Creese, Chris , Maherali, Hafiz .
Adaptation to Temperature and Correlated Evolution in Pines.
Identifying physiological traits undergoing correlated evolution and their relationship to climate is a critical step toward unraveling the mechanisms driving whole-plant adaptive strategies. To test adaptive hypotheses of trait-trait and trait-environment relationships, comparative studies with broad taxonomic sampling are useful but can be confounded by large differences in structure-function across taxa. Therefore, we targeted our study to a single genus, Pinus. Pines are the most speciose modern conifer genus and are widely distributed from the taiga to the tropics, providing ample opportunity for the evolution of disparate physiological strategies in response to differences in temperature and precipitation. Sampling 26 Pinus species grown in common garden, we tested for correlated evolution and adaptation to climate among hydraulic and growth-related traits using standard and phylogenetically independent contrast correlations. Significant negative relationships between wood density and stem and leaf hydraulic conductivity support a safety versus efficiency trade-off, which scales with plant size. Relative leaf area and biomass also negatively correlate with wood density, implying a cost of cavitation resistance to net photosynthetic area. However, trees with low leaf area had higher leaf N content, which may compensate for negative effects of reduced leaf area on whole-plant photosynthesis. Results also demonstrate a strong impact of temperature (and latitude) on growth, biomass allocation and hydraulics and suggest that pines are adapted to avoid drought rather than tolerate it. Given the impact of temperature on the evolution of pine functional traits, responses to global climate shifts may substantially alter pine distributions.
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1 - University of California Los Angeles, Ecology and Evolutionary Biology, 621 Charles E. Young Drive South, Box 951606, Los Angeles, CA, 90095-1606, United States
2 - University of Guelph, Integrative Biology, New Science Complex, 50 Stone Rd. East, Guelph, Ontario, N1G 2W1, Canada
adaptation to climate
Presentation Type: Oral Paper:Papers for Topics
Date: Monday, July 28th, 2008
Time: 2:45 PM