title: Species delimitation in plants using the Qinghai-Tibet Plateau endemic Orinus (Poaceae: Tridentinae) as an example.
abstract: OBJECTIVE
  Accurate identification of species is essential for the majority of biological studies. However, defining species objectively and consistently remains a challenge, especially for plants distributed in remote regions where there is often a lack of sufficient previous specimens. In this study, multiple approaches and lines of evidence were used to determine species boundaries for plants occurring in the Qinghai-Tibet Plateau, using the genus Orinus (Poaceae) as a model system for an integrative approach to delimiting species.
  
  
  METHODS
  A total of 786 individuals from 102 populations of six previously recognized species were collected for niche, morphological and genetic analyses. Three plastid DNA regions (matK, rbcL and trnH-psbA) and one nuclear DNA region [internal transcribed space (ITS)] were sequenced.
  
  
  RESULTS
  Whereas six species had been previously recognized, statistical analyses based on character variation, molecular data and niche differentiation identified only two well-delimited clusters, together with a third possibly originating from relatively recent hybridization between, or historical introgression from, the other two.
  
  
  CONCLUSIONS
  Based on a principle of integrative species delimitation to reconcile different sources of data, the results provide compelling evidence that the six previously recognized species of the genus Orinus that were examined should be reduced to two, with new circumscriptions, and a third, identified in this study, should be described as a new species. This empirical study highlights the value of applying genetic differentiation, morphometric statistics and ecological niche modelling in an integrative approach to re-circumscribing species boundaries. The results produce relatively objective, operational and unbiased taxonomic classifications of plants occurring in remote regions.
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, PR China and Key Laboratory of Education Ministry of Environments and Resources in the Qinghai-Tibet Plateau, School of Geography and Life Science, Qinghai Normal University, Xining 810008, PR China State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, PR China and Key Laboratory of Education Ministry of Environments and Resources in the Qinghai-Tibet Plateau, School of Geography and Life Science, Qinghai Normal University, Xining 810008, PR China.
authors.forename: Xu
authors.initials: X
authors.lastname: Su
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, PR China and Key Laboratory of Education Ministry of Environments and Resources in the Qinghai-Tibet Plateau, School of Geography and Life Science, Qinghai Normal University, Xining 810008, PR China.
authors.forename: Guili
authors.initials: G
authors.lastname: Wu
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, PR China and Key Laboratory of Education Ministry of Environments and Resources in the Qinghai-Tibet Plateau, School of Geography and Life Science, Qinghai Normal University, Xining 810008, PR China.
authors.forename: Lili
authors.initials: L
authors.lastname: Li
authors.affiliation: State Key Laboratory of Grassland Agro-Ecosystem, School of Life Science, Lanzhou University, Lanzhou 730000, PR China and Key Laboratory of Education Ministry of Environments and Resources in the Qinghai-Tibet Plateau, School of Geography and Life Science, Qinghai Normal University, Xining 810008, PR China liujq@lzu.edu.cn.
authors.forename: Jianquan
authors.initials: J
authors.lastname: Liu
mesh_terms: D001483:Base Sequence; D016000:Cluster Analysis; D018742:DNA, Chloroplast / Q000235:genetics; D021901:DNA, Intergenic / Q000235:genetics; D017753:Ecosystem; D005843:Geography; D008969:Molecular Sequence Data; D009711:Nucleotides / Q000235:genetics; D010802:Phylogeny; D006109:Poaceae / Q000502:physiology*; D025341:Principal Component Analysis; D019655:Quantitative Trait, Heritable; D027343:Rhizome / Q000502:physiology; D013045:Species Specificity; D018609:Tibet
chemical_list: D018742:DNA, Chloroplast; D021901:DNA, Intergenic; D009711:Nucleotides
keywords: Orinus; PCoA; Poaceae; Qinghai–Tibet Plateau; genetic gaps; niche differentiation; principal co-ordinate analysis; species delimitation