Salas-Arcos Lucía, Lara Carlos, Ornelas Juan Francisco
Doctorado en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxala, Mexico.
Centro de Investigaciones en Ciencias Biológicas, Universidad Autónoma de Tlaxcala, Tlaxcala, Mexico.
PeerJ. 2017 Aug 9;5:e3636. doi: 10.7717/peerj.3636. eCollection 2017.
In many plant species, pollination syndromes predict the most effective pollinator. However, other floral visitors may also offer effective pollination services and promote mixed pollination systems. Several species of the species-rich (Plantaginaceae) exhibit a suite of floral traits that suggest adaptation for pollination by both hymenopterans and hummingbirds. Transitions from the ancestral hymenopteran pollination syndrome to more derived hummingbird pollination syndrome may be promoted if the quantity or quality of visits by hummingbirds is increased and if the ancestral pollinator group performs less efficiently. The quantification of such shifts in pollination systems in the group is still limited. We aimed to investigate floral traits linked to this pollination syndrome in with flowers visited by bumblebees and hummingbirds.
We investigated the floral biology, pollinator assemblages, breeding system and nectar production patterns of inhabiting a temperate montane forest in central Mexico. Pollination experiments were also conducted to assess the pollinator effectiveness of bumblebees and hummingbirds.
flowers are protandrous, with 8-d male phase (staminate) flowers, followed by the ∼1-7 d female phase (pistillate phase). Flowers display traits associated with hymenopteran pollination, including purple flowers abruptly ampliate-ventricose to a broad throat with anthers and stigmas included, and long lifespans. However, the nectar available in the morning hours was abundant and dilute, traits linked to flowers with a hummingbird pollination syndrome. Two hummingbird species made most of the visits to flowers, (30.3% of all visits), followed by (11.3%). Bumblebees (, and ) accounted for 51.8% of all recorded visits, but their foraging activity was restricted to the warmer hours. Hummingbirds made more foraging bouts and visited more flowers than hymenopteran species. Flowers experimentally pollinated by produced significantly more fruits than those pollinated by . However, there was no statistical difference in the number of seeds produced per fruit when a bumblebee or a hummingbird was the pollinator.
We have shown that bumblebees and hummingbirds visit and pollinate flowers. Despite floral traits resembling the hymenoptera pollination syndrome, flowers of offer characteristic nectar rewards to flowers with a hummingbird pollination syndrome. Although pollination efficiency is higher among flowers visited by hymenoptera, the noteworthy percentage of fruit production and number of seeds per fruit derived from hummingbird pollination highlights the importance of hummingbirds as a functional group of pollinators that might have potential evolutionary consequences to the plants.
在许多植物物种中，授粉综合征可预测最有效的传粉者。然而，其他访花者也可能提供有效的授粉服务并促进混合授粉系统。物种丰富的车前科的几个物种表现出一系列花部特征，表明它们适应了膜翅目昆虫和蜂鸟的授粉。如果蜂鸟的访花数量或质量增加，且原始传粉者群体的授粉效率降低，那么从原始的膜翅目授粉综合征向更衍生的蜂鸟授粉综合征的转变可能会得到促进。该类群授粉系统中此类转变的量化研究仍然有限。我们旨在研究与这种授粉综合征相关的花部特征，该综合征存在于被大黄蜂和蜂鸟访花的[植物名称]中。
我们调查了栖息于墨西哥中部温带山地森林中的[植物名称]的花生物学、传粉者组合、繁育系统和花蜜分泌模式。还进行了授粉实验，以评估大黄蜂和蜂鸟的传粉有效性。
[植物名称]的花是雄性先熟的，有8天的雄花阶段（雄蕊期），随后是约1 - 7天的雌花阶段（雌蕊期）。花表现出与膜翅目授粉相关的特征，包括紫色的花突然膨大呈腹状至宽阔的喉部，花药和柱头内藏，以及寿命长。然而，早晨时段可获得的花蜜丰富且稀薄，这些特征与具有蜂鸟授粉综合征的花相关。两种蜂鸟对[植物名称]花的访花次数最多，[蜂鸟物种1]（占所有访花次数的30.3%），其次是[蜂鸟物种2]（11.3%）。大黄蜂（[大黄蜂物种1]、[大黄蜂物种2]和[大黄蜂物种3]）占所有记录访花次数的51.8%，但它们的觅食活动仅限于较温暖的时段。蜂鸟比膜翅目物种进行更多的觅食回合且访花更多。经[蜂鸟物种]实验授粉的花产生的果实明显多于经[大黄蜂物种]授粉的花。然而，当大黄蜂或蜂鸟作为传粉者时，每个果实产生的种子数量没有统计学差异。
我们已经表明大黄蜂和蜂鸟会访花并为[植物名称]花授粉。尽管花部特征类似于膜翅目授粉综合征，但[植物名称]的花为具有蜂鸟授粉综合征的花提供了典型的花蜜回报。尽管膜翅目访花的花授粉效率更高，但蜂鸟授粉产生的果实百分比和每个果实的种子数量值得注意，这突出了蜂鸟作为传粉者功能群的重要性，这可能对植物产生潜在的进化影响。
