Bryological and Lichenological Section/ABLS
Rice, Steven K. , Hanson, David T. , Aclander, Lynn .
Functional traits of Sphagnum moss canopies as they relate to photosynthetic performance evaluated using phylogenetically independent contrasts.
PHOTOSYNTHETIC characteristics vary greatly among species in the bryophyte genus Sphagnum. To understand how differences in plant tissue- and canopy-level traits contribute to that variation, we undertook a broad comparative study. Five species pairs from different taxonomic sections were collected and grown in a common greenhouse environment. Species pairs included S. magellanicum and S. portoricense, S. fallax and S. recurvum, S. contortum and S. lescurii, S. squarrosum and S. teres, and S. girgensohnii and S. tenerum. Quantum efficiency (Φ) and light saturated rate of photosynthesis (Amax) were estimated from photosynthetic light response curves obtained from 7.5 cm dia. samples of intact canopies. These parameters were compared with each other and with attributes that should influence the ability of a canopy to utilize light energy and included: vertical distribution of biomass, pigments, rubisco and nitrogen; tissue specific density; surface roughness; and canopy light transmittance. Correlations were performed using phylogenetically independent contrasts to reduce the effects of shared evolutionary history. Results indicate that Φ and Amax have diversified independently and are associated with unique changes in tissue allocation and canopy-level properties. For example, Φ is positively correlated with canopy light transmittance, whereas Amax is a positive function of tissue specific density. Consequently, photosynthetic variation within Sphagnum reflects significant evolutionary convergence and relates to patterns of adaptive ecological diversification.[c.e.:srb]
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1 - Union College, Department of Biology, Schenectady, New York, 12308, USA
2 - University of New Mexico, Department of Biology, 167 Castetter Hall, Albuquerque, New Mexico, 87131, USA
Presentation Type: Oral Paper:Papers for Sections
Date: Wednesday, August 2nd, 2006
Time: 8:30 AM