Ameliorate Darwinism

Directions: Please grammatically correct this sentence. There are three missing commas and one missing apostrophe.

Darwinism is a theory of biological evolution stating that all species of organisms arise and develop through the natural selection of small inherited variations that increase the individuals ability to compete survive and reproduce.

LINK
suggested Answer:
Darwinism is a theory of biological evolution stating that all species of organisms arise and develop through the natural selection of small, inherited variations that increase the individual's ability to compete, survive, and reproduce.