Knock-in at the Atpα locus that does not introduce any non-synonymous changes and therefore acts as an engineered control. It is designated 'QAN', referring to overall Atpα genotype at three amino acid sites (111, 119 and 122) in the orthologous gene of the monarch butterfly (Danaus plexippus) that repeatedly changed in the mutational path of that gene in its evolution of a specialized response to cardiac glycosides. (Amino acid residues are numbered after the mature Sus scrofa protein, as in previous phylogenetic studies of Atp-alpha in insects.)