title: On the origin of the woody buckwheat Fagopyrum tibeticum (=Parapteropyrum tibeticum) in the Qinghai-Tibetan Plateau.
abstract: Here we tested whether 'insular woodiness', a striking evolutionary pattern that commonly occurs on islands, has also appeared in QTP continental endemics. Parapteropyrum, a monotypic shrubby genus occurring in the central QTP, has been previously placed in the tribe Atraphaxideae of the family Polygonaceae, while all the other woody species of this tribe mainly occur in western and central Asia. We studied sequence variations of nuclear ITS (internal transcribed spacer) and cp (chloroplast) DNA (rbcL and accD) of this genus and the other ten genera. The constructed phylogenies based on ITS, cpDNA or a combination of both datasets, suggest that the woody Parapteropyrum is nested within and most likely evolved from the herbaceous Fagopyrum. We propose that the large-scale uplift of the QTP not only promoted continental species radiation, but also the secondary feature of woodiness in a few herbaceous lineages in response to strong selection pressures, similar to those acting on island flora. In addition, the confirmation of Parapteropyrum within Fagopyrum highlights its potential use as a new, perennial source of buckwheat.
authors.affiliation: Molecular Ecology Group, Key Laboratory of Arid and Grassland Ecology, Lanzhou University, Lanzhou 730000, Gansu, PR China.
authors.forename: Xinmin
authors.initials: X
authors.lastname: Tian
authors.forename: Jian
authors.initials: J
authors.lastname: Luo
authors.forename: Ailan
authors.initials: A
authors.lastname: Wang
authors.forename: Kangshan
authors.initials: K
authors.lastname: Mao
authors.forename: Jianquan
authors.initials: J
authors.lastname: Liu
mesh_terms: D001209:Asia, Central; D005075:Biological Evolution; D002467:Cell Nucleus / Q000235:genetics; D018742:DNA, Chloroplast / Q000235:genetics; D018744:DNA, Plant / Q000235:genetics; D021903:DNA, Ribosomal Spacer / Q000235:genetics; D019612:Fagopyrum / Q000145:classification* / Q000235:genetics; D010802:Phylogeny; D017422:Sequence Analysis, DNA
chemical_list: D018742:DNA, Chloroplast; D018744:DNA, Plant; D021903:DNA, Ribosomal Spacer