Distribution of mapped 454 reads with respect to AT content. The genomic reads were mapped to the Amel_4.5 assembly (scaffolds and contigs) using BLAT. With relatively stringent filtering (at least 80% of total length matched and gap size < 30%), 242,284 reads (93% of all reads) were aligned to the assembly. Most reads (236,090, 93%) aligned to fewer than 10 locations, and had unique alignments (210,625, 87%). The AT content for each alignment (adding 10% extension on either end) was calculated for reads with ≤ 10 match locations.