Evidence for avian genes missing in syntenic blocks. Example of avian missing syntenic block, revealed by local chromosomal alignment of 1-to-1 orthologous genes in lizard, chicken, and humans, based on chromosomal position in lizard (for full set of deletions see Additional file 1: Table S1A). Syntenically ordered genes missing in birds are shaded in orange; flanking genes that are shared by all species including birds (for example, chicken, Tibetan tit) are shaded in blue. The relative position of each individual gene locus is indicated by chromosome number (for example, chr2, 19) and starting base of the corresponding Ensembl gene model. The asterisk indicates a gene with no predicted Ensembl model in lizard; its location was determined by cross-species BLAT-alignment with sequence from the lizard ortholog.