Figure 4. Hawaiian NEEs without SMM silencer elements are enriched in MSR content relative to Non-Hawaiians.

Graph plots the MSR content in the 400Figure 3. The points for the “pure” NEEs, which lack Shnurri/Mad/Medea Silence Elements (SMMSE) are plotted separately from the vnd NEE, which contains a highly conserved SMMSE [19]. NEEs for Hawaiians and non-Hawaiians are plotted separately for ease of comparison. The vnd NEE activity is the least variable in output both ontogenetically and phylogenetically [4]. Its highly constrained early ventral expression is fundamentally important for correct D/V patterning of the nervous system and is thus not likely to be subject to shifting selection for a change in stripe width as we previously demonstrated [19]. Assuming that MSR is a signature of previous selection for changes in threshold responses, these results support the view that MSR content is uniquely enriched in enhancers subject to dynamic evolutionary pressures. Note that the length of the SMMSE that is not also MSR-like is 14 bp (19 bp minus 5 bp because of the underlined sequence in the SMMSE motif: 5′-MYGGCGWCACACTGTCTGS.) Thus, the presence of an SMMSE can only account for a reduction of MSR content of no more than 3.5%.