A. When a mutation arises, it can have three possible consequences: beneficial to the individual, selectively neutral, or detrimental. Order these from most likely to least likely

Question

B. The spread of a mutation in subsequent generations will, of course, depend on its consequences to individuals that inherit it. Order the three possibilities in part A to indicate which is most likely to spread and become overrepresented in subsequent generations, and which is most likely to become underrepresented or disappear from the population.

Answer 1

A. The order is selectively neutral, detrimental, beneficial. Most nucleotide changes in the genome, or mutations, will have little or no effect on the fitness of the individual because many changes are not located in regions that encode a protein or regulate the expression of a gene. Even changes within a coding region may not change the amino acid encoded or may cause a conservative amino acid change—for example, from one small nonpolar amino acid to another. Most changes that have a functional consequence will interfere with the regulation of a gene or the behavior of the encoded protein, usually rendering it useless and occasionally making it harmful or yielding a new function. Only very rarely will a mutation improve the performance of the gene or its encoded protein.
B. The order is beneficial, selectively neutral, detrimental. Individuals bearing beneficial mutations will be more likely to have more offspring than others in the population, and thus the beneficial mutations will become overrepresented in the population in subsequent generations. Individuals bearing detrimental mutations will be likely to have fewer children and grandchildren, and thus these mutations will be culled from the population, although perhaps not eliminated.