[audio|src:'/listening/toefl-test/76/s4-1.mp3']

[audio|src:'/listening/toefl-test/76/s4-2.mp3']

[audio|src:'/listening/toefl-test/76/s4-3.mp3']

Using the examples of mice and rabbits from the lecture, describe the two different types of factors that can cause population changes.

Prepare time: 20 seconds.