Frequency distributions of the depths of NGS reads of AS75 mapped to annotated Roche 454 reads. Except that for characterized repeat reads, the remaining distributions can be approximated to an extreme value distribution. (A) Frequency distributions of the depths of AS75 SOLiD genomic reads (total ~ 26X genome equivalents) mapped to Roche 454 characterized gene reads, repeat junction reads, characterized repeat reads, and uncharacterized reads. Because most gene-related reads are single copy, the frequency distribution of reads mapped to gene-related reads is used as single-copy read distribution. The estimated population mean () plus two standard deviations (s) (depth of 53X) of this distribution was used as the cut-off depth for considering AS75 SOLiD genomic reads mapped on Roche 454 AL8/78 gene reads, repeat junctions, and uncharacterized reads as single-copy. (B) Frequency distributions of read depths and + 2s cut-off values for Solexa AS75 genomic reads (~1.56X genome equivalent) and Roche 454 AS75 genomic reads (~0.11X genome equivalent) mapped to characterized gene reads of Roche 454. The distributions were skewed to the left because of low coverage but still could be fitted to an extreme value distribution (a Weibull distribution) .