Figure 2
From: Jane: a new tool for the cophylogeny reconstruction problem
(a) Strongly incompatible host switching events. Parasite a on edge (u, w) switches to child b on edge (t, v) implying that v occurs after u. Similarly, parasite c on edge (v, y) switches to child d on edge (t, u) implying that u occurs before v. This results in an irreconcilable timing conflict. (b) Weakly incompatible host switching events. Parasite a on edge (t, v) switches to child b on edge (u, w) implying that a occurs after u and thus after c. Similarly, parasite c on edge (t, u) switches to child d on edge (v, z) implying that c occurs after v and thus after a. (c) This conflict can be resolved, for example, by moving one of the landing sites of a host switch earlier in time, incurring an additional loss event at u.