毛姜花原变种花寿命对两性适合度的影响

  植物的花寿命被认为是由雌、雄适合度的增长和维持花开放的花费之间的平衡来决定的。姜花属(Hedychium)是姜科唯一一个从热带到高海拔地区分布的大属, 属内不同种类植物的花寿命差异很大。毛姜花原变种(H. villosum var. villosum)的花寿命为5 d, 显著长于其它同域分布的姜科植物。通过人工剪除毛姜花原变种的柱头来使花朵具雌性功能的时间缩短, 结果显示: 在不同的处理中, 结实率随花朵具雌性功能时间的延长而增加, 开花1 d后剪除柱头的结实率为1.85% ± 1.59%, 极显著低于对照的结实率20.96% ± 4.13%, 说明其较长的花寿命能显著地增加传粉的成功率和结实率, 长达5 d的花寿命有利于雌性适合度的提高。同时, 毛姜花原变种开花1 d后, 剩余的平均花粉数和总平均花粉数没有显著差异, 而开花后2、3和4 d后剩余的平均花粉数则极显著少于总平均花粉数, 说明随着花寿命的延长, 花粉输出量也显著增加, 其长达5 d的花寿命也有利于其雄性适合度的提高。较长的花寿命在毛姜花原变种拓展新的生境、向更高海拔地区的扩散中也许起着重要的作用。姜科植物有着极其多样性的传粉和繁育系统, 花寿命在姜科植物传粉和繁育系统的多样性形成及其进化中起着重要作用, 同时, 较长的花寿命有效地提高了雌性适合度和雄性适合度, 从而使姜科植物能脱离热带生境, 向更高海拔的地区扩散, 花寿命在姜科植物从热带地区到高海拔地区的分布过程中也起着重要作用。

EFFECTS OF FLORAL LONGEVITY ON MALE AND FEMALE FITNESS IN HEDYCHIUM VILLOSUM VAR. VILLOSUM

Aims Floral longevity is assumed to reflect a balance between the benefit of increased pollination success and the cost of flower maintenance. Hedychium is the only large genus distributed from the tropics to high elevations in the Zingiberaceae. Members of this genus vary greatly in floral longevity. The floral longevity of H. villosum var. villosum is 5 days, which is much longer than other sympatric gingers. Our objective was to assess the effects of floral longevity on male and female fitness of H. villosum var. villosum through manipulated experiments. Methods We reduced the functional floral longevity for female function by clipping stigmas and measured the fruit-set of different treatments to test whether long flowering duration increased female fitness. We compared the pollen grain number of flowers in different stages to determine if long floral longevity benefited pollen dispersal. Important findings Fruit-set increased with increased female functional duration. Flowers with functional floral longevity of 1 day had only 1.85% ± 1.59% fruit-set, which was significantly lower than 20.96% ± 4.13% fruit-set of control flowers with natural longevity. Mean pollen grain number was similar in unopened flowers and flowers 1 day after anthesis, but less in flowers 2, 3 and 4 days after anthesis. These results indicate that long floral longevity is advantageous to both female and male fitness in H. villosum var. villosum. Long floral longevity may contribute to exploring new habitats and spreading toward high elevation areas from tropical areas in the Zingiberaceae.