Figure 6. Non-allelic gene conversion spreads refining mutations among TE-derived MSL recognition motifs.
Shared polymorphism of the TT haplotype among ISX insertions suggests a model where a mutation that refines regulatory activity arose once at a single TE-derived regulatory element, and spread across elements via non-allelic gene conversion. Over evolutionary time, such a mutation spreads in two dimensions: horizontally among TE-derived regulatory elements and vertically through the population, until it is fixed across elements and across individuals. The TT haplotype is at the midpoint of this process. Across ISX insertions, it is fixed, absent, and polymorphic, in approximately equal proportions.