title: Inferring multiple refugia and phylogeographical patterns in Pinus massoniana based on nucleotide sequence variation and DNA fingerprinting.
abstract: BACKGROUND
  Pinus massoniana, an ecologically and economically important conifer, is widespread across central and southern mainland China and Taiwan. In this study, we tested the central-marginal paradigm that predicts that the marginal populations tend to be less polymorphic than the central ones in their genetic composition, and examined a founders' effect in the island population.
  
  
  RESULTS
  We examined the phylogeography and population structuring of the P. massoniana based on nucleotide sequences of cpDNA atpB-rbcL intergenic spacer, intron regions of the AdhC2 locus, and microsatellite fingerprints. SAMOVA analysis of nucleotide sequences indicated that most genetic variants resided among geographical regions. High levels of genetic diversity in the marginal populations in the south region, a pattern seemingly contradicting the central-marginal paradigm, and the fixation of private haplotypes in most populations indicate that multiple refugia may have existed over the glacial maxima. STRUCTURE analyses on microsatellites revealed that genetic structure of mainland populations was mediated with recent genetic exchanges mostly via pollen flow, and that the genetic composition in east region was intermixed between south and west regions, a pattern likely shaped by gene introgression and maintenance of ancestral polymorphisms. As expected, the small island population in Taiwan was genetically differentiated from mainland populations.
  
  
  CONCLUSIONS
  The marginal populations in south region possessed divergent gene pools, suggesting that the past glaciations might have low impacts on these populations at low latitudes. Estimates of ancestral population sizes interestingly reflect a recent expansion in mainland from a rather smaller population, a pattern that seemingly agrees with the pollen record.
authors.affiliation: Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou, China.
authors.forename: Xue-Jun
authors.initials: XJ
authors.lastname: Ge
authors.forename: Tsai-Wen
authors.initials: TW
authors.lastname: Hsu
authors.forename: Kuo-Hsiang
authors.initials: KH
authors.lastname: Hung
authors.forename: Chung-Jian
authors.initials: CJ
authors.lastname: Lin
authors.forename: Chi-Chung
authors.initials: CC
authors.lastname: Huang
authors.forename: Chao-Ching
authors.initials: CC
authors.lastname: Huang
authors.forename: Yu-Chung
authors.initials: YC
authors.lastname: Chiang
authors.forename: Tzen-Yuh
authors.initials: TY
authors.lastname: Chiang
mesh_terms: D001483:Base Sequence; D016172:DNA Fingerprinting; D018744:DNA, Plant / Q000235:genetics*; D014644:Genetic Variation; D006239:Haplotypes / Q000235:genetics; D018895:Microsatellite Repeats / Q000235:genetics; D009711:Nucleotides / Q000235:genetics*; D009792:Oceans and Seas; D058974:Phylogeography; D028223:Pinus / Q000145:classification / Q000235:genetics*; D011156:Population Density
chemical_list: D018744:DNA, Plant; D009711:Nucleotides