Augustyn Willem J, Anderson Bruce, Ellis Allan G
Department of Botany and Zoology, University of Stellenbosch, Private Bag X1, Matieland 7602, South Africa.
J Anim Ecol. 2016 Jul;85(4):994-1003. doi: 10.1111/1365-2656.12536. Epub 2016 May 24.
Patterns of niche partitioning can result from local ecological interactions (e.g. interspecific competition) occurring within a contemporary time frame (realized niche partitioning). Alternatively, they may represent the end product of historical processes acting over long time frames (fundamental niche partitioning). Niche partitioning is often detected by analysing patterns of resource use within communities, but experiments are rarely conducted to test whether patterns of non-overlapping resource use reflect realized or fundamental niche partitioning. We studied a community of restio leafhoppers from the genus Cephalelus and their host plants, the Restionaceae (restios). We used network and experimental approaches to determine whether network modularity (a measure of niche partitioning within local communities) reflects fundamental or realized niche partitioning. Using a weighted modularity index for two party networks (e.g. insect-plant), we determined whether the network of this community is modular (i.e. consists of groups of species interacting strongly, with weak interactions between groups). We also aimed to identify specific Cephalelus - restio modules (groups). Using knowledge of module membership to design experiments, we tested whether Cephalelus species from two different modules, Cephalelus uncinatus and Cephalelus pickeri, prefer and perform better on restios from their own modules vs. restios from other modules. These experiments were performed under controlled conditions, eliminating the influences of competition and predation on host choices. The Cephalelus - restio community was modular, implying niche partitioning. Cephalelus also preferred and performed better on restios from their own modules in the absence of local contemporary factors. Most niche partitioning in the investigated Cephalelus community is not caused by local interactions, and thus, host use patterns represent fundamental niches. Our findings highlight the importance of understanding local community structure in the light of processes extrinsic to the local community context.
生态位划分模式可能源于当代时间框架内发生的局部生态相互作用（例如种间竞争）（实现的生态位划分）。或者，它们可能代表了长期作用的历史过程的最终产物（基础生态位划分）。生态位划分通常通过分析群落内资源利用模式来检测，但很少进行实验来测试非重叠资源利用模式是反映了实现的还是基础的生态位划分。我们研究了Cephalelus属的帚灯草叶蝉群落及其寄主植物帚灯草科（帚灯草）。我们使用网络和实验方法来确定网络模块化（局部群落内生态位划分的一种度量）反映的是基础生态位划分还是实现的生态位划分。使用两方网络（例如昆虫 - 植物）的加权模块化指数，我们确定了这个群落的网络是否模块化（即由相互强烈作用的物种组组成，组间相互作用较弱）。我们还旨在识别特定的Cephalelus - 帚灯草模块（组）。利用模块成员关系的知识来设计实验，我们测试了来自两个不同模块的Cephalelus物种，即Cephalelus uncinatus和Cephalelus pickeri，在来自它们自己模块的帚灯草上与来自其他模块的帚灯草相比，是否更喜欢且表现更好。这些实验在受控条件下进行，消除了竞争和捕食对寄主选择的影响。Cephalelus - 帚灯草群落是模块化的，这意味着存在生态位划分。在没有局部当代因素的情况下，Cephalelus也更喜欢来自它们自己模块的帚灯草并且表现更好。在所研究的Cephalelus群落中，大多数生态位划分不是由局部相互作用引起的，因此，寄主利用模式代表基础生态位。我们的研究结果强调了根据局部群落背景之外的过程来理解局部群落结构的重要性。
