THE EVOLUTION OF FLORAL VARIATION WITHOUT POLLINATOR SHIFTS IN GORTERIA DIFFUSA (ASTERACEAE)
THE EVOLUTION OF FLORAL VARIATION WITHOUT POLLINATOR SHIFTS IN GORTERIA DIFFUSA (ASTERACEAE)
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DOI：
10.3732/ajb.0800222
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发表时间：
2009-04-01
影响因子：
3
通讯作者：
Johnson, Steven D.
中科院分区：
文献类型：
--
作者：
Ellis, Allan G.;Johnson, Steven D.
对被子植物花的多样性最广泛接受的解释之一是由Verne Grant和Ledyard Stebbins提出的传粉者转移模型。根据这一模型，花的特征（如形态、颜色、图案和气味）的最深刻的变化发生在植物在传粉者类别之间进行适应性转变时。我们测试了这个模型，通过调查的地理变化的花的形式和传粉者组合在南非的一年生雏菊Gorteria diffusa。该物种在头状花序上有精致的昆虫状装饰物，吸引属于Megapalpus属的蜂蝇。我们发现了前所未有的地理结构的种内变异水平，并确定了14个离散的形式，不同的形态和头状花序。这种变异并不是表型可塑性的线索，因为在一个普通的花园实验中，从种子生长出来的植物保持了形态之间的差异。相反的传粉者转移模型的预测，所有的人口，无论花的表型，主要是由一个单一品种的Megapalpus蜂飞授粉。G.因此，diffusa似乎出现了没有传粉者类型之间的进化转变。
One of the most widely accepted explanations for floral diversification in angiosperms is the pollinator-shift model developed by Verne Grant and Ledyard Stebbins. According to this model, the most profound changes in floral traits (such as morphology, color, patterning and scent) Occur when plants undergo adaptive shifts between pollinator classes. We tested this model through investigations of geographical variation in floral form and pollinator assemblages in the South African annual daisy Gorteria diffusa. This species has elaborate insect-like ornaments on the capitulum, which attract bee flies belonging to the genus Megapalpus. We found unprecedented levels of geographically structured intraspecific variation and identified 14 discrete forms that vary in the morphology and ornamentation of the capitulum. This variation is not clue to phenotypic plasticity because differences among forms were maintained in plants grown from seed in a common garden experiment. Contrary to predictions from the pollinator-shift model, all populations, regardless of floral phenotype, were pollinated primarily by a single species of Megapalpus bee fly. Much of the extensive variation in floral form in G. diffusa therefore appears to have arisen Without evolutionary shifts between pollinator types.