Integrative Ecology Group, Estación Biológica de Doñana, Isla de la Cartuja, Sevilla, Spain.
Oecologia. 2013 Sep;173(1):179-90. doi: 10.1007/s00442-013-2606-y. Epub 2013 Feb 13.
Ecologically isolated habitats (e.g., oceanic islands) favor the appearance of small assemblages of pollinators, generally characterized by highly contrasted life modes (e.g., birds, lizards), and opportunistic nectar-feeding behavior. Different life modes should promote a low functional equivalence among pollinators, while opportunistic nectar feeding would lead to reduced and unpredictable pollination effectiveness (PE) compared to more specialized nectarivores. Dissecting the quantity (QNC) and quality (QLC) components of PE, we studied the opportunistic bird-lizard pollinator assemblage of Isoplexis canariensis from the Canary Islands to experimentally evaluate these potential characteristics. Birds and lizards showed different positions in the PE landscape, highlighting their low functional equivalence. Birds were more efficient than lizards due to higher visitation frequency (QNC). Adult lizards differed from juveniles in effecting a higher production of viable seeds (QLC). The disparate life modes of birds and lizards resulted in ample intra- and inter-specific PE variance. The main sources of PE variance were visitation frequency (both lizards and birds), number of flowers probed (lizards) and proportion of viable seeds resulting from a single visit (birds). The non-coincident locations of birds and lizards on the PE landscape indicate potential constraints for effectiveness. Variations in pollinator abundance can result in major effectiveness shifts only if QLC is relatively high, while changes in QLC would increase PE substantially only at high QNC. The low functional equivalence of impoverished, highly contrasted pollinator assemblages may be an early diagnostic signal for pollinator extinction potentially driving the collapse of mutualistic services.
生态隔离的栖息地（例如海洋岛屿）有利于出现小型传粉者组合，这些组合通常具有鲜明对比的生活模式（例如鸟类、蜥蜴）和机会主义的花蜜取食行为。不同的生活模式应该会降低传粉者之间的功能等效性，而机会主义的花蜜取食行为与更专门的花蜜取食者相比，会降低和不可预测传粉效率 (PE)。为了剖析 PE 的数量 (QNC) 和质量 (QLC) 成分，我们研究了来自加那利群岛的 Isoplexis canariensis 的机会主义鸟类-蜥蜴传粉者组合，以实验评估这些潜在特征。鸟类和蜥蜴在 PE 景观中处于不同的位置，突出了它们的低功能等效性。由于访问频率更高，鸟类比蜥蜴更有效率（QNC）。成年蜥蜴在产生有活力种子的数量上（QLC）与幼体蜥蜴不同。鸟类和蜥蜴不同的生活模式导致了丰富的种内和种间 PE 差异。PE 差异的主要来源是访问频率（包括蜥蜴和鸟类）、探测花朵的数量（蜥蜴）和单次访问产生的有活力种子的比例（鸟类）。鸟类和蜥蜴在 PE 景观中的位置不一致表明有效性存在潜在限制。只有当 QLC 相对较高时，传粉者丰度的变化才会导致有效性的重大转变，而 QLC 的变化只有在 QNC 较高时才会显著增加 PE。贫瘠、高度对比的传粉者组合的低功能等效性可能是传粉者灭绝的早期诊断信号，这可能导致互惠服务的崩溃。
