"Would the cycle of life be effected if there was no more domestic pets?"
Well if animals had never been domesticated I think the world would be so much different. Originally animals were domesticated because we needed their help. Dogs were domesticated so they could help protect farm animals that were domesticated for easy hunting. Even know if there were no domesticated animals people would suffer. There would be no guide dogs to help those that need them. And if cats hadn't have been domesticated there would be a very lonely Laura sitting in her apartment all by her lonesome