Global Change Research Group, Institut Mediterrani d'Estudis Avançats (CSIC-UIB), Miquel Marqués 21, 07190, Esporles, Mallorca, Balearic Islands, Spain.
Centre for Ecology and Conservation, College of Life and Environmental Sciences, University of Exeter, Cornwall Campus, Penryn, TR10 9FE, UK.
Am J Bot. 2020 Jul;107(7):957-969. doi: 10.1002/ajb2.1499. Epub 2020 Jun 26.
Opportunistic nectar-feeders may act as effective pollinators; nonetheless, we still lack information on whether these opportunistic species differ in their pollination effectiveness from specialized nectarivorous vertebrates and insects. Many nectar specialists have coevolved with the plants on which they feed; therefore, we would expect higher pollination effectiveness in specialists than in opportunistic feeders. Here, we assessed quantity and quality components of pollination effectiveness in specialist and opportunistic vertebrate nectarivores and insects, focusing on three plants from the Seychelles: Thespesia populnea, Polyscias crassa, and Syzygium wrightii.
We determined the quantity component (QNC) of pollination effectiveness with pollinator observations, and the quality component (QLC) by measuring fruit and seed set resulting from single visits by each pollinator. To detect potential negative effects of invasive ants on native plant-pollinator interactions, we classified pollinator visits (quantity component) as disturbed (>6 ants/30 min) vs. undisturbed.
All focal plants were visited by insects, and vertebrate specialist and opportunist nectarivores, yet their pollination effectiveness differed. Flying insects were the most effective pollinators of T. populnea. The other two plants were most effectively pollinated by vertebrates; i.e., sunbirds (nectar specialists) in S. wrightii and Phelsuma geckos (nectar opportunists) in P. crassa, despite marked variation in QNC and QLC. Ant presence was associated with lower pollinator visitation rate in P. crassa and S. wrightii.
Our study highlights the importance of all pollinator guilds, including opportunist nectarivorous vertebrates as pollinators of island plants, and the vulnerability of such interactions to disruption by nonnative species.
机会主义的花蜜取食者可能是有效的传粉者；尽管如此，我们仍然缺乏关于这些机会主义物种在传粉效率方面是否与专门的花蜜取食脊椎动物和昆虫不同的信息。许多花蜜专家与它们所取食的植物共同进化；因此，我们预计专家的传粉效率会高于机会主义取食者。在这里，我们评估了专门的和机会主义的脊椎动物花蜜取食者和昆虫的传粉效率的数量和质量组成部分，重点研究了塞舌尔的三种植物：Thespesia populnea、Polyscias crassa 和 Syzygium wrightii。
我们通过观察传粉者来确定传粉效率的数量组成部分（QNC），并通过测量每个传粉者单次访问所产生的果实和种子数来确定质量组成部分（QLC）。为了检测入侵蚂蚁对本地植物-传粉者相互作用的潜在负面影响，我们将传粉者访问量（数量组成部分）分为受干扰（>6 只蚂蚁/30 分钟）和未受干扰。
所有有焦点的植物都被昆虫和脊椎动物专家和机会主义的花蜜取食者访问，但它们的传粉效率不同。飞行昆虫是 T. populnea 最有效的传粉者。另外两种植物则由脊椎动物最有效地传粉；即，太阳鸟（花蜜专家）在 S. wrightii 中，而 Phelsuma 蜥蜴（花蜜机会主义者）在 P. crassa 中，尽管 QNC 和 QLC 存在明显差异。蚂蚁的存在与 P. crassa 和 S. wrightii 中传粉者访问率的降低有关。
我们的研究强调了所有传粉者群体的重要性，包括作为岛屿植物传粉者的机会主义的花蜜取食脊椎动物，以及这种相互作用易受非本地物种干扰的脆弱性。
