Question

Understanding molecular clocks: Select factors that contribute to the nonlinearity of molecular clocks when comparing different species. Check all that apply.

A) Mutation rates may vary between species.

B) Environmental factors have a consistent impact on molecular clocks.

C) Selection pressures can influence the rate of molecular evolution.

D) All species have identical generation times.

Answer 1

Mutation rates and selection pressures contribute to the nonlinearity of molecular clocks, as these factors vary between species and influence the rate at which mutations are accumulated and retained. The correct options are (A) and (C).

Step-by-step explanation:

The factors that contribute to the nonlinearity of molecular clocks when comparing different species include:

• A) Mutation rates may vary between species. Different organisms have different rates of mutation, which can cause discrepancies in molecular clock estimates.
• C) Selection pressures can influence the rate of molecular evolution. Natural selection can act differently on various species, leading to different rates at which mutations are retained or discarded.

Option B is incorrect because environmental factors do not have a consistent impact on molecular clocks — they are variable and species-specific.

Option D is not a contributing factor because species do not have identical generation times; this is a significant variable that affects molecular clocks, as life spans and reproductive rates differ among organisms.