Search pipeline for Drosophila smORFs. Diagram of the smORF search pipeline followed in this study. The percentages of smORFs passing each filter are indicated. For full details, see Results and Materials and methods. CDS, coding DNA sequence; Dm, Drosophila melanogaster; Dp, Drosophila pseudoobscura; Ka/Ks, ratio of non-synonymous (Ka) to synonymous (Ks) nucleotide substitution.