Seasonal changes in pollinator activity influence pollen dispersal and seed production of the alpine shrub Rhododendron aureum (Ericaceae)
Seasonal changes in pollinator activity influence pollen dispersal and seed production of the alpine shrub Rhododendron aureum (Ericaceae)
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DOI：
10.1111/j.1365-294x.2006.02853.x
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发表时间：
2006-04-01
影响因子：
4.9
通讯作者：
Kudo, G
中科院分区：
文献类型：
--
作者：
Hirao, AS;Kameyama, Y;Kudo, G
在高山生态系统中，融雪时间的微尺度变化往往会导致同一植物种不同的开花物候和传粉者活动的季节性变化。利用5个微卫星对金叶杜鹃花期早晚的昆虫访花、花粉传播、交配模式和有性繁殖等进行了比较研究。在开花季节早期（6月中旬），访问花朵的昆虫很少，当时主要的传粉者是大黄蜂蜂王和苍蝇。相比之下，大黄蜂工人的频繁访问被观察到在本赛季后期（7月下旬）。两代花粉池结构的分析表明，花粉介导的基因流的质量更多样化的季节后期在平行的高授粉活动。每个果实的有效花粉供体数（N-ep）在季节后期增加（N-ep =早期2.2-2.7，晚期3.4-4.4）。异交率（t（m））和每果结实率（t（m）= 0.89和0.71，每果结实率（t（m）= 0.52和0.18））在早、晚两季均较小。此外，双亲近亲繁殖只发生在赛季后期。我们的结论是R. aureum在早季和晚季之间显示出截然不同的花粉运动和种子生产模式：在早季，种子生产可能很高，但遗传多样性较低，在晚季，可能由于较高的近交和近交衰退而减少，但具有更大的遗传多样性。因此，更多的传粉者活动并不总是意味着更多的花粉运动。
In alpine ecosystems, microscale variation in snowmelt timing often causes different flowering phenology of the same plant species and seasonal changes in pollinator activity. We compared the variations in insect visitation, pollen dispersal, mating patterns, and sexual reproduction of Rhododendron aureum early and late in the flowering season using five microsatellites. Insects visiting the flowers were rare early in the flowering season (mid-June), when major pollinators were bumblebee queens and flies. In contrast, frequent visitations by bumblebee workers were observed late in the season (late July). Two-generation analysis of pollen pool structure demonstrated that quality of pollen-mediated gene flow was more diverse late in the season in parallel with the high pollinator activity. The effective number of pollen donors per fruit (N-ep) increased late in the season (N-ep = 2.2-2.7 early, 3.4-4.4 late). However, both the outcrossing rate (t(m)) and seed-set ratio per fruit were smaller late in the season (t(m) = 0.89 and 0.71, seed-set ratio = 0.52 and 0.18, early and late in the season, respectively). In addition, biparental inbreeding occurred only late in the season. We conclude that R. aureum shows contrasting patterns of pollen movement and seed production between early and late season: in early season, seed production can be high but genetically less diverse and, during late season, be reduced, possibly due to higher inbreeding and inbreeding depression, but have greater genetic diversity. Thus, more pollinator activity does not always mean more pollen movement.