Submitted on September 11, 2008
Accepted on November 19, 2008

Effects of Genetic Perturbation on Seasonal Life History Plasticity

¹ Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.
² Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA.
³ Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.; Present address: Biology Institute, Universidad de Antioquia, Medellin AA 1226, Colombia.
⁴ Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.; Present address: Department of Natural Resources, Cornell University, Ithaca, NY 14853, USA.
⁵ Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.; Present address: Department of Biology, Indiana University, Bloomington, IN 47405, USA.
⁶ Department of Agronomy, Kansas State University, Manhattan, KS 66506, USA.; Present address: Department of Biological Sciences, University of Notre Dame, Notre Dame, IN 46556, USA.
⁷ Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.; Present address: Huck Institutes of the Life Sciences, Pennsylvania State University, University Park, PA 16802, USA.
⁸ Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.; Present address: Department of Botany, University of British Columbia, Vancouver, BC V6T 1Z4, Canada.
⁹ Department of Ecology and Evolutionary Biology, Brown University, Providence, RI 02912, USA.; Present address: Department of Biology, University of Vermont, Burlington, VT 05405, USA.
¹⁰ Max Planck Institute for Plant Breeding Research, Cologne D-50829, Germany.

^* To whom correspondence should be addressed.
Johanna Schmitt , E-mail: johanna_schmidt{at}brown.edu

Like many species, the model plant Arabidopsis thaliana exhibits multiple different life histories in natural environments. We grew mutants impaired in different signaling pathways in field experiments across the species’ native European range in order to dissect the mechanisms underlying this variation. Unexpectedly, mutational loss at loci implicated in the cold requirement for flowering had little effect on life history except in late summer cohorts. A genetically informed photothermal model of progression toward flowering explained most of the observed variation and predicted an abrupt transition from autumn flowering to spring flowering in later summer germinants. Environmental signals control the timing of this transition, creating a critical window of acute sensitivity to genetic and climatic change that may be common for seasonally regulated life history traits.