Distribution of mean normalized Colless’ indices.

Each label represents the mean index of a virus or virus clade. The vertical axis is used to elucidate the clustering of points by forcing overlapping labels (phylogenies with similar indices) to ‘pile up’ like a histogram. A higher Colless’ index corresponds to a less ‘balanced’ tree in which branching events tend to occur along the same lineage. A conventional histogram is displayed in the background. Labels are defined as follows: AstV = astrovirus; CCHF = Crimean-Congo hemorrhagic fever virus; ChikV = chikungunya virus; CA24v = coxsackievirus A24; DEN = dengue virus; E30 = echovirus 30; EMCV = encephalomyocarditis virus; EV71 = enterovirus 71; GBVC = GB virus C; HTNV = Hantaan virus; H[A-E]V = hepatitis [A-E] virus; HIV = human immunodeficiency virus type 1; I[A-C]V = influenza [A-C] virus; JEV = Japanese encephalitis virus; MeV = measles virus; MuV = mumps virus; MVEV = Murray valley encephalitis virus; NV = Norwalk virus; OROV = Oropouche virus; hPIV-1 = human parainfluenza virus; PV = poliovirus; Rab = rabies virus; Rot = human rotavirus; RhiV = human rhinovirus; RSV = human respiratory syncytical virus; Rub = rubella virus; RVF = Rift valley fever virus; SapV = sapovirus; SeoV = Seoul virus; TBEV = tick-borne encephalitis virus; WNV = West Nile virus; YFV = yellow fever virus.