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Allozyme variation in four geographic areas of Cinnamomum kanehirae

Author:
Lin, T.P., Cheng, Y.P., Huang, S.G.
Source:
Journal of heredity 1997 v.88 no.5 pp. 433-438
ISSN:
0022-1503
Subject:
Cinnamomum, alleles, allozymes, broadleaved trees, climatic factors, clones, endangered species, forestry, gene flow, genetic variation, heterozygosity, inbreeding, insect pollination, loci, research institutions, seed dispersal, seed size, statistics, woody plants, Taiwan
Abstract:
The once dominant endemic broadleaf tree species in Taiwan, Cinnamomum kanehirae Hay., has become a rare and endangered species due to overcutting. A clone bank, consisting of at least 220 clones collected islandwide, was established at the Liukuei station, Taiwan Forestry Research Institute. Genetic diversity within and genetic differentiation among four geographic areas of C. kanehirae were investigated using 164 clones collected from the clone bank. Seven out of the 11 loci examined were polymorphic. The average proportion of polymorphic loci per area was 51% at the 99% criterion for polymorphism. Mean expected heterozygosity ranged from 0.188-0.261 the different areas, and 0.238 at the species level. On average the percent heterozygous loci per individual ranged from 13.9-21.6%, the number of alleles per locus ranged from 1.7-1.9, and the effective number of alleles per locus ranged from 1.34-1.54 the area level. The much higher expected heterozygosity and higher number of alleles per locus compared to other local woody species investigated may support the hypothesis that Taiwan was a distributional center of Cinnamomum. Partitioning the genetic variability into within- and among-geographic area components with F statistics and gene diversity analysis led to an estimate of within-area variation amounting 88% of the total variation. A slight barrier to gene flow among areas could be due the large seed size and to insect pollination. The limitation of seed dispersion, erratic flowering times, and several subpopulations within the same geographic areas may contribute to the lower levels of observed heterozygosity than expected heterozygosity among the seven polymorphic loci, indicating some degree of inbreeding and the Wahlund effect and thus a slight deficiency of heterozygotes (F18 = 0.157). Area 4, located in southeastern Taiwan has a much lower elevational distribution and showed a higher proportion of polymorphic loci, implying that genetic variation of area 4 may have developed under different climate conditions.
Agid:
2040624