title: Cophylogeny of Nosema (Microsporidia: Nosematidae) and bees (Hymenoptera: Apidae) suggests both cospeciation and a host-switch.
abstract: Some microsporidian parasites belonging to the genus Nosema infect bees. Previous phylogenies of these parasites have produced alternative, conflicting relationships. We analyzed separately, and in combination, large and small subunit ribosomal DNA sequences of Nosema species infecting bees under neighbor-joining, maximum parsimony, maximum likelihood, and Bayesian frameworks. We observed a sister relationship between Nosema ceranae and Nosema bombi, with Nosema apis as a basal member to this group. When compared to their respective hosts (Apis cerana, Bombus spp., and A. mellifera), 2 plausible evolutionary scenarios emerged. The first hypothesis involves a common ancestor of N. bombi host-switching from a historical Bombus lineage to A. cerana. The second suggests an ancestral N. ceranae host-switching to a species of Bombus. The reported events offer insight into the evolutionary history of these organisms and may explain host specificity and virulence of Nosema in these economically important insects.
authors.affiliation: Department of Biology, Acadia University, Wolfville, Nova Scotia, Canada, B4P 2R6. shafer@ualberta.ca
authors.forename: Aaron B A
authors.initials: AB
authors.lastname: Shafer
authors.forename: Geoffrey R
authors.initials: GR
authors.lastname: Williams
authors.forename: Dave
authors.initials: D
authors.lastname: Shutler
authors.forename: Richard E L
authors.initials: RE
authors.lastname: Rogers
authors.forename: Donald T
authors.initials: DT
authors.lastname: Stewart
mesh_terms: D000818:Animals; D001499:Bayes Theorem; D001516:Bees / Q000145:classification* / Q000235:genetics / Q000469:parasitology*; D004275:DNA, Ribosomal / Q000737:chemistry; D049810:Genetic Speciation; D016013:Likelihood Functions; D016818:Nosema / Q000145:classification* / Q000235:genetics; D010802:Phylogeny; D012335:RNA, Ribosomal / Q000235:genetics
chemical_list: D004275:DNA, Ribosomal; D012335:RNA, Ribosomal