is a fixed allele
D)the b+ allele is adaptive
E)b+ is a neutral mutation

Question

The graphs below show the frequency of the b+ allele over twenty generations in two populations of heterozygous flour beetles (data for a population of ten individuals is shown in graph A; data for a population of one hundred individuals is shown in graph B).Why does the frequency of the b+ allele increase in both populations? 
A)b+ is a lethal allele 
B)b+ is a balanced polymorphism 
C)b+ is a fixed allele 
D)the b+ allele is adaptive 
E)b+ is a neutral mutation

Quizplus · Accepted Answer

The frequency of the b+ allele increases in both populations, indicating that it is adaptive. This means that individuals carrying this allele have a higher fitness and are favored by natural selection, causing the frequency to increase over time. If the b+ allele was lethal (A) or neutral (E), it would not increase in frequency. If it was a balanced polymorphism (B), then both the b+ and b- alleles would be maintained at a stable frequency. If it was a fixed allele (C), then there would be no change in frequency over time.

The Graphs Below Show the Frequency of the B+ Allele