生物多样性 ›› 2017, Vol. 25 ›› Issue (6): 615-620.doi: 10.17520/biods.2017029

• 研究报告 • 上一篇    下一篇

牛耳朵和马坝报春苣苔同域种群授粉后的生殖隔离

张小龙1, 杨丽华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:2017-02-01 接受日期:2017-04-06 出版日期:2017-06-20
  • 通讯作者: 康明 E-mail:mingkang@scib.ac.cn
  • 基金项目:
    国家自然科学基金-广东省联合基金重点项目(U1501211)

Post-pollination reproductive isolation of sympatric populations of Primulina eburnea and P. mabaensis (Gesneriaceae)

Xiaolong Zhang1, Lihua Yang1, 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 Chinese Academy of Sciences, Beijing 100049
  • Received:2017-02-01 Accepted:2017-04-06 Online:2017-06-20
  • Contact: Kang Ming E-mail:mingkang@scib.ac.cn

生殖隔离是物种形成的关键, 也是物种保持完整性和独立性的基础。报春苣苔属(Primulina)是我国苦苣苔科中最大的属, 具有极为丰富的物种多样性。大部分报春苣苔属植物为喀斯特地区特有植物, 近缘种的同域分布也相当普遍。为更好地理解该属植物的物种多样性形成及维持机制, 我们选取了牛耳朵(P. eburnea)和马坝报春苣苔(P. mabaensis)的同域种群, 分析了授粉后的多种隔离机制强度, 主要包括花粉竞争、坐果率、种子重量、种子萌发率、花粉活力。结果显示, 牛耳朵和马坝报春苣苔的授粉后总隔离强度都较弱(0.09 vs. 0.13), 其中花粉竞争及种子萌发率的隔离强度为负值, 对物种间基因流发生起促进作用; 而坐果率、种子重量以及花粉活力的隔离强度均为正值, 表现为对种间基因流起阻止作用。牛耳朵和马坝报春苣苔较弱的授粉后隔离机制不足以完全阻止物种间杂交、保持物种独立性, 但野外较少存在自然杂交个体暗示着两者可能存在较强的授粉前隔离机制。

关键词: 喀斯特植物, 报春苣苔属, 同域种群, 生殖隔离, 杂交, 花粉竞争

Reproductive isolation is essential for sympatric populations of closely related species to maintain species integrity and to prevent genetic introgression caused by hybridization. Primulina is the largest genus of Gesneriaceae in China, with a high degree of species diversity and endemism. Most species of the genus are karst habitat specialists (i.e. calciphiles), and many closely related species show a sympatric distribution in karst landscapes. To better understand the mechanism of sympatry in Primulina, post-pollination reproductive isolation, including pollen competition, fruit set, seed mass, seed germination, and pollen viability, was investigated in two closely related species, P. eburnea and P. mabaensis. Results indicated that the total post-pollination isolation strength for P. eburnea and P. mabaensis was 0.09 and 0.13, respectively, which were not strong enough to prevent hybridization completely. The strength of reproductive isolation from pollen competition and seed germination of P. eburnea and P. mabaensis was negative, suggesting facilitation for gene flow between species; while the strength of the fruit set, seed mass, and pollen viability showed a weak role in preventing interspecies hybridization. However, the two species are able to maintain their integrity well, as rare hybrid individuals are found in nature, suggesting that the existence of pre-pollination isolation mechanisms may play a more important role in maintaining species boundaries in these two species.

Key words: karst plant, Primulina, sympatric populations, reproductive isolation, hybridization, pollen competition

图1

牛耳朵、马坝报春苣苔及其杂交F1代植株、花和叶。(A)牛耳朵和马坝报春苣苔野外植株; (B)牛耳朵(右)、杂交F1代(中)和马坝报春苣苔(左)的叶; (C)马坝报春苣苔花药; (D)牛耳朵花药; (E)牛耳朵花; (F)杂交F1代花; (G)马坝报春苣苔花。"

表1

SSR引物信息及扩增长度多态性"

引物名称
Primer
正向引物
Forward primer
反向引物
Reverse primer
扩增片段长度多态性 Amplified fragment length polymorphism (bp)
牛耳朵 Primulina eburnea 马坝报春苣苔 P. mabaensis
325 AACGGAGAACACCCCATTTA TCGCCTTATGAAGGTTTTGG 249 246
415 AACCCATCGTTTCACTCCAC CTCGGAATCAACTCCTAGCG 289 299
1143 CGGAGTCAGCTTTGCACATA CTCTCTCCTACACACGAGCG 222 219

表2

各种生殖隔离机制强度的计算及其变量情况"

隔离机制 Isolation barriers 计算方程 Equation for calculating reproductive isolation (RI)
花粉竞争 1-2×[异源花粉授粉率/(异源花粉授粉率+同源花粉授粉率)]
Pollen competition 1-2×[interspecific pollination ratio/(interspecific pollination rate + intraspecific pollination rate)]
坐果率 1-2×[杂交坐果率/(杂交坐果率+自交坐果率)]
Fruit set 1-2×[interspecific fruit set/(interspecific fruit set + selfing fruit set)]
种子重量 1-2×[杂交种子重量/(杂交种子重量+自交种子重量)]
Seed mass 1-2×[interspecific seed mass of per fruit /(interspecific seed mass of per fruit + selfing seed mass of per fruit) ]
种子萌发率 1-2×[杂交种子萌发率/(杂交种子萌发率+自交种子萌发率)]
Seed germination rate 1-2×[interspecific seed germination/(interspecific seed germination + selfing seed germination)]
花粉活力 1-2×[杂交F1代花粉活力/(杂交F1代花粉活力+亲本花粉活力)]
Pollen viability 1-2×[interspecific F1 pollen viability/(interspecific F1 pollen viability + parent pollen viability)]

表3

牛耳朵和马坝报春苣苔授粉后各生殖隔离机制的强度"

隔离机制
Isolation barriers
牛耳朵
P. eburnea
马坝报春苣苔
P. mabaensis
花粉竞争 Pollen competition -0.321 -0.026
坐果率 Fruit set 0.058 0.003
种子重量 Seed mass 0.157 0.019
种子萌发率 Seed germination rate -0.068 -0.199
花粉活力 Pollen viability 0.264 0.333
授粉后隔离总强度 RI 0.090 0.130
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