Alexander, Patrick J. .
Ecology of C3 and C4 photosynthesis in Arizona grasses (Poaceae): a phylogenetically-controlled analysis.
IT is accepted wisdom that plants with C3 and C4 photosynthesis segregate along precipitation and temperature gradients, with C4 plants in hotter and drier habitats. However, photosynthetic pathways are phylogenetically constrained and previous analyses have not been corrected for phylogeny. As a result the relationship between photosynthetic pathway and ecology may have been over-stated. When dealing with phylogenetically constrained traits, members of a clade do not give independent data, as similarity between members of a clade may simply represent phylogenetic inertia rather than resulting from the trait of interest. Corrections for the effect of phylogeny can be done by restricting comparisons to sister clades. I conducted a phylogenetically corrected analysis using the program Comparative Analysis via Independent Contrasts (CAIC) to test for a significant relationship between photosynthetic pathway and either temperature or rainfall among grasses occurring at six sites in the state of Arizona. This analysis used published phylogenies, collection information available online from the herbaria ARIZ, ASC, and ASU, and climatic data available through the Western Regional Climate Center. No significant relationships were found between photosynthetic pathway and ecological variables in this phylogenetically controlled analysis. A less geographically-restricted analysis is planned to ascertain if limitations in climatic variability or under-representation of C3 members of the subfamily Panicoideae in the current data may be confounding the analysis to give this rather surprising result.[c.e.:srb]
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1 - New Mexico State University, Department of Biology, Po Box 30001, Department 3Af, Las Cruces, New Mexico, 88003-8001, USA
Presentation Type: Poster:Posters for Sections
Location: Auditorium/Bell Memorial Union
Date: Tuesday, August 1st, 2006
Time: 12:30 PM