Effects of floral restrictiveness and stigma size on heterospecific pollen receipt in a prairie community
Effects of floral restrictiveness and stigma size on heterospecific pollen receipt in a prairie community
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DOI：
10.1007/s00442-011-2094-x
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发表时间：
2012-02-01
期刊：
影响因子：
2.7
通讯作者：
Rathcke, Beverly J.
中科院分区：
文献类型：
--
作者：
Montgomery, Benjamin R.;Rathcke, Beverly J.
植物种类在花形态限制进入花内部的程度上有很大差异。花冠的限制性可能会影响异种花粉的接受，但花形态对异种花粉转移的影响却鲜有人关注。我们描述了草原群落中29种不同花型的传粉者访问和接受同种和异种花粉的数量，草原群落以引入的植物一品红为主导，具有非限制性的形态。大戟花与其他非限制性花之间的传粉器重叠显著大于限制性花。与具有限制性形态的花相比，非限制性花收到的大戟花花粉明显更多，来自其他来源的异种花粉更多，花粉种类更多样，但不是更多的同种花粉。然而，形态不受限制的花的柱头表面积显著较大，大戟属和其他异种花粉的每柱头面积密度在不同花类型之间没有显著差异。这些发现表明，限制性花的柱头尺寸较小是其异种花粉接收减少的部分原因，但这种限制性也允许物种增加它们接收的花粉的纯度。考虑到限制性花收到的异种花粉粒较少，但密度较高，限制对繁殖力的影响取决于异种花粉的绝对量和密度中哪一个对育性的影响更大。我们的结果还表明，丰富的邻居不一定是重要的异种花粉来源，因为大戟属的花粉在异种上很少丰富。
Plant species vary greatly in the degree to which floral morphology restricts access to the flower interior. Restrictiveness of flower corollas may influence heterospecific pollen receipt, but the impact of floral morphology on heterospecific pollen transfer has received little attention. We characterized patterns of pollinator visitation and quantities of conspecific and heterospecific pollen receipt for 29 species with a range of floral morphologies in a prairie community dominated by the introduced plant Euphorbia esula (leafy spurge) which has an unrestrictive morphology. Pollinator overlap was significantly greater between Euphorbia and other unrestrictive flowers than restrictive flowers. Compared to flowers with restrictive morphologies, unrestrictive flowers received significantly more Euphorbia pollen, more heterospecific pollen from other sources, and a greater diversity of pollen species, but not more conspecific pollen. However, stigmatic surface area was significantly larger for flowers with unrestrictive morphologies, and the density of Euphorbia and other heterospecific pollen per stigmatic area did not significantly differ between flower types. These findings suggest that the smaller stigma size in restrictive flowers partly accounts for their decreased heterospecific pollen receipt, but that restrictiveness also allows species to increase the purity of pollen loads they receive. Given that restrictive flowers receive fewer heterospecific pollen grains but at a higher density, the effect of restrictiveness on fecundity depends on whether absolute quantity or density of heterospecific pollen affects fecundity more. Our results also indicate that abundant neighbors are not necessarily important heterospecific pollen sources since Euphorbia pollen was rarely abundant on heterospecifics.