Rarefaction analysis of CRISPR spacers in the saliva of human subjects at each sampled time point. Rarefaction curves were created using 10,000 random iterations based on spacer richness. (A) Subject #1; (B) subject #2; (C) subject #3; (D) subject #4. (Open circle) Month −6; (open square) Month −3; (closed triangle) Day 1; (closed square) Day 30; (closed circle) Day 60; (open triangle) Month 11.