phenotypic plasticity, ecophysiology, and climate change
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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?p y• Examples• Limitations to plasticity: Valladares et al. 2007•Ecophysiological and Morphological responses to light : Valladares et al 2000responses to light : Valladares et al. 2000•Methodology: Coleman et al. 1994•Discussion
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Species “fit” their environment
But what happens when the habitat changes?
Habitat Tracking
Ackerly 2003
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Evolution
Plasticity
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Extinction(maybe local, maybe not)
Definition of plasticity
“An individual genotype assumes particular characteristics in a given environment. In a gsecond 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
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From Sultan, 2007
Sun and Shade leaves
Taiz and Zeiger. Plant Physiology. 2006.
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Atkin et al. 2006
Reaction norm
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No plasticity Plasticity
0
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Phen
otype
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Environment
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Valladares et al. 2007
Index: (max‐min)/max
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Constraints on plasticity imposed by biotic factors (fig 4)
No herbivory=continuous line, herbivory= dotted line
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Valladares et al. 2000 Recap• Sixteen species of same genus (six gap species and ten shade species)
• Three light treatments (simulating understory, ee g t t eat e ts (s u at g u de sto y,small gaps, and large gaps)
• Measured – leaf mass per unit area– leaf area ratio– supporting biomassroot:shoot ratio– root:shoot ratio
– photosynthetic capacity– dark respiration – relative growth rate
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Coleman et al. 1994
• “ontogenetic drift”: changes in plant traits th f l t th dover the course of plant growth and
development.
• Design your studies so that comparisons address your study questions.
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High CO2, closed circles. Low CO2, open circles
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Discussion questions
• What is the importance of phenotypic plasticity in species responses to climate change relative to otherspecies 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?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 S184S165‐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.