Final answer:
Certain alleles become more widespread than others during the natural selection process, altering the population's genetic makeup. Offspring carrying the beneficial allele have a higher chance of survival and reproduction, perpetuating the cycle and spreading the allele throughout the population. Detrimental mutations can be eliminated, while beneficial alleles can become fixed.
Step-by-step explanation:
The allele frequency within a given population can change depending on environmental factors; therefore, certain alleles become more widespread than others during the natural selection process. Natural selection can alter the population's genetic makeup. An example is if a given allele confers a phenotype that allows an individual to better survive or have more offspring. Because many of those offspring will also carry the beneficial allele, and often the corresponding phenotype, they will have more offspring of their own that also carry the allele, thus, perpetuating the cycle. Over time, the allele will spread throughout the population. Some alleles will quickly become fixed in this way, meaning that every individual of the population will carry the allele, while detrimental mutations may be swiftly eliminated if derived from a dominant allele from the gene pool. The gene pool is the sum of all the alleles in a population.