User:Jheald/scratch
in molecular biology molecular coevolution occurs when a mutation at one position in a biological sequence causes selection pressure at another position, and vice-versa reciprocally.
For example, if a folded protein structure requires two amino acid residues to be in close proximity with each other, as illustrated in the image on the right, then any mutation that affects one of the residues may make any subsequent mutation that affects the other in a compensatory way highly advantageous, to preserve the structure.