Phylogeographic study reveals the origin and evolutionary history of a Rhododendron species complex in Taiwan.
This study infers a single origin and a once-widespread distribution of the Rhododendron pseudochrysanthum species complex in Taiwan based on chloroplast DNA (cpDNA) variation. In total, 124 individuals from five endemic Rhododendron species were used for amplifications of two chloroplast intergenic spacers: trnL-trnF and atpB-rbcL. The haplotype and nucleotide diversities were much lower for the R. pseudochrysanthum complex, comprised of the species R. pseudochrysanthum, R. morii, Rhododendron rubropunctatum, and Rhododendron hyperythrum, than for Rhododendron formosanum. Two measures of pairwise population differentiation, N(ST) and F(ST), consistently revealed mostly non-significant levels of genetic divergence between populations of the R. pseudochrysanthum complex. No genetic difference was found among the four species of the R. pseudochrysanthum complex by analysis of molecular variance (AMOVA), which is concordant with the parsimonious topology of cpDNA haplotypes for the complex. Nested clade analysis (NCA) of the cpDNA haplotypes indicated that restricted gene flow with isolation-by-distance characterized the recolonization pattern of the R. pseudochrysanthum complex. In contrast, the NCA analysis indicated a contiguous range expansion for cpDNA haplotypes of R. formosanum. This research suggests a once-widespread distribution of the R. pseudochrysanthum complex probably via north-to-south colonization of mid-elevations during low-temperature periods of the Pleistocene. Population fragmentation followed the warmer climate which began in the Holocene and resulted in the present-day range contraction into high elevations.
Chung
Jeng-Der
JD
Division of Silviculture, Taiwan Forestry Research Institute, 53 Nanhai Road, Taipei 10066, Taiwan.
Lin
Tsan-Piao
TP
Chen
Yu-Ling
YL
Cheng
Yu-Pin
YP
Hwang
Shih-Ying
SY
D018742:DNA, Chloroplast / Q000737:chemistry / Q000235:genetics*; D019143:Evolution, Molecular; D014644:Genetic Variation; D005843:Geography; D006239:Haplotypes / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D029793:Rhododendron / Q000145:classification / Q000235:genetics*; D017422:Sequence Analysis, DNA; D013624:Taiwan
D018742:DNA, Chloroplast