Which statement regarding mutation rates and evolution is true?

Mutation rates are a critical aspect of the evolutionary process, influencing how quickly a population can adapt to changes in its environment. Each of the statements provided reflects an important facet of the relationship between mutation rates and evolution.

Mutation rates indeed have a strong effect on the rate of evolution. Higher mutation rates can lead to a greater variety of genetic variations for natural selection to act upon, potentially accelerating evolutionary change. The introduction of beneficial mutations can lead to rapid adaptations, while deleterious mutations can be purged from the population.

Most mutations are either neutral or deleterious. This is understood through the concept of the neutral theory of molecular evolution, which suggests that many mutations do not confer any significant advantage or disadvantage to an organism and therefore accumulate in a population over time due to genetic drift. Even when mutations are deleterious, they can persist for a while, especially in large populations where selection pressure may not immediately eliminate them.

Larger populations generally evolve lower mutation rates because they have more stable environments and higher effective population sizes. This stability allows them to experience sufficient genetic diversity without requiring higher mutation rates, which can be harmful over time. Additionally, in larger populations, the probability that a deleterious mutation becomes fixed is lower, which may lead to a