Fig. 3

Effects of metatranscriptome size on read abundance variation. As the number of annotations in a metatranscriptome increases along the X axis, accuracy of abundance measurements increases for all reads. Red denotes the top 5 most abundant transcripts within the sampled metatranscriptome (by counts), while blue denotes transcripts of medium abundance (top 50 % by sorted counts) and green denotes low-abundance transcripts (bottom 10 % by sorted counts). Approximately 10–15 million annotations are needed before abundance accuracy for all transcripts tops 90 %. Abundance accuracy was measured out to 20 million annotations, but the accuracy was 100 % in all categories beyond 15 million (data not shown)