Chin J Plant Ecol ›› 2005, Vol. 29 ›› Issue (5): 785-792.DOI: 10.17521/cjpe.2005.0104

• Research Articles • Previous Articles     Next Articles

A COMPARATIVE STUDY ON THE GENETIC DIVERSITY OF DIPTERONIA SINENSIS AND DIPTERONIA DYERIANA

LI Shan1,2, QIAN Zeng-Qiang1, CAI Yu-Liang1, ZHAO Gui-Fang1,*()   

  1. 1 Biodiversity Research Center of Qinling Mts, College of Life Science, Northwest University, Xi'an 710069, China
    2 Institute of Bioresource and Applied Technology, School of Life Sciences and Technology, Tongji University, Shanghai 200092, China
  • Received:2004-02-18 Accepted:2005-02-03 Online:2005-02-18 Published:2005-08-30
  • Contact: ZHAO Gui-Fang
  • About author:* E-mail: guifang@nwu.edu.cn

Abstract:

Dipteronia is an endemic genus to China and includes only two species, Dipteronia sinensis and D. dyeriana. Based on RAPD markers, a comparative study on the genetic diversity and genetic structure of Dipteronia was performed. In total, 128 and 103 loci were detected in 17 D. sinensis populations and 4 D. dyeriana populations, respectively, using 18 random primers. These results showed that the proportion of polymorphic loci for the two species were 92.97% and 81.55%, respectively, indicating that the genetic diversity of D. sinensis was higher than that of D. dyeriana. Analyses based on similarity coefficients, Shannon diversity index and Nei gene diversity index, also confirmed this result. AMOVA analysis demonstrated that the genetic variation of D. sinensis within and among populations accounted for 56.89% and 43.11% of the total variation, respectively, and 57.86% and 42.14%, respectively, of D. dyeriana. The Shannon diversity index and Nei gene diversity index showed similar results. The above-mentioned characteristics indicated that the genetic diversity levels of these two species were extremely similar and that the interpopulational genetic differentiation within both species was relatively high. Analysis of the genetic distance among populations also supported this conclusion. Low levels of interpopulational gene flow within both species were believed to be among the leading causes for the above-mentioned phenomenon. The correlation analysis between genetic and geographical distances showed that there existed a remarkably significant correlation between the genetic distance and the longitude difference among populations of D. sinensis (p<0.01) while no significant correlation existed between genetic and geographical distances among populations ofD. dyeriana. This indicates that genetic distance was correlated with geographical distances at large scales other than at small scales. This result may be related to differences in selection pressure exerted on species by their habitats with different distribution ranges. We suggest that in situ conservation efforts should focus on establishing more sites to protect the natural populations and their habitats. Ex situ conservation efforts should focus on enhancing the exchange of seeds and seedlings among populations to facilitate gene exchange and recombination to help conserve genetic diversity.

Key words: Dipteronia sinensis, Dipteronia dyeriana, RAPD, Genetic diversity, Comparative study