Two genetic divergence centers revealed by chloroplastic DNA variation in populations of Cinnamomum kanehirae Hay.

Cinnamomum kanehirae Hayata (Lauraceae), the most valuable subtropical and temperate broadleaf timber tree in Taiwan, is rapidly disappearing from the wild. Taking advantage of a scion garden established by the Taiwan Forestry Research Institute, we examined patterns of chloroplast DNA (cpDNA) variations in 19 populations including 94 individuals. By sequencing two cpDNA fragments using universal primers (the trnL- trnF and petG- trnP intergenic spacers), we found eight polymorphic sites, six haplotypes, and extremely low nucleotide diversity ( π = 0.00016) from 792 bp aligned sequences. The ancestral haplotype is widely distributed. Among the populations studied, three separated populations, at Yungfeng, Fuli, and Tahu have high nucleotide diversity. No phylogeographical structures of haplotypes were revealed because the tests of N_ST− G_ST for populations did not differ from zero in any situations; a ‘star-like’ genealogy is characteristic when all haplotypes rapidly coalesce and is a general outcome of population expansion. The neutrality test also suggested demographic expansion. The genetic divergence and diversity analyses suggested that two potential refugia existed during the last glaciation with a major one located in southeastern Taiwan and a minor one located in Tahu in north-central Taiwan in the Hsuehshan Range, west of the Central Mountain Range. [ABSTRACT FROM AUTHOR]