Definition: Given a scientific passage and an answer, generate a question for the given answer.
Input: Passage: The rate of evolution depends on how many of an organism's genes have changed over a period of time. Evolution is usually so gradual that we do not see the change for many, many generations. The rate of evolution also depends on the generation time of a particular species. Answer: evolution
Output:
The rate of what process depends on how many of an organism's genes have changed over a period of time and on the generation time of a particular species?