IRFP: Elucidating Incipient Coevolutionary Speciation Through Experimental and Transcriptomic Approaches

国际研究奖学金计划使美国科学家和工程师能够在国外进行9到24个月的研究。该项目的奖项提供了联合研究的机会，并提供了使用国外独特或互补的设施、专业知识和实验条件的机会。该奖项由国际科学与工程办公室和环境生物学分部的进化生态学计划共同资助。该奖项将支持戴维·H·亨布里博士与日本大津京都大学的川下敦博士合作的为期18个月的研究奖学金，以及亨布里博士与加州大学伯克利分校的迈克尔·B·艾森博士合作的为期6个月的研究奖学金。物种间的共同进化在地球生物多样性中的作用是进化生物学的主要问题之一。特别是，有证据表明，处于互惠关系中的物种之间的共同进化(其中两个物种的成员都受益)促进了多样性，以及可能实现这一点的机制，这些证据仍然不明确。长期以来，昆虫和植物之间特别是无花果和无花果黄蜂以及丝兰和丝兰蛾之间的授粉互作一直被用作这项研究的模型，因为传粉者在运输寄主配子方面所起的作用使它们特别可能成为共同进化多样化的候选对象。然而，从经验和理论的角度来看，在这些系统中共同进化驱动多样性的证据都是模棱两可的，而且很少有研究明确地研究这些系统中的物种形成。本提案的目标是结合实验和转录切割方法来研究一个假定的情况，即在最近在法属波利尼西亚的海洋岛屿上多样化的一种特殊的昆虫-植物互惠关系中，新生的共同进化物种形成。叶蛾(鳞翅目：小蛾科：表头蛾)是其叶寄主植物的唯一传粉者。叶下珠：叶下珠，S，L。[Glochidion])，但它们的幼虫会消耗寄主种子的一部分，以换取授粉服务。这个项目将询问是否存在促进这种互惠专门化的机制，这种专门化是否会导致授粉者的种群分化，以及在这种互惠专门化的同时，基因表达或基因组序列方面的哪些差异正在演变。这些问题将通过生物分析、花香分析(GC-MS)、种群遗传学和转录组学等方法相结合来解决。在此过程中，这项研究将明确研究共同进化生物之间新生的共同进化物种形成，以及这种新生物种形成发生的机制。了解导致生物多样性的机制，特别是在热带地区，对于保护物种多样性和相互作用多样性至关重要。这项研究在这方面具有长期价值和短期价值，因为叶下珠是南太平洋主要的特有植物辐射之一，许多稀有物种受到入侵物种和栖息地破坏的威胁。此外，转录组学在昆虫寄主-小种形成研究中的应用具有明显的农业应用。该计划将促进首席研究人员在进化生物学的下一代测序方法方面的培训，以及他的国际研究经验。最后，该项目将促进日本京都大学(川下敦博士、加藤真本博士、冈本友子博士和藤户广子博士)、日本京都市立大学(大岛一井博士)、加州大学伯克利分校(Michael Eisen博士)和法属波利尼西亚理查大学(Jean-Yves Meyer博士)的首席研究员和研究小组之间的国际合作。

The International Research Fellowship Program enables U.S. scientists and engineers to conduct nine to twenty-four months of research abroad. The program's awards provide opportunities for joint research, and the use of unique or complementary facilities, expertise and experimental conditions abroad. This award is co-funded by the Office of International Science and Engineering and by the Evolutionary Ecology Program in the Division of Environmental Biology. This award will support an eighteen-month research fellowship by Dr. David H. Hembry to work with Dr. Atsushi Kawakita at Kyoto University in Otsu, Japan, followed by a six-month research fellowship for Dr. Hembry to work with Dr. Michael B. Eisen at the University of California, Berkeley. The role of coevolution between species in the diversification of life on earth is one of the major questions in evolutionary biology. In particular, evidence that coevolution between species in mutualistic relationships (in which members of both species benefit) promotes diversification, as well as the mechanisms by which it might do so, remains equivocal. Specialized pollination mutualisms between insects and plants, particularly those between figs and fig wasps and yuccas and yucca moths, have long been used as models for this research because the role that pollinators play in transporting their hosts' gametes makes them especially likely candidates for coevolutionary diversification. However, evidence for coevolution driving diversification in these systems is equivocal from both empirical and theoretical angles, and few studies have explicitly investigated speciation in these systems.The goal of this proposal is to use a combination of experimental and transcriptomic approaches to examine a putative case of nascent coevolutionary speciation in a specialized, insect-plant mutualism that has recently diversified on oceanic islands in French Polynesia. Leafflower moths (Lepidoptera: Gracillariidae: Epicephala) are the sole pollinators of their leafflower plant hosts (Phyllanthaceae: Phyllanthus s. l. [Glochidion]) but their larvae consume a subset of the host's seeds in return for the service of pollination. This project will ask whether mechanisms exist that promote reciprocal specialization in this mutualism, whether such specialization leads to population differentiation in the leafflower moth pollinators, and what kinds of differences in gene expression or genome sequence are evolving in tandem with this reciprocal specialization. These questions will be addressed through a combination of methods including bioassays, flower odor analysis (GC-MS), population genetics, and transcriptomics. In doing so, this study will explicitly investigate both nascent coevolutionary speciation between coevolving organisms, and the mechanisms by which such nascent speciation occurs.An understanding of the mechanisms that give rise to biodiversity, particularly in the tropics, is vital to conserving both species diversity and interaction diversity. This research has both long-term value and short term value in this regard, since Phyllanthus trees are one of the major endemic plant radiations in the South Pacific, with many rare taxa threatened by invasive species and habitat destruction. Additionally, the use of transcriptomics in the study of host-race formation in insects has clear agricultural applications. This program will facilitate the Principal Investigator's training both in next-generation sequencing methods in evolutionary biology, and his international research experience. Finally, this project will facilitate international collaboration between the Principal Investigator and research groups at Kyoto University, Japan (Dr. Atsushi Kawakita, Dr. Makoto Kato, Dr. Tomoko Okamoto, and Dr. Hirokazu Toju), Kyoto Prefectural University, Japan (Dr. Issei Ohshima), the University of California, Berkeley (Dr. Michael Eisen), and the Délégation à la Recherche, French Polynesia (Dr. Jean-Yves Meyer).