Influences of animal pollination and seed dispersal on winter flowering in a temperate mistletoe
Influences of animal pollination and seed dispersal on winter flowering in a temperate mistletoe
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DOI：
10.1890/02-0521
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发表时间：
2003-10-01
期刊：
影响因子：
4.8
通讯作者：
Aizen, MA
中科院分区：
文献类型：
--
作者：
Aizen, MA
开花时间的演变可以直接受到传粉者的影响，也可以间接受到种子传播者的影响。在温带地区，与气候的相互作用，特别是温度，可能会影响植物和它们的动物互惠。冬季开花的植物允许评估生物影响开花时间的演变，因为温度不太可能直接选择这种不寻常的生殖行为。在巴塔哥尼亚的西北部，半寄生的槲寄生花Tristerix corymbosus从初秋开始开花，经过凉爽的冬天，直到晚春。该物种由蜂鸟Sephanoides galeritus授粉，其种子由有袋动物Dromiciops australis传播。在两个种群在两年中，我分析了季节性变化的授粉，水果生产和水果去除。蜂鸟的访问是最低的冬季和春末，在这些期间开放的花朵减少授粉和坐果，部分原因是传粉限制，相比，在秋季或早春开放的花朵。在夏季（1月至3月）成熟的水果有更高的机会被删除比水果成熟在春季或秋季，由于其重叠的最大扩散活动期间。开花时间与果实成熟时间和果实去除率密切相关。因此，即使在冬季开放的花朵只表现出中等的果实产量，它们的果实也受益于夏季中后期的高果实去除和种子传播。这些结果表明，这种植物的传播者的活动期，结合缺乏强有力的授粉限制，可能是在这个槲寄生开花物候的演变。然而，温度对花和果实发育的直接影响可能会阻止开花物候和最大互惠活动期间之间的微调匹配。
The evolution of flowering time can be influenced directly by pollinators and indirectly by seed dispersers. In temperate latitudes, interactions with climate, especially temperature, may affect both plants and their animal mutualists. Winter-flowering plants allow assessment of biotic influences on the evolution of flowering time because temperature is unlikely to select directly for this uncommon reproductive behavior. In northwestern Patagonia, the hemiparasitic mistletoe Tristerix corymbosus flowers from early fall, through the cool winter, to late spring. This species is pollinated by the hummingbird Sephanoides galeritus, and its seeds are dispersed by the marsupial Dromiciops australis. In two populations during two years, I analyzed seasonal variation in pollination, fruit production, and fruit removal. Hummingbird visitation was lowest in winter and late spring, and flowers opening during those periods showed reduced pollination and fruit set, partly due to pollinator limitation, compared to flowers that opened during fall or early spring. Fruits that ripened during summer (January-March) had a higher chance of being removed than fruits ripening during either spring or fall, due to their overlap with the period of maximum disperser activity. Timing of flower opening was strongly associated with fruit maturation time and with fruit removal rates. Thus, even though flowers that opened during winter exhibited only moderate fruit production, their fruits benefited from high fruit removal and seed dispersal in mid to late summer. These results suggest that the activity period of this plant's disperser, in combination with a lack of strong pollination constraints, probably governed the evolution of flowering phenology in this mistletoe. However, the proximate influence of temperature on flower and fruit development may prevent a fine-tuned match between flowering phenology and the period of maximum mutualist activity.