Phylogeny Orders HSE Evolution Figure 8. Sizes and positions of identified HSEs for all identified copies of Hsp70 in 13 Drosophila species. The number of HSEs is nearly constant across copies in all species. Proximal HSEs are nearly invariant in position, and differ minimally in length. There is a larger amount of variation in the position of distal HSEs, but only a single gain/loss of HSEs occurs, in one copy of Hsp70 from D. santomea. doi:10.1371/journal.pone.0010669.g008 PLoS ONE | www.plosone.org 9 May 2010 | Volume 5 | Issue 5 | e10669