Botany and Plant Pathology Seminar Series
Speaker: Dr. Doug Schemske - Department of Plant Biology - Michigan State University
Topic: Ecological genetics of adaptation in the model plant Arabidopisis thaliana
When: Wednesday, November 14, 2012 at 4:00pm in MJIS 1001

Understanding the ecological and genetic mechanisms of adaptation is one of the major goals of evolutionary biology. Key questions include: What ecological factors contribute to the form and magnitude of natural selection? What are the traits that confer adaptation? What is the genetic basis of adaptive traits? Are there adaptive tradeoffs? These are difficult questions, and it is perhaps not surprising that despite decades of research, we have few answers.

Our studies of the ecological genetics of adaptation in the model plant Arabidopsis thaliana involve native populations located near the northern (Sweden) and southern (Italy) limits of the natural range. Reciprocal transplant experiments carried out over five years demonstrate strong geographic adaptation, and lab experiments find evidence of large differences between populations in traits likely to have adaptive value (e.g., flowering time, freezing tolerance, dehydration tolerance, temperature-dependent photosynthetic acclimation). Field and lab studies using a new set of Recombinant Inbred Lines provide further information on the Quantitative Trait Loci (QTL) and traits involved in adaptation. We find that a relatively small number of QTL of moderate effect are involved in adaptation in this system. Furthermore, there is evidence of fitness trade-offs for some QTL, and the ecological mechanisms identified thus far suggest a trade-off between freezing tolerance and growth. Experiments are underway to identify the specific genes that contribute to the major fitness QTL.

Taken together, our results indicate that adaptation to different environments in Arabidopsis involves a surprisingly small number of QTL, and that the fitness effects at individual QTL can be substantial. This work adds to the growing evidence that adaptive evolution may often involve major genes.

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