Biodiv Sci ›› 2004, Vol. 12 ›› Issue (6): 564-571.DOI: 10.17520/biods.2004071

• 论文 •     Next Articles

Genetic structure of Xiuning population of Isoetes sinensis, a critically endangered species in China

CHEN Yuan-Yuan, YE Qi-Gang, LI Zuo-Zhou, HUANG Hong-Wen*   

  1. Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074
  • Received:2004-04-02 Revised:2004-09-05 Online:2004-11-20 Published:2004-11-20
  • Contact: HUANG Hong-Wen

Abstract: Allozymic variation and genetic structure of five subpopulations of Isoetes sinensis sampled from Xiuning, Anhui Province were investigated using isoelectric focusing in thin-layer polyacrylamid slab gels. Eighteen loci of 10 enzyme systems were examined and used for the analysis of population genetic parameters. A high genetic diversity was observed in the population, with mean number of alleles per loci (A)=1.7, mean percentage of polymorphic loci(P)=55.56 %, and average expected heterozygosity (He) =0.201. These parameters of genetic diversity were much higher than the average values in fern species. Excess fixed heterozygotes “aabb” found in the population were greatly responsible for deviation from Hardy-Weinberg equilibrium at some polymorphic loci. No significant difference in genetic variation was found among the five subpopulations. Partitioning the genetic diversity indicated that 94.27% of the genetic variation was within subpopulations and only 5.73% existed between subpopulations, which was explained by a genetic bottleneck or founder effect, as well as by the clonal reproduction of this species and “fixed heterozygosity”. Mean gene flow among subpopulations (Nm) was 4.5062 and genetic identities among subpopulations ranged from 0.960 to 0.999, which is suggestive evidence that the Xiuning population is panmictic in its current habitat. Furthermore, the sampled population with a total of 75 individuals consists of only 13 multi-locus genotypes, suggesting a high genetic uniformity within and among subpopulations. Finally, we discuss the risk of extinction of this species in the wild driven by population genetic factors, and conservation strategies.

Key words: planted vegetation, χ2 test, Spearman rank correlation, grey incidence recognition

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