Figure 1From: Some novel intron positions in conserved Drosophila genes are caused by intron sliding or tandem duplicationOverview on mechanisms proposed for the emergence of novel intron positions within conserved ORFs. It is commonly assumed that the first mechanism was responsible for the emergence of spliceosomal introns in ancient eukaryotes. More recent intron gains or intron position changes may be caused by the other mechanisms shown.Back to article page