生物多样性 ›› 2012, Vol. 20 ›› Issue (6): 676-684.DOI: 10.3724/SP.J.1003.2012.09083

• 研究报告 • 上一篇    下一篇

观光木片断化居群的遗传多样性和交配系统

王霞1,2, 王静1, 蒋敬虎1,2, 康明1,*()   

  1. 1 中国科学院华南植物园, 中国科学院植物资源保护与可持续利用重点实验室, 广州 510650
    2 中国科学院大学, 北京 100049
  • 收稿日期:2012-03-27 接受日期:2012-06-25 出版日期:2012-11-20 发布日期:2013-01-04
  • 通讯作者: 康明
  • 作者简介:* E-mail: mingkang@scbg.ac.cn
  • 基金资助:
    中国科学院知识创新工程重要方向性项目(KSCX2-YW-Z-1024);国家自然科学基金(31000148)

Genetic diversity and the mating system in a fragmented population of Tsoongiodendron odorum

Xia Wang1,2, Jing Wang1, Jinghu Jiang1,2, Ming Kang1,*()   

  1. 1 Key Laboratory of Plant Resources Conservation and Sustainable Utilization, South China Botanical Garden, Chinese Academy of Sciences, Guangzhou 510650
    2 University of the Chinese Academy of Sciences, Beijing 100049
  • Received:2012-03-27 Accepted:2012-06-25 Online:2012-11-20 Published:2013-01-04
  • Contact: Ming Kang

摘要:

观光木(Tsoongiodendron odorum)是我国特有的濒危植物, 有居群较小、间断分布的特点。为探讨生境片断化对观光木居群的遗传多样性和交配系统的影响, 我们采用8对微卫星引物对采自广东南昆山的观光木片断化居群的61个成株和15个家系共780个种子进行了基因分型, 调查了5个空间隔离的斑块中观光木的两代遗传多样性以及各个层次(居群、斑块及个体)的交配系统参数。结果显示: 片断化生境中观光木成株遗传多样性水平适中(HE = 0.522), 种子遗传多样性比成株稍低(HE = 0.499), 但没有显著的差异, 近交系数在种子中也没有显著的升高, 暗示生境片断化并没有侵蚀观光木的遗传多样性; 多位点交配系统分析(MLTR)结果表明, 该片断化生境中观光木为高度异交树种(tm = 1.000), 只有较少的双亲近交(biparental inbreeding)和相关性交配(correlated mating)事件发生, 但有效花粉供体(effective pollen donor)数目较少(Nep为3.7-5.4); 5个斑块间异交率差异不明显, 但小的斑块有效花粉供体相对较多; 另外, 观光木个体之间的异交率存在明显差异, 少数个体存在自交现象。这些结果为濒危物种观光木的长期保护提供了重要的遗传学信息。

关键词: Tsoongiodendron odorum, 生境片断化, 多位点交配系统分析, 保育遗传学, 微卫星

Abstract

Habitat fragmentation is one of the most serious threats to plant diversity. In general, fragmentation negatively impacts the genetic variability of plant populations due to increased random genetic drift, inbreeding, and reductions in gene flow. To investigate the effect of habitat fragmentation on genetic diversity and the mating system of Tsoongiodendron odorum, in this study, we analyzed genetic diversity and the mating system in hierarchical levels at the population, stands, and the individual scales in a fragmented T. odorum population. We sampled and mapped 61 adult individuals from the population. Using eight microsatellite loci, we genotyped a total of 780 seeds from 15 maternal trees for the mating system analysis. The results revealed moderate levels of genetic diversity in both adults (HE = 0.522) and seeds (HE = 0.499) with no significant differences between the two ontogenic stages. In addition, we did not observe a significant increase in the seeds inbreeding coefficient. Results from the multilocus mating system analysis indicated that T. odorum was an outbreeding species with a multilocus outcrossing rate (tm) of 1.000. A small number of biparental inbreeding and correlated mating events were detected in this fragmented population. We found a small number of effective pollen donors (Nep is between 3.7 and 5.4), which seems to be a common character of insect-pollinated canopy trees. Minor differences in outcrossing rates were detected among stands, and more pollen donors were found in smaller stands. However, outcrossing rate was significantly different among individuals, and a few selfing events were detected in some seed trees. These results may provide fundamental information required to establish long term conservation strategies for this endangered tree which is endemic to China.

Key words: Tsoongiodendron odorum, habitat fragmentation, multilocus mating system analysis, conservation genetics, microsatellite