Sutton Timothy L, Riegler Markus, Cook James M
Hawkesbury Institute for the Environment, Western Sydney University, Locked Bag 1797, Penrith, NSW, 2751, Australia.
Mol Ecol. 2016 Feb;25(4):882-94. doi: 10.1111/mec.13445. Epub 2016 Jan 18.
The structure of populations across landscapes influences the dynamics of their interactions with other species. Understanding the geographic structure of populations can thus shed light on the potential for interacting species to co-evolve. Host-parasitoid interactions are widespread in nature and also represent a significant force in the evolution of plant-insect interactions. However, there have been few comparisons of population structure between an insect host and its parasitoid. We used microsatellite markers to analyse the population genetic structure of Pleistodontes imperialis sp. 1, a fig-pollinating wasp of Port Jackson fig (Ficus rubiginosa), and its main parasitoid, Sycoscapter sp. A, in eastern Australia. Besides exploring this host-parasitoid system, our study also constitutes, to our knowledge, the first study of population structure in a nonpollinating fig wasp species. We collected matched samples of pollinators and parasitoids at several sites in two regions separated by up to 2000 km. We found that pollinators occupying the two regions represent distinct populations, but, in contrast, parasitoids formed a single population across the wide geographic range sampled. We observed genetic isolation by distance for each species, but found consistently lower FST and RST values between sites for parasitoids compared with pollinators. Previous studies have indicated that pollinators of monoecious figs can disperse over very long distances, and we provide the first genetic evidence that their parasitoids may disperse as far, if not farther. The contrasting geographic population structures of host and parasitoid highlight the potential for geographic mosaics in this important symbiotic system.
景观中种群的结构会影响它们与其他物种相互作用的动态过程。因此，了解种群的地理结构有助于揭示相互作用的物种共同进化的潜力。宿主 - 寄生蜂的相互作用在自然界中广泛存在，也是植物 - 昆虫相互作用进化中的一股重要力量。然而，昆虫宿主与其寄生蜂之间的种群结构比较却很少。我们使用微卫星标记分析了帝王榕小蜂（Pleistodontes imperialis sp. 1）的种群遗传结构，它是杰克逊港无花果树（Ficus rubiginosa）的一种榕果传粉黄蜂，以及其主要寄生蜂Sycoscapter sp. A在澳大利亚东部的情况。除了探究这个宿主 - 寄生蜂系统，据我们所知，我们的研究也是对一种非传粉榕小蜂种群结构的首次研究。我们在两个相距达2000公里的区域的多个地点收集了传粉者和寄生蜂的配对样本。我们发现占据这两个区域的传粉者代表不同的种群，但相比之下，寄生蜂在采样的广泛地理范围内形成了一个单一的种群。我们观察到每个物种都存在距离隔离，但发现与传粉者相比，寄生蜂不同地点之间的FST和RST值始终较低。先前的研究表明雌雄同株无花果的传粉者可以远距离扩散，我们提供了首个遗传学证据，证明其寄生蜂可能扩散得同样远，甚至更远。宿主和寄生蜂截然不同的地理种群结构凸显了这个重要共生系统中地理镶嵌体的潜力。
