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Updated: Dec 29, 2025

Relating Stomatal Conductance to Leaf Functional Traits
Published on: October 12, 2015
Links between environment and stomatal size through evolutionary time in Proteaceae
Gregory J Jordan1, Raymond J Carpenter1,2, Barbara R Holland3,4
1Discipline of Biological Sciences, University of Tasmania, Private Bag 55, Hobart, Tasmania 7001, Australia.
Plant stomatal size, crucial for CO2 uptake and water loss, evolved with climate. Fossil Proteaceae show stomatal size responded to temperature, not just CO2 levels, over 70 million years.
Area of Science:
- Paleobotany
- Evolutionary Biology
- Climate Science
Background:
- Stomatal size is evolutionarily significant, regulating gas exchange in plants.
- Understanding stomatal responses to past climate change is key to predicting future plant adaptations.
Purpose of the Study:
- To investigate the relationship between stomatal cell size and Cenozoic climate change using fossil Proteaceae.
- To determine if environmental factors beyond atmospheric CO2 influence stomatal evolution.
Main Methods:
- Analysis of fossil cuticles from Proteaceae, measuring guard cell length, pavement cell area, and stomatal index.
- Utilizing stochastic modeling to test trait evolution correlations.
- Integrating fossil data with published estimates of past temperature and atmospheric CO2.
Main Results:
- Guard cell length significantly increased, while stomatal density decreased with falling palaeotemperatures.
- Contrary to expectations, stomata were smaller and denser at higher atmospheric CO2 concentrations.
- Stomatal traits covaried, indicating coordinated development of leaf tissues.
Conclusions:
- Stomatal size in Proteaceae is significantly influenced by environmental factors other than atmospheric CO2.
- Evidence suggests complex interactions between climate variables and stomatal evolution over the Cenozoic.
- Coordinated development of leaf tissues plays a role in shaping stomatal traits.
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