An example for exon duplication. Shown is the NIP region of the CG8105 gene (FBgn0030661). Intron sequences are shown in lower case. The amino acid sequence consensus of the CDS is given beneath the exon sequences. While intron 211-0 of D. ananassae has probably risen by exon duplication, the mechanism of origination of intron 214-1 (D. willistoni) remained unknown. Note that the 5' part of the proto-splice site in position 211-0 (highlighted in grey) strongly varies between the species. No other insect species has an intron within this region of the CDS, so both introns are considered novel.