CHEN, CHARLES*, KERMIT RITLAND, AND SHONG HUANG. 1,2. Department of Forest Sciences, 2424 Main Mall, University of British Columbia, Vancouver, British Columbia, Canada, V6T 1Z4, 3. Department of Biology, 88 Ting-Chou Road, Taipei, Taiwan ROC. - Genetic variation and differentiation in Hypericum nagasawai, an endemic plant in Taiwan.
Hypericum nagasawai is an endemic perennial herb that grows on
rocky slope, streambanks and roadside in the high mountain areas of
Taiwan. In total 256 clones randomly selected from 8 populations were
electrophoretically analyzed for 16 isozyme loci. Although it is
endemic to the island, compared with other similarly geographic range
flowering plants, 0.169 of average expected heterozygosity and 64.3%
polymorphic loci, H. nagasawai possesses higher amount of
genetic variation. Levels of Wright's gene fixation F were not
significantly different from 0 (FIS=0.005;
FIT=0.067), indicating possible geneflow and a random
mating strategy. Since the small magnitude of FST , the
homogenous distribution of genetic variation represented little
genetic differentiation among the studied populations. Cluster
analysis based on Nei's unbiased genetic distance illustrated genetic
structure within this species. It is congruent with the morphological
survey, showing two major groups segregating in a north-south
distribution, with little genetic isolation. In regards to the
ambiguous systematic relationship between highly related H.
nagawasai and H. nokoense, possibly frequent genetic
exchange and sympatric habitat could be the possible reasons why they
are systematically different taxa but yet not having recognizable
differences.
Key words: genetic differentiation,genetic diversity,Hypericaceae,Hypericum nagasawai,Isozyme