生物多样性 ›› 2016, Vol. 24 ›› Issue (1): 95-101.DOI: 10.17520/biods.2015195

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“金虎尾路线”植物的花进化与传粉转变

钱贞娜1,2, 任明迅1,2,*()   

  1. 1 (海南大学热带作物种质资源保护与开发利用教育部重点实验室, 海口 570228)
    2 (海南大学园艺园林学院, 海口 570228);
  • 收稿日期:2015-07-06 接受日期:2015-09-15 出版日期:2016-01-20 发布日期:2016-06-12
  • 通讯作者: 任明迅
  • 基金资助:
    基金项目: 国家自然科学基金(31170356)、海南大学科研启动经费(kyqd1501)

Floral evolution and pollination shifts of the “Malpighiaceae route” taxa, a classical model for biogeographical study

Zhenna Qian1,2, Mingxun Ren1,2,*()   

  1. 1 Key Laboratory of Protection and Development Utilization of Tropical Crop Germplasm Resource, Ministry of Education, Hainan University, Haikou 570228
    2 College of Horticulture and Landscape Architecture, Hainan University, Haikou 570228
  • Received:2015-07-06 Accepted:2015-09-15 Online:2016-01-20 Published:2016-06-12
  • Contact: Ren Mingxun

摘要:

以金虎尾科植物地理分布格局及迁移历史总结出来的“金虎尾路线”, 是解释热带植物洲际间断分布与长距离扩散格局的重要模式。金虎尾路线阐明了金虎尾科植物历史时期7次独立的从起源中心(南美洲)向旧世界(非洲和亚洲)的洲际长距离扩散事件。本文总结了金虎尾路线植物起源地与扩散地主要类群的花部特征与传粉系统, 以探讨这些类群及类似植物长距离扩散后的花进化与传粉转变等适应规律。金虎尾科的南美洲类群都有分泌油脂的萼片腺体, 花的形态结构非常保守, 是与美洲当地特有的条蜂科集油蜂长期协同进化的结果。金虎尾科的非洲类群花保守性消失, 花白色、辐射对称且无萼片腺体, 繁育系统为雄花-两性花异株(功能性的雌雄异株), 传粉者是采集花粉的蜜蜂科昆虫。亚洲的一些属发生了类似非洲类群的泛化适应转变, 但风筝果属(Hiptage)出现了镜像花、异型雄蕊和极度反折的花瓣, 且传粉者是亚洲特有的大蜜蜂(Apis dorsata), 显示出了非常特化的适应性转变。风筝果属所在支系的现存类群涵盖了南美洲、中美洲、非洲和亚洲等地的地方特有属, 体现了金虎尾路线整个迁移历史过程, 是认识金虎尾路线及其进化适应规律的关键类群, 值得在今后的研究中加以重视。

关键词: 适应进化, 繁育系统, 长距离扩散, 间断分布, Malpighiaceae

Abstract:

The “Malpighiaceae route” is proposed based on the distribution pattern of the family Malpighiaceae to explain plant inter-continent disjunctions and long-distance dispersal during historical periods. The route involves seven inter-continent dispersals from New World (America) to Old World (Africa and Asia) in the Eocene (~ 65 Ma). Malpighiaceae has about 1,300 species, most of which are endemic to the New World and are characterized by “floral conservatism”. Floral conservatism in this family refers to its stereotyped yellow or pink flowers with paired oil-glands on each sepal, a result from co-evolution with specialized oil-collecting Anthophoridae bees. These bees, however, are absent from the Old World. In the African Malpighiaceae, floral conservatism disappeared as a result of adaptations to local pollen-collecting bees. Their flowers became white and radially symmetric, without sepal gland. Furthermore, the floral sex changed to be morphological androdioecy but functional dioecy. These results indicated that African Malpighiaceae had shifted from floral conservatism to generalized floral syndromes. In Asian Malpighiaceae, some studies reported in Aspidopterys and Ryssopterys generalized evolutionary adaptations in floral traits and pollination systems similar to African taxa. But a recent study found mirror-image flowers, a highly-specialized pollination system, in the Asia-endemic genus Hiptage. Mirror-image flowers in Hiptage show a sexual polymorphism in which the style deflects either to the left or the right side of the floral axis, which is a highly specialized mechanism promoting cross-pollination between left- and right-styled flowers via pollinators touching two sexual organs respectively with their left and right side of abdomens. Hiptage is also notable for its heteromorphic stamens, bilaterally-symmetric corolla, and extremely-reflected petals. Its main pollinators are the pollen-collecting honeybees such as Apis dorsata. These results indicate that the Asian Malpighiaceae could shift from floral conservatism to specialized pollination systems adapted to pollen-gathering honeybees. Hiptage is also distinctive for its position in a clade with complete migration history of Malpighiaceae route, having endemic genera respectively in South and Central America, Africa, and Asia. Further experimental studies on this genus and other Asia-endemic genera are needed to fully understand the Malpighiaceae route and its associated evolutionary adaptations, which will be helpful for studies on plant long-distance dispersal and inter-continent disjunctions.

Key words: adaptive evolution, breeding systems, long-distance dispersal, disjunction, Malpighiaceae