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).
