Phenotypic Plasticity, Ecophysiology, and Climate Change Loren Albert Image: Holeinthedonut.com Processes contribute to the fit between an organism and its environment. What is plasticity? Examples Limitations to plasticity: Valladares et al. 2007 Ecophysiological and Morphological responses to light : Valladares et al. 2000 Methodology: Coleman et al. 1994 Discussion 1
Species fit their environment But what happens when the habitat changes? Habitat Tracking Ackerly 2003 2
Evolution Plasticity 3
Extinction (maybe local, maybe not) Definition of plasticity An individual genotype assumes particular characteristics in a given environment. In a second environment it may remain the same, or it may be different. The amount by which the expressions of individual characteristics of a genotype are changed by different environments is a measure of plasticity of these characters. Plasticity is therefore shown by a genotype when its expression is able to be altered by environmental influences. Bradshaw 1965 4
From Sultan, 2007 Sun and Shade leaves Taiz and Zeiger. Plant Physiology. 2006. 5
Atkin et al. 2006 Reaction norm 5 No plasticity Plasticity Phenotype 4 3 2 1 0 Environment 6
Valladares et al. 2007 Index: (max min)/max 7
Constraints on plasticity imposed by biotic factors (fig 4) No herbivory=continuous line, herbivory= dotted line 8
Valladares et al. 2000 Recap Sixteen species of same genus (six gap species and ten shade species) Three light tteat treatments e ts(simulating understory, small gaps, and large gaps) Measured leaf mass per unit area leaf area ratio supporting biomass root:shoot ratio photosynthetic capacity dark respiration relative growth rate 9
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Coleman et al. 1994 ontogenetic drift : changes in plant traits over the course of plant growth and development. Design your studies so that comparisons address your study questions. 14
High CO2, closed circles. Low CO2, open circles 15
Discussion questions What is the importance of phenotypic plasticity in species responses to climate change relative to other processes (i.e. evolution, habitat tracking, etc)? What are some likely limits to plasticity in tropical forests? Is there anything special about tropical forests in this regard? Which traits would you hypothesize may be most plastic in tropical forests? Which potentially plastic traits would you hypothesize are most important for buffering forests against climate change? Additional References Ackerly, DD, 2003. Community assembly, niche conservatism, and adaptive evolution in changing environments. J. Plant Sci 164: S165 S184. S184 Atkin OK, Loveys BR, Atkinson LJ, Pons TL. 2006. Phenotypic plasticity and growth temperature: understanding interspecific variability. Journal of Exerimental Botany 57: 267 281. Bradshaw AD. 1965. Evolutionary significance of phenotypic plasticity in plants. Advances in Genetics 13: 115 155. Gaston KJ, et al. 2009. Macrophysiology: A Conceptual Reunification. American Naturalist. 174(5) 595 612. Lortie CJ and Aarssen LW. 1996. The specialization hypothesis for phenotypic plasticity in plants. Int. J. Plant Sci. 157(4):484 487. Pigliucci, M. 2001. Phenotypic plasticity: beyond nature and nurture. JHU Press. 16