Figure 2

Intronic densities for the main classes of repetitive elements. (a) Primate specific, (b) mammalian specific and (c) vertebrate and older. At each intronic position, the density was calculated as the proportion of cases in which the base was covered by a given type of repetitive element. We give on the x-axis the relative position from the splice junctions as negative if upstream of the acceptor site or positive if downstream of the donor site.