Is Oryx and Crake a sequel?

I'm curious, is Oryx and Crake a sequel to an existing work of literature? I've heard great things about this novel, but I'm unsure if it stands alone or if it's part of a larger series. Could you clarify this for me? I'd appreciate any information you can provide on the book's origins and whether or not it's connected to other stories. Thank you in advance for your help.