生物多样性 ›› 2017, Vol. 25 ›› Issue (6): 638-646.DOI: 10.17520/biods.2017060

• 研究报告 • 上一篇    下一篇

野牡丹属两个海南特有种与同属广布种自然杂交的分子证据

周秋杰1, 蔡亚城1, 黄伟伦1, 吴伟1, 代色平2, 王峰3, 周仁超1,*()   

  1. 1 中山大学生命科学学院, 广州 510275
    2 广州市林业和园林科学研究院, 广州 510520
    3 暨南大学药学院, 广州 510632
  • 收稿日期:2017-02-27 接受日期:2017-04-12 出版日期:2017-06-20 发布日期:2017-07-10
  • 通讯作者: 周仁超
  • 基金资助:
    国家自然科学基金(31670210)、中央高校基本科研业务费(15lgjc23)和广东省科技计划项目(2015A030302011)

Molecular evidence for natural hybridization between two Melastoma species endemic to Hainan and their widespread congeners

Qiujie Zhou1, Yacheng Cai1, Wei Lun Ng1, Wei Wu1, Seping Dai2, Feng Wang3, Renchao Zhou1,*()   

  1. 1 School of Life Sciences, Sun Yat-sen University, Guangzhou 510275
    2 Guangzhou Institute of Forestry and Landscape Architecture, Guangzhou 510520
    3 College of Pharmacy, Jinan University, Guangzhou 510632
  • Received:2017-02-27 Accepted:2017-04-12 Online:2017-06-20 Published:2017-07-10
  • Contact: Zhou Renchao

摘要:

自然杂交既可以在物种形成、遗传交换和适应性进化方面发挥重要作用, 也可以造成稀有种的下降甚至灭绝以及超级入侵种的产生。涉及到稀有种的自然杂交研究可以为稀有种的保护提供重要的信息。紫毛野牡丹(Melastoma penicillatum)和枝毛野牡丹(M. dendrisetosum)是野牡丹属的两个海南特有种, 其中枝毛野牡丹已处于濒危状态。我们的野外调查和形态观察发现, 海南吊罗山存在紫毛野牡丹和野牡丹(M. candidum)以及枝毛野牡丹和毛菍(M. sanguineum)的嫌疑杂种个体。本研究测定并分析了这些嫌疑杂种及其嫌疑亲本的4个核基因和5个叶绿体基因间隔区序列, 发现嫌疑杂种个体在嫌疑亲本物种的固定替换位点上均为嫌疑亲本物种碱基的杂合状态, 单倍型网络分析表明所有嫌疑杂种个体在每个核基因上均具有来自两个嫌疑亲本的等位基因, 证实了紫毛野牡丹和野牡丹, 以及枝毛野牡丹和毛菍之间确实存在自然杂交。另外, 相对于其他野牡丹属物种, 枝毛野牡丹具有极低的遗传多样性。因为紫毛野牡丹和野牡丹、枝毛野牡丹和毛菍之间均存在很强的生态隔离, 所以因公路修建而造成的生境干扰可能造成了这两个杂交事件的发生。因此避免生境干扰是保护这两个海南特有种最关键的手段。除此之外, 在实验室条件下进行种子萌发或枝条扦插繁殖, 然后将幼苗种植到合适生境中是扩大种群的另一个可行方法。

关键词: 野牡丹属, 自然杂交, 濒危物种, 核基因, 叶绿体基因间隔区, 保护

Abstract:

Natural hybridization plays an important role in speciation, genetic exchange, and adaptive evolution. However, it can also lead to the extinction of rare species or can generate super invasive species. Studies of natural hybridization involving rare species can therefore provide valuable information for species protection. In Melastoma, M. penicillatum and M. dendrisetosum are endemic to Hainan, China. M. dendrisetosum is at the edge of extinction, with a wild population of less than 300 individuals. Based on morphological observations during our field survey, we found that there are putative hybrids formed between the two endemic species and their widespread congeners, i.e. M. candidum × M. penicillatum and M. sanguineum × M. dendrisetosum. In this study, we sequenced four low-copy nuclear genes and five chloroplast DNA intergenic spacers of the putative hybrids and their putative parents. We found that these putative hybrids showed chromatogram signal additivity between putative parental species on differentially fixed sites at these nuclear genes. Haplotype networks also showed that at all four nuclear loci analyzed, alleles of the putative hybrids were shared with those of their putative parental species. The results above confirmed that hybridization occurred between M. candidum and M. penicillatum, and between M. sanguineum and M. dendrisetosum. Also, we found an extremely low level of genetic diversity in M. dendrisetosum relative to the three other species of Melastoma. It appears that there are strong ecological isolation between M. candidum and M. penicillatum as well as between M. sanguineum and M. dendrisetosum, and habitat disturbance caused by highway construction may have promoted hybridization between these species. Therefore, the key to protecting these two species endemic to Hainan is to reduce habitat disturbance. Artificial propagation of the species is another possible way to expand their population sizes.

Key words: Melastoma, natural hybridization, endangered species, nuclear genes, chloroplast intergenic spacer, conservation