Mapping mutations between segments in the presence of reassortments.

<p><b>(A)</b> Individual toy phylogenies for segments 1 (left) and 2 (right) with respective mutations. <b>(B)</b> Segment 1 phylogeny with segment 2 “background” mutations mapped onto it (left) and segment 2 phylogeny with segment 1 “background” mutations mapped onto it (right). <i>a–d</i>, leaf nodes; <i>e–g</i>, internal nodes; <i>h</i>, virtual node arising due to the reassortment event; <i>r</i>, root node; nodes corresponding to the two segments of the same isolate are denoted with the same letter. Each mutation is identified by a roman numeral and a unique symbol colored according to the segment in which it occurred. Mutation <i>ii</i> in segment 2 maps onto two branches of the segment 1 phylogeny, once as a regular mutation onto branch <i>ra</i> and once as a virtual mutation (denoted by parentheses) onto branch <i>fh</i>.