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The core evolutionary drivers of integrative allometric phenotypes: A trait based approach to scaling plant form, function, and growth

University of Arizona, Tucson and the Santa Fe Institute, Santa Fe, New Mexico
le 18/03/2011 à 14:15

Résumé

Linking functional traits to plant growth is critical for scaling attributes of organisms to the dynamics of ecosystems and for understanding how selection shapes integrated botanical phenotypes. However, a general mechanistic theory showing how traits specifically influence carbon and biomass flux within and across plants is needed. In this talk, building on foundational work on relative growth rate recent work on functional trait spectra, and metabolic scaling theory, I will present a generalized trait-based model of plant growth. I will first present new insights into a general framework for the origin of botanical allometic relationships. This new work highlights the core evolutionary drivers that appear to have been fundamental in determining how physiological processes scale within and across plant species. Last, I will show how this scaling framework then provides a basis for a predictive trait-based model for plant growth. In agreement with a wide variety of empirical data, this model uniquely predicts how key functional traits interact to regulate variation in relative growth rate, the allometric growth normalizations for both angiosperms and gymnosperms, and the quantitative form of several functional trait correlations. The model also provides a general quantitative framework to incorporate additional leaf-level trait scaling relationships and hence to unite functional trait spectra with theories of relative growth rate, and metabolic scaling. As a unique test of the theory, I will show how it can be used to calculate carbon use efficiency. This often ignored trait, which may influence variation in relative growth rate, appears to be vary across plants and populations suggesting that it may be a key trait shaped by selection in order to mediate plant-environment interactions. Together, these results show how both quantitative plant traits and the geometry of vascular transport networks can be merged into a common scaling theory. It provides a framework for predicting not only how traits covary within an integrated allometric phenotype but also how trait variation mechanistically influences plant growth and carbon flux within and across diverse ecosystems.