The fraction of introns containing TEs and their median lengths in non-mammalian and mammalian transcriptomes. (a) The fraction of TE-containing introns within five non-mammalian genomes compared to that of human (Homo sapiens) and mouse (Mus musculus) (for details see Materials and methods). (b) A graph of the median length of introns containing TEs compared to that of introns without TEs (marked in grey and black, respectively) in the different organisms. (c) Positive correlation between median intron length and the fraction of TEs containing introns. Intron lengths were taken from .