title: A cline in seed dormancy helps conserve the environment experienced during reproduction across the range of Arabidopsis thaliana.
abstract: OBJECTIVE
  Understanding the factors shaping range limits is critical given current changes in climate as well as human-mediated introduction of species into novel environments. Phenological responses to climate influence range limits by allowing plants to avoid conditions that decrease population growth rates. Studying these processes is a challenge due to the joint contributions of both genetic and environmental variation to phenology.
  
  
  METHODS
  Using a previously developed model that predicts phenology of three dormancy "genotypes" in four locations spanning the European range of Arabidopsis thaliana, we examined how variation in seed dormancy influences the environmental conditions experienced by reproductive individuals and how those conditions influence reproductive potential. We calculated two metrics: temperature experienced during reproduction and the length of thermal window available for reproduction.
  
  
  RESULTS
  Seed dormancy levels determine whether a spring-flowering life cycle is expressed and thus determine the reproductive environment. A genetic cline in seed dormancy across the range reduces differences in reproductive environment and increases the thermal opportunity for reproduction before conditions become unfavorable for survival. Counter-intuitively, these putatively local genotypes are predicted to reproduce in slightly cooler conditions in the south than in the north, suggesting that maternal environmental effects on average could induce deeper dormancy in southern seeds reinforcing the observed genetic cline. However, within a location, we found large individual level differences.
  
  
  CONCLUSIONS
  Phenological adjustments of early life stages can contribute to the maintenance of consistent reproductive environments experienced by individual plants across ranges despite variable environmental conditions over time and space.
authors.affiliation: Department of Biology, Duke University, Box 90338 Durham, North Carolina 27708 USA liana.burghardt@gmail.com.
authors.forename: Liana T
authors.initials: LT
authors.lastname: Burghardt
authors.affiliation: Department of Ecology and Evolutionary Biology, Princeton University, Princeton, New Jersey 08544 USA.
authors.forename: C Jessica E
authors.initials: CJ
authors.lastname: Metcalf
authors.affiliation: Department of Biology, Duke University, Box 90338 Durham, North Carolina 27708 USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Donohue
mesh_terms: D000220:Adaptation, Biological; D017360:Arabidopsis / Q000235:genetics / Q000254:growth & development / Q000502:physiology*; D005060:Europe; D005838:Genotype; D008957:Models, Genetic; D057445:Plant Dormancy; D012098:Reproduction; D012639:Seeds / Q000254:growth & development
keywords: Arabidopsis thaliana; Brassicaceae; adaptation; habitat selection; life-cycle modeling; maternal temperature effects; phenology; phenotypic plasticity; range limits; reproductive timing; seed dormancy