Avila R, Pinheiro M, Sazima M
Laboratório de Estudos em Biodiversidade Pampiana, LEBIP, Universidade Federal do Pampa, Campus São Gabriel, Rio Grande do Sul, Brasil.
Plant Biol (Stuttg). 2015 May;17(3):728-33. doi: 10.1111/plb.12291. Epub 2015 Jan 27.
Inga species are characterised by generalist or mixed pollination system. However, this feature does not enhance reproductive rates in species with very low fruit set under natural conditions. Some ecological and genetic factors are associated with this feature, and to test the effect of massive visits on pollination success in Inga subnuda subsp. luschnathiana, we studied the efficacy of polyads deposited on stigmas of flowers isolated from visitors and polyads exposed to visitors. The proportion of polyads fixed in stigmas decreased after exposure to visitors (24 h) in comparison to stigmas isolated from visitors (hummingbirds, bees, wasps, hawkmoths and bats), and fruit set was very low. Furthermore, nectar production, sugar composition and other floral biology traits were evaluated. Increased nectar production, sugar availability and sucrose dominance during the night indicates adaptation to nocturnal visitors and supports their role as main pollinators; although the brush-flower morphology, time of anthesis, nectar dynamics and chemical composition also allow daytime visitors. Thus the species is an important resource for a diverse group of floral visitors. We conclude that excess visits (diurnal and nocturnal) are responsible for the decrease in fixed polyads in stigmas of I. subnuda subsp. luschnathiana flowers, thus contributing, with others factors, to its low fruit set. Therefore, the generalist pollination system does not result in reproductive advantages because the low fruit set in natural conditions could be the result of a negative effect of visitors/pollinators.
印加属植物具有泛化或混合授粉系统的特征。然而，在自然条件下，这种特征并不会提高座果率极低的物种的繁殖率。一些生态和遗传因素与这一特征相关，为了测试大量访花者对卢氏南美柴桂亚种授粉成功率的影响，我们研究了放置在与访花者隔离的花朵柱头上的花粉团以及暴露于访花者的花粉团的有效性。与与访花者（蜂鸟、蜜蜂、黄蜂、天蛾和蝙蝠）隔离的柱头相比，暴露于访花者（24小时）后，固定在柱头上的花粉团比例下降，座果率非常低。此外，还评估了花蜜产量、糖分组成和其他花生物学特征。夜间花蜜产量增加、糖分可利用性增加以及蔗糖占主导地位，表明该物种适应夜间访花者，并支持它们作为主要传粉者的作用；尽管其刷状花形态、开花时间、花蜜动态和化学成分也适合白天的访花者。因此，该物种是多种访花者的重要资源。我们得出结论，过多的访花（白天和夜间）导致了卢氏南美柴桂亚种花朵柱头上固定花粉团数量的减少，因此与其他因素一起导致了其低座果率。所以，泛化授粉系统并不会带来繁殖优势，因为自然条件下的低座果率可能是访花者/传粉者负面影响的结果。
