<p>The repetitive elements are represented as black lines in the introns, where other regions are represented as gray spaces. The values along the vertical coordinates represent the numbers of introns (500 introns are selected randomly from the first introns and other introns, respectively). The directions of introns are from 5′-ends to 3′-ends. The nucleotide positions are relative to the splice sites. (A) Repetitive elements in the 5′-ends (left panel) and 3′-ends (right panel) of the first introns. (B) Repetitive elements in the 5′-ends (left panel) and 3′-ends (right panel) of the other introns position. ‘0’ at 5′-end and 3′-end denotes the position of 5′-splice site and 3′-splice site of the introns, respectively.</p
