title: Phylogeny and biogeography of Cedrus (Pinaceae) inferred from sequences of seven paternal chloroplast and maternal mitochondrial DNA regions.
abstract: OBJECTIVE
  Cedrus (true cedars) is a very important horticultural plant group. It has a disjunct distribution in the Mediterranean region and western Himalaya. Its evolution and biogeography are of great interest to botanists. This study aims to investigate the phylogeny and biogeography of Cedrus based on sequence analyses of seven cytoplasmic DNA fragments.
  
  
  METHODS
  The methods used were PCR amplification and sequencing of seven paternal cpDNA and maternal mtDNA fragments, parsimony and maximum likelihood analyses of the DNA dataset, and molecular clock estimate of divergence times of Cedrus species.
  
  
  RESULTS
  Phylogenies of Cedrus constructed from cpDNA, mtDNA and the combined cp- and mt-DNA dataset are identical in topology. It was found that the Himalayan cedar C. deodara diverged first, and then the North African species C. atlantica separated from the common ancestor of C. libani and C. brevifolia, two species from the eastern Mediterranean area. Molecular clock estimates suggest that the divergence between C. atlantica and the eastern Mediterranean clade at 23.49 +/- 3.55 to 18.81 +/- 1.25 Myr and the split between C. libani and C. brevifolia at 7.83 +/- 2.79 to 6.56 +/- 1.20 Myr.
  
  
  CONCLUSIONS
  The results, combined with palaeogeographical and palaeoecological information, indicate that Cedrus could have an origin in the high latitude area of Eurasia, and its present distribution might result from vicariance of southerly migrated populations during climatic oscillations in the Tertiary and further fragmentation and dispersal of these populations. It is very likely that Cedrus migrated into North Africa in the very late Tertiary, while its arrival in the Himalayas would not have been before the Miocene, after which the phased or fast uplift of the Tibetan plateau happened.
authors.affiliation: State Key Laboratory of Systematic and Evolutionary Botany, Institute of Botany, The Chinese Academy of Sciences, Beijing 100093, China.
authors.forename: Cai-Yuan
authors.initials: CY
authors.lastname: Qiao
authors.forename: Jin-Hua
authors.initials: JH
authors.lastname: Ran
authors.forename: Yan
authors.initials: Y
authors.lastname: Li
authors.forename: Xiao-Quan
authors.initials: XQ
authors.lastname: Wang
mesh_terms: D028203:Cedrus / Q000235:genetics*; D002736:Chloroplasts / Q000235:genetics*; D004272:DNA, Mitochondrial / Q000235:genetics*; D018744:DNA, Plant / Q000235:genetics*; D005843:Geography; D010802:Phylogeny; D011157:Population Dynamics
chemical_list: D004272:DNA, Mitochondrial; D018744:DNA, Plant