Conservation and divergence of BEAF-32 sites in Drosophila species. (A) Distribution of BEAF-32 binding sites with respect to various gene landmarks. (B) Percentage of various gene pair combinations flanking BEAF-32 binding sites; (ht) head-to-tail; (hh) head-to-head; (tt) tail-to-tail; (th) tail-to-head. BEAF-32 association with head-to-head gene pairs is conserved. (C) Consensus motif for BEAF-32 occupied sequences in the four species. (D) Correlation of BEAF-32 binding divergence with evolutionary distance between D. melanogaster and other species. (Y-axis) Percentage of BEAF-32 binding sites that are not conserved in the other three species with respect to all BEAF-32 binding sites in D. melanogaster. (E,F) Species-specific loss of BEAF-32 binding associates with species-specific loss of the BEAF-32 motif in the DNA sequence. (Dark blue bars) Background absence of the BEAF-32 motif for all BEAF-32-associated gene pairs in each species. (Light blue bars) Absence of the BEAF-32 motif for a group of gene pairs with BEAF-32 binding lost only in D. pseudoobscura (E) or only in D. virilis (F).
