Preliminary Study Of Molecular Phylogenetics And Biogeography Of The Genus Camellia L. Based On Chloroplast DNA

Camellia L.is the largest and relatively primitive genus in family Theaceae.There are three taxonomic treatments of the genus Camellia frequently refereed to Camellia literatures: Sealy's treatment,Chang's treatment and Ming's treatment.But these treatments are still controversial in classifications of subgenera,sections or species delimitation.Therefore,it is significant to further study the taxonomic problem of genus Camellia.1)Phylogeny and classification of the genus CamelliaThrough sampling of Camellia in wild and herbarium,we obtained 161 taxa of the genus.These taxa covered all four subgenus and sixteen sections.Representatives from Gordonia and Tutcheria were used as outgroup.We isolated four molecular fragments from plastid DNA(mat K,trn L-F,rbc L and ycf1).And we reconstructed the molecular phylogenetic trees of Camellia use maximum parsimony,maximum likelihood and Bayesian inference methods.The phylogeny showed thirteen major lineages(A-M)was recognized within Camellia: clade A and B mainly consist of species of sect.Camellia;clade C and I mainly consist of sect.Theopsis,and sect.Eriandria is also distributed in these two clade;clade D and J mainly consisted of sect.Thea;clade F consist of sect.Paracamellia;clade G and M consist of sect.Furfuracea;clade H consists of sect.Tuberculata and three species of sect.Pseudocamellia;clade K and L mainly consist of sect.Chrysantha.The phylogenetic clades showed that the previous morphology based classification of Camellia is not supported.We proposed the need of a revision of Camellia by combing molecular phylogenetic results,morphological characters and geographic distribution pattern.2)Character evolution in CamelliaWe inferred the evolutionary trends of four morphological characteristics of Camellia by reconstructing the ancestral character state using the unordered parsimony model in MESQUITE.The result showed the ancestor of the genusCamellia were long anthocaulus,bract differentiation,androecium united at the base,gynoecium slightly divided at the tip.The results support that the genus Camellia evolves in the direction of anthocaulus being shorter,bract differentiation results is in according with the Ming's hypothesis “bract differentiation is the result of anthocaulus being shorter”.3)Panbiogeographical analysis of CamelliaIn this paper,a panbiogeograpgical analysis was conducted in order to assess the distribution pattern and evolution of Camellia.Distribution data of 1731 records of161 species were obtained from herbaria and monograph.Track analysis of panbiogeography using software MARTITRACK to analyze the dataset.The results generated 13 MSTs and 10 generalized tracks.All the generalized tracks contain sect.Oleifera,which indicated the existence of ancestor area of sect.Oleifera and other sections of the genus Camellia.Dispersal probably only occurred in limited and/or local regions,and the disjunction most likely results from geological historical events,Qinghai-Tibet Plateau uplift,and Asian monsoon oscillation.