Long & Medium-Term Research: Evolutionary Genetics of Host Plant Choice in a Willow Leaf Beetle. This award recommendation is made under the Program for Long & Medium-Term Research at Foreign Centers of Excellence. The program seeks to enable U.S. scientists and engineers to conduct long-term research abroad at research institutions of proven excellence. Awards provide opportunities for the conduct of joint research, and the use of unique or compli- mentary facilities, expertise and experimental conditions in foreign countries. This award will support a twelve-month visit by Dr. Nathan Rank to both Belgium and Switzerland, to work with Dr. Jacques Pasteels, Universit Libre de Bruxelles, and Dr. Martine Rowell-Rahier, Zoologisches Institut der Universitaet Basel, on "Evolutionary Genetics of Host Plant Choice in a Willow Leaf Beetle." In order better to understand the evolutionary consequences of host shifts in insects, the principal investigator proposes to complete a study of the relationship between regional variation in host use and genetic divergence in a willow leaf beetle, Phratora vitellinae (Coleoptera: Chrysomelidae), common throughout Eurasia, which is known to vary hosts regionally. Willow beetles in general have a highly subdivided population structure, with measurable genetic differentiation at even small spatial scales. Since P. vitellinae has the regional variation in preference and a subdivision population structure, it will provide an excellent model for this study. Building on his previous work on the population structure of a North American willow leaf beetle and Prof. Rowell-Rahier's research on regional variation in P. vitellinae's host plant use, the principal investigator will ask: 1) How do insects evolve preferences for new host plant species?, and 2) Do insects form genetically differen- tiated host races when they accomplish a host shift? To answer these, he will: 1) Use electrophoretic markers to measure P. vitellinae's population structure and to determine whether populations are differentiated along host species lines; and 2) Conduct a genetic analysis of host plant preferences. The experimental protocol will include 1) quantification of genetic variation within populations in preference and 2) determination of the mode of inheritance of preference by crossing populations which show regional variation in preference. Because the principal investigator will use the same P. vitellinae populations for the electrop- horetic study and the genetic analysis, he will be able to relate variations in host use directly with patterns of genetic differentiation.
