Department of Biosciences, College of Science, Swansea University, Swansea, UK.
School of Medicine, Institute of Life Science, Swansea University, Swansea, UK.
J Anim Ecol. 2018 Jul;87(4):1008-1021. doi: 10.1111/1365-2656.12828. Epub 2018 Apr 16.
Pollination by insects is a key ecosystem service and important to wider ecosystem function. Most species-level pollination networks studied have a generalised structure, with plants having several potential pollinators, and pollinators in turn visiting a number of different plant species. This is in apparent contrast to a plant's need for efficient conspecific pollen transfer. The aim of this study was to investigate the structure of pollen transport networks at three levels of biological hierarchy: community, species and individual. We did this using hoverflies in the genus Eristalis, a key group of non-Hymenopteran pollinators. We constructed pollen transport networks using DNA metabarcoding to identify pollen. We captured hoverflies in conservation grasslands in west Wales, UK, removed external pollen loads, sequenced the pollen DNA on the Illumina MiSeq platform using the standard plant barcode rbcL, and matched sequences using a pre-existing plant DNA barcode reference library. We found that Eristalis hoverflies transport pollen from 65 plant taxa, more than previously appreciated. Networks were generalised at the site and species level, suggesting some degree of functional redundancy, and were more generalised in late summer compared to early summer. In contrast, pollen transport at the individual level showed some degree of specialisation. Hoverflies defined as "single-plant visitors" varied from 40% of those captured in early summer to 24% in late summer. Individual hoverflies became more generalised in late summer, possibly in response to an increase in floral resources. Rubus fruticosus agg. and Succisa pratensis were key plant species for hoverflies at our sites Our results contribute to resolving the apparent paradox of how generalised pollinator networks can provide efficient pollination to plant species. Generalised hoverfly pollen transport networks may result from a varied range of short-term specialised feeding bouts by individual insects. The generalisation and functional redundancy of Eristalis pollen transport networks may increase the stability of the pollination service they deliver.
昆虫传粉是一种关键的生态系统服务，对更广泛的生态系统功能很重要。大多数研究过的物种水平传粉网络具有广义结构，植物有几个潜在的传粉者，而传粉者反过来又访问许多不同的植物物种。这与植物对同种花粉有效传递的需求明显相反。本研究的目的是在三个生物层次上调查花粉运输网络的结构：群落、物种和个体。我们使用 Eristalis 属的虻作为关键的非膜翅目传粉者来实现这一目标。我们使用 DNA metabarcoding 来识别花粉构建花粉运输网络。我们在英国威尔士西部的保护草原上捕获虻，去除外部花粉负荷，在 Illumina MiSeq 平台上使用标准的植物条形码 rbcL 对花粉 DNA 进行测序，并使用预先存在的植物 DNA 条形码参考库匹配序列。我们发现 Eristalis 虻从 65 种植物中运输花粉，比以前认为的要多。在地点和物种水平上，网络具有通用性，这表明存在某种程度的功能冗余，并且与初夏相比，夏末的网络更加通用。相比之下，个体水平上的花粉运输显示出一定程度的专业化。在初夏捕获的虻中，被定义为“单种植物访问者”的虻比例从 40%变化到夏末的 24%。个体虻在夏末变得更加通用，这可能是对花卉资源增加的反应。在我们的研究地点，悬钩子属和欧洲蕨是虻的关键植物物种。我们的结果有助于解决通用传粉者网络如何为植物物种提供有效传粉的明显悖论。广义虻花粉运输网络可能是由个体昆虫的一系列短期专门摄食行为引起的。Eristalis 花粉运输网络的概括性和功能冗余可能会增加它们提供的授粉服务的稳定性。
