The solution to the puzzle of why the rate of substitution is approximately constant per year, despite drastic differences in generation time among species, relies on the
A) relationship between the strength of selection and the number of new mutations.
B) inverse relationship between generation time and population size.
C) effect of neutral mutations on generation time.
D) number of new mutations that experience heterozygote advantage.

Question

Quizplus · Accepted Answer

The solution to the puzzle lies in the inverse relationship between generation time and population size. Species with shorter generation times tend to have larger population sizes, which results in more opportunities for mutations to occur per unit of time. Conversely, species with longer generation times usually have smaller population sizes, leading to fewer mutations per unit of time. This inverse relationship helps to balance the rate of substitution across species with different generation times, making it approximately constant per year.

The Solution to the Puzzle of Why the Rate of Substitution