See the explanation below.
Work Step by Step
There are three hypotheses that are proposed to explain the rate of evolution. The first one is the efficiency-of-repair that states that efficiency of repair of DNA damage will differ in different lineages. It also states that the species with highly efficient repair of DNA damage will reduce the fraction of damage events that lead to mutation. The second hypothesis is that the generation time will vary through natural selection. And lastly, there is the metabolic rate hypothesis which suggests that a high rate of evolution is due to the high metabolic rate of the species.