Figure 1.
Intron size for Homo sapiens (a), Arabidopis thaliana (b), Drosophila melanogaster(c), and Caenorhabditis elegans (d). There is always a species-specific minimum intron size, at which a significant fraction of the introns tend to cluster. This “spike” in the distribution is centered around the mean (±SD) intron sizes of 92±14, 89±12, 61±10, and 48±9 bp, respectively. For larger introns, the size distribution is highly species-specific. In the extreme case,H. sapiens, there is a broad “hump” attributable to transposon insertions inside the introns. Color indicates GC content: Red is GC-rich; blue, AT-rich.
