Tree Physiology Advance Access originally published online on July 2, 2009
Tree Physiology 2009 29(9):1133-1142; doi:10.1093/treephys/tpp046
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Genetic basis of aboveground productivity in two native Populus species and their hybrids
1 School of Forestry, Northern Arizona University, Flagstaff, AZ 86011, USA
2 The Evergreen State College, Olympia, WA 98505, USA
3 Corresponding author (fischerd{at}evergreen.edu)
4 Department of Ecology and Evolutionary Biology, University of Tennessee, Knoxville, TN 37919, USA
5 Department of Biological Sciences, Northern Arizona University, Flagstaff, AZ 86011, USA
6 Merriam Powell Center for Environmental Research, Northern Arizona University, Flagstaff, AZ 86011, USA
7 School of Natural Sciences and Sierra Nevada Research Institute, University of California, Merced, CA 95343, USA
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Abstract |
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Demonstration of genetic control over riparian tree productivity has major implications for responses of riparian systems to shifting environmental conditions and effects of genetics on ecosystems in general. We used field studies and common gardens, applying both molecular and quantitative techniques, to compare plot-level tree aboveground net primary productivity (ANPPtree) and individual tree growth rate constants in relation to plant genetic identity in two naturally occurring Populus tree species and their hybrids. In field comparisons of four cross types (Populus fremontii S. Wats., Populus angustifolia James, F1 hybrids and backcross hybrids) across 11 natural stands, productivity was greatest for P. fremontii trees, followed by hybrids and lowest in P. angustifolia. A similar pattern was observed in four common gardens across a 290 m elevation and 100 km environmental gradient. Despite a doubling in productivity across the common gardens, the relative differences among the cross types remained constant. Using clonal replicates in a common garden, we found ANPPtree to be a heritable plant trait (i.e., broad-sense heritability), such that plant genetic factors explained between 38% and 82% of the variation in ANPPtree. Furthermore, analysis of the genetic composition among individual tree genotypes using restriction fragment length polymorphism molecular markers showed that genetically similar trees also exhibited similar ANPPtree. These findings indicate strong genetic contributions to natural variation in ANPP with important ecological implications.
Keywords: aboveground net primary productivity, broad-sense heritability, ecosystem traits, genes-to-ecosystems, genetic similarity, growth rate constant
Received October 15, 2008; Accepted June 9, 2009
* Present address: 1696 Kepner Drive, Anchorage, AK 99504, USA.