Christian Lexer
clexer@indiana.edu

Indiana University
Department of Biology
Jordan Hall 325
Indiana University
Bloomington, IN 47405 USA

Advisors:
Dr. Loren Rieseberg, Program in Genetics, IU

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Research Interests

I am currently interested in the genetics of hybridization and speciation in wild sunflowers (Helianthus spp.). Within this project, I am using molecular approaches (microsatellites and AFLPs) to study the genetic architecture of a number of traits that are thought to be involved in hybridization and speciation processes, making use of synthetic hybrid lineages between Helianthus annuus (the predecessor of the cultivated sunflower) and Helianthus petiolaris (the prairie sunflower). I am also conducting field experiments to study the role of ecological divergence in the origin of Helianthus paradoxus, a hybrid species derived from H. annuus and H. petiolaris. Ultimately, I plan to connect these field experiments with molecular approaches to find out how ecology interacts with the genetics of speciation, i.e., how natural selection acts on specific genomic regions (QTLs) or even candidate genes involved in the origin of this sunflower hybrid species. I am also interested in potential applications of evolutionary genetics to more practical problems in agriculture and forestry, e.g. in improving conservation decisions or management practices in forestry, or in accelerating the breeding process in wild and hitherto undomesticated  species.

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Publications

• Lexer, C., R. A. Randell, and L. H. Rieseberg. 2002. Experimental hybridization as a tool for studying selection in the wild. Ecology. Special feature: Selection experiments for ecologists - concepts, methods, and directions, in press.
• Lexer, C, Heinze B, Gerber S, Macalka-Kampfer S, Steinkellner H, Ziegenhagen B, Kremer A, and J Gloessl (2001) Microsatellite analysis of small anonymous seed lot samples from pedunculate oak: a promising approach to monitor the number of different seed parents and pollen donors. In: Mueller-Starck G and Schubert, R (eds). Genetic response of forest systems to changing environmental conditions. Kluwer Academic Publishers, Dordrecht, The Netherlands.
• Widmer A, and Lexer C. (2001) Glacial refugia: sanctuaries for allelic richness, but not for gene diversity. TREE 16: 267-269.
• Lexer C, Heinze B, Gerber S, Macalka-Kampfer S, Steinkellner H, Kremer A, Glössl J (2000) Microsatellite analysis of maternal half-sib families of Quercus robur, pedunculate oak (II): inferring the number of pollen donors from the offspring. Theor Appl Genet 100: 858-865.
• Lexer C, Heinze B, Steinkellner H, Kampfer S, Ziegenhagen B, Glössl J (1999) Microsatellite analysis of maternal half-sib families of Quercus robur, pedunculate oak: detection of seed contaminations and inference of the seed parents from the offspring. Theor Appl Genet 99: 185-191.
• Streiff R, Ducousso A, Lexer C, Steinkellner H, Glössl J, Kremer A (1999) Pollen dispersal inferred from paternity analysis in a mixed oak stand of Quercus robur and Quercus petraea (Matt.) Liebl. Mol Ecol 8: 831-841.