There and back again: switching between host orders by avian body lice (Ischnocera: Goniodidae)

Studies of major switches by parasites between highly divergent host lineages are important for understanding new opportunities for parasite diversification. One such major host switch is inferred for avian feather lice (Ischnocera) in the family Goniodidae, which parasitize two distantly-related groups of birds: Galliformes (pheasants, quail, partridges, etc.) and Columbiformes (pigeons and doves). Although there have been several cophylogenetic studies of lice at the species level, few studies have focused on such broad evolutionary patterns and major host-switching events. Using a phylogeny based on DNA sequences for goniodid feather lice, we investigated the direction of this major host switch. Unexpectedly, we found that goniodid feather lice have switched host orders, not just once, but twice. A primary host switch occurred from Galliformes to Columbiformes, leading to a large radiation of columbiform body lice. Subsequently, there was also a host switch from Columbiformes back to Galliformes, specifically to megapodes in the Papua–Australasian region. The results of the present study further reveal that, although morphologically diagnosable lineages are supported by molecular data, many of the existing genera are not monophyletic and a revision of generic limits is needed