Evolution and biogeography of Plectocephalus

Evolution and biogeography of Plectocephalus

The genus Plectocephalus comprises a single species in Ethiopia, two in North America and possibly four more in South America, in a striking disjunction that is exceptional for genera of the tribe Cardueae. Susanna et al. investigate the phylogeny and interpret the distribution as a migration via Siberia and the Bering Land Bridge in the late Miocene. Use of plastid markers reveals that previous phylogenies of Centaureinae based on nuclear ITS were flawed by the inconsistent response of the ITS to differences in mutation rates between annuals and perennials.