The percentage (%) of the alleles that code for this trait in the population will increase, as more individuals are born with the trait.
Explanation:
The more individuals get born expressing the trait, the higher its frequency gets in the population. By generation, there are more individuals carrying the allele for the advantageous trait. These individuals reproduce and increase the probabilities of the progeny to inherit the mentioned allele. When this sequence keeps occurring in the population over many generations, the allele percentage will increase. On the other hand, the other allele or alleles will decrease. Probably, if there are no changes that might influence or affect this pattern, the alleles for the advantageous trait will fixate, while the other allele might get lost.
