Print PageThe rich knowledge of internal biology accumulated for Arabidopsis thaliana makes it a wonderful tool for fundamental research in ecology and evolution. Knowledge of the ecology of A. thaliana unfortunately lags far behind knowledge of its internal biology, making interpretation of the meaning of functional genomic diversity difficult. We report here on a developing system for the study of the functional diversification that adapts A. thaliana to variation in climate. We collected seed from seventeen populations of A. thaliana in NE Spain and we census germination timing, growth, survival, developmental timing and reproduction in their source populations . Three growth chamber experiments illuminate adaptive strategies associated with temperature and moisture variation across the climate range of A. thaliana.
Results/Conclusions
The study describes a cline in which plants from cooler and wetter elevations grow more in the fall, less in the winter and more in the spring compared to plants from hotter dryer elevations, when all populations are grown in a common environment simulating mid-elevation climate. In addition low elevation plants allocate more of their mass to roots, and flower and fruit earlier than high elevation plants. In this experiment, plants from mid-elevation perform best in mid-elevation conditions. However, when grown in a simulated low elevation climate with cool moist winter and hot dry spring, low elevation plants perform best and significant clines are associated with climate of origin for allocation, developmental timing and photosynthesis/gas exchange traits. Finally we performed a factorial water supply and temperature experiment in which Spanish and Italian genotypes from short spring, hot-dry climates were compared to Spanish and Swedish populations from long spring, cool-moist climates. Populations differed signficantly in heat shock protein responses, up-regulating under both heat and drought stress. Water use efficiency, measured as carbon isotope ratio, is highly plastic and populations both differed overall and showed contrasting responses to both water and temperature, but did not differ in response to the interaction of heat and water. Low elevation and latitude populations again allocated disproportionately to roots, which led to greater water use and lowered water use efficiency, but flowered and senesced earliest. Taken together, these results indicate substantial clines in functional aspects of biochemistry, development and allocation that suggest divergent strategies adapting plants across the climate range of this species.
