Department of Ecology andEvolutionary Biology, University of California, Irvine, California92697-2525.
Am J Bot. 1998 Oct;85(10):1377-88.
The transition from biotic to wind pollination and the consequencesof this transition for the evolution of dioecious breeding systems wereinvestigated in Schiedea and Alsinidendron(Caryophyllaceae: Alsinoideae), genera endemic to the Hawaiian Islands. The potential for wind pollination was studied for five species ofSchiedea using a wind tunnel. Morphological correlates of windpollination for these species were then used to infer the presence orabsence of wind pollination in the remaining Schiedea species. Hermaphroditic Alsinidendron and Schiedea species,which occur in mesic to wet forests, or less commonly in dry habitats,show little or no indication of wind pollination. These species had lowpollen:ovule ratios, large relative pollen size, diffuse inflorescences,substantial nectar production in several cases, and appear to bebiotically pollinated or autogamous. Sexually dimorphic species, whichall occur in dry habitats, are wind pollinated, based on wind tunnelresults or morphological adaptations indicating the potential for windpollination. These adaptations include high pollen:ovule ratios, smallpollen size, moderately to highly condensed inflorescences, and reducednectaries and nectar production. Shifts to wind pollination anddimorphism are strongly correlated in Schiedea, suggesting theclose functional relationship of the twophenomena.
本研究以夏威夷特有科石竹科繁缕亚科的 Schiedea 和 Alsinidendron 属为材料，探讨了生物传粉向风媒传粉的转变及其对雌雄异株繁育系统进化的影响。利用风洞对 Schiedea 属的五个物种的风媒传粉潜力进行了研究。然后，利用这些物种的风媒传粉形态特征来推断其余 Schiedea 物种是否存在风媒传粉。在潮湿到湿润森林或较少见于干旱生境中的两性花的 Alsinidendron 和 Schiedea 物种，显示出很少或没有风媒传粉的迹象。这些物种的花粉：胚珠比低，花粉相对较大，花序疏松，在某些情况下花蜜产量较大，似乎是生物传粉或自交的。基于风洞结果或表明有潜力进行风媒传粉的形态适应，所有存在于干旱生境中的雌雄异株物种均为风媒传粉。这些适应包括高花粉：胚珠比、小花粉大小、中度到高度密集的花序以及减少的蜜腺和花蜜产量。Schiedea 属中向风媒传粉和雌雄异形的转变密切相关，表明这两种现象之间存在紧密的功能关系。
