S C OT T A . PAV E Y E T A L . results best support the scenario that migration was present be- tween these populations for a substantial period after divergence. However, because we do not estimate the distribution of actual migration events, only the average time of migration, we cannot compare the relative time periods of divergence with and without migration. By applying genetic analysis techniques to a system with known temporal landmarks based on documented volcanic erup- tions, we uncovered details of a case of very recent ecologi- cal divergence despite gene flow. This divergence began around 500 years or 100 generations before present. We measured migra- tion that occurred since divergence. To our knowledge, this is the most recent ecological divergence ever reported in a fish species following natural colonization. In this case, it appears that this ecological divergence occurred despite migration. ACKNOWLEDGMENTS We thank F. Breden, J. Hey, A. Mooers, C. Nice, P. Nosil, and three anonymous reviewers for comments on the manuscript. We thank the Evolution Discussion Group (FAB∗-Lab) at Simon Fraser University and the Vancouver Evolution Group (VEG) for critical discussions of this work. We thank E. Wang, M. McBurney, J.E. Krebs, B. Girard, K. Bunney, T. Tingey, J.L. Miller, J. Marcus, R. Rumelhart, and the Staff of Katmai National Park for field assistance. We thank R. Mackas for help with data entry and analysis. We thank W.D. Noon and J.L Miller for help with graphics. We thank I. Williams, S. Graziano, and G.K. Sage for help in the laboratory. This work was funded by the National Park Service, the U.S. Geological Survey, Alaska EPSCoR, National Science Foundation, University of Alaska Anchorage, and Natural Sciences and Engineering Research Council operating grant to F. Breden, Simon Fraser University. LITERATURE CITED Barluenga, M., K. N. Stolting, W. Salzburger, M. Muschick, and A. Meyer. 2006. 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