Genetic population structure of the alpine species Rhododendron pseudochrysanthum sensu lato (Ericaceae) inferred from chloroplast and nuclear DNA
- Equal contributors
1 Department of Life Sciences, National Cheng-Kung University, Tainan 701, Taiwan
2 Graduate Institute of Bioresources, National Pingtung University of Science and Technology, Pingtung 912, Taiwan
3 Department of Engineering Science, National Cheng-Kung University, Tainan 701, Taiwan
4 Taiwan Endemic Species Research Institute, Nantou 552, Taiwan
BMC Evolutionary Biology 2011, 11:108 doi:10.1186/1471-2148-11-108Published: 19 April 2011
A complex of incipient species with different degrees of morphological or ecological differentiation provides an ideal model for studying species divergence. We examined the phylogeography and the evolutionary history of the Rhododendron pseudochrysanthum s. l.
Systematic inconsistency was detected between gene genealogies of the cpDNA and nrDNA. Rooted at R. hyperythrum and R. formosana, both trees lacked reciprocal monophyly for all members of the complex. For R. pseudochrysanthum s.l., the spatial distribution of the cpDNA had a noteworthy pattern showing high genetic differentiation (FST = 0.56-0.72) between populations in the Yushan Mountain Range and populations of the other mountain ranges.
Both incomplete lineage sorting and interspecific hybridization/introgression may have contributed to the lack of monophyly among R. hyperythrum, R. formosana and R. pseudochrysanthum s.l. Independent colonizations, plus low capabilities of seed dispersal in current environments, may have resulted in the genetic differentiation between populations of different mountain ranges. At the population level, the populations of Central, and Sheishan Mountains may have undergone postglacial demographic expansion, while populations of the Yushan Mountain Range are likely to have remained stable ever since the colonization. In contrast, the single population of the Alishan Mountain Range with a fixed cpDNA haplotype may have experienced bottleneck/founder's events.