Estimation of the most parsimonious scenario of evolution in a multifurcated tree. (a) At internal nodes having more than two children, we insert two tentative nodes, τiand τn. We assume that children of τi(τn) always (do not) inherit the target gene from τi(τn). (b) Description of our modification for multifurcated branching (see Materials and methods). (c) It is assumed that the gene is lost in τnwhen the gene is inherited from v. (d) It is assumed that the gene is gained in τiwhen the gene is not inherited from v.