Visitation rate of pollinators and nectar robbers to the flowers and inflorescences of Tabebuia aurea (Bignoniaceae): effects of floral display size and habitat fragmentation
Visitation rate of pollinators and nectar robbers to the flowers and inflorescences of Tabebuia aurea (Bignoniaceae): effects of floral display size and habitat fragmentation
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DOI：
10.1111/boj.12435
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发表时间：
2016-08-01
影响因子：
2.4
通讯作者：
Braga, Aline Cabral
中科院分区：
文献类型：
--
作者：
Lobo, Jorge A.;Ramos, Davi De Lacerda;Braga, Aline Cabral
大型花卉展示有利于吸引授粉媒介和花粉的进出口。然而，大型花卉展示也有负面影响，例如增加同性受精、花粉折扣和花蜜/花粉强盗吸引力。花卉展示的大小可以用不同的尺度（例如花朵、花序或整个植物）来测量，这些尺度之一的变化可能会以不同的方式影响花卉游客的行为。此外，天然林的破碎化可能会影响花卉参观率和花卉访客行为。在本研究中，使用来自巴西中部热带草原的树种（Tabebuia aurea）花序的视频记录来研究花序和树尺度上的花展示尺寸对传粉者和花蜜盗贼访问花序的影响，每次访问接近的花朵数量，潜在传粉者和花蜜盗贼每朵花的访问次数，以及这些变量与花蜜程度的相互作用。景观干扰。花蜜产量根据花龄进行量化。尽管大型蜜蜂承担了大部分授粉任务，但金黄色椴树的花序上却有各种各样的花昆虫。其他蜜蜂和蜂鸟物种是高度活跃的花蜜强盗。花序大小的增加增加了传粉者对花序的访问率，而树上花序数量的增加降低了对花序和花的访问率。这种效应与城市环境密切相关，在城市环境中观察到花朵最多的树木。授粉蜜蜂（和花蜜强盗）会访问每个花序中的少数花朵，并集中访问一小部分可用的花朵，从而产生每个花序和每朵花的访问次数的过度分散分布。这种行为反映了优先访问花蜜供应量较多的幼花（包括花蕾）。
Large floral displays favour pollinator attraction and the import and export of pollen. However, large floral displays also have negative effects, such as increased geitonogamy, pollen discounting and nectar/pollen robber attraction. The size of the floral display can be measured at different scales (e.g. the flower, inflorescence or entire plant) and variations in one of these scales may affect the behaviour of flower visitors in different ways. Moreover, the fragmentation of natural forests may affect flower visitation rates and flower visitor behaviour. In the present study, video recordings of the inflorescences of a tree species (Tabebuia aurea) from the tropical savannah of central Brazil were used to examine the effect of floral display size at the inflorescence and tree scales on the visitation rate of pollinators and nectar robbers to the inflorescence, the number of flowers approached per visit, the number of visits per flower of potential pollinators and nectar robbers, and the interaction of these variables with the degree of landscape disturbance. Nectar production was quantified with respect to flower age. Although large bees are responsible for most of the pollination, a great diversity of flower insects visit the inflorescences of T.aurea. Other bee and hummingbird species are highly active nectar robbers. Increases in inflorescence size increase the visitation rate of pollinators to inflorescences, whereas increases in the number of inflorescences on the tree decrease visitation rates to inflorescences and flowers. This effect has been strongly correlated with urban environments in which trees with the largest floral displays are observed. Pollinating bees (and nectar robbers) visit few flowers per inflorescence and concentrate visits to a fraction of available flowers, generating an overdispersed distribution of the number of visits per inflorescence and per flower. This behaviour reflects preferential visits to young flowers (including flower buds) with a greater nectar supply.