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40546-AC8
Why do Leaves Have Teeth? Breakthroughs in Paleoclimate Analysis from the Biological Understanding of Leaf Shape
Work under this grant has strongly impacted the research activities of both the PI and post-doc (Royer, who is now in a tenure-track position at Wesleyan University). This report outlines ongoing and future work that this grant has stimulated.
Firstly, the methods generated under this grant have been recently applied to three Eocene fossil plant localities. This work represents the first application of these methods to the fossil realm. The fossil results have both confirmed the usefulness of the methods and have further suggested that phylogenetic history may be an important confounding variable in some cases. This project constituted a Master's thesis (Cariglino 2007) and is currently in preparation for publication (Cariglino et al., in prep). Several other fossil floras, include a suite of floras across the Paleocene-Eocene thermal maximum, are currently being analyzed by Royer and colleagues.
Second, work under this grant has directly led to the development of a new fossil proxy for leaf mass per area. Leaf mass per area is a critical ecological variable that provides information about how quickly or slowly a plant is turning over its nutrient resources. This project was developed in collaboration with 15 co-authors from five countries and will be published later this year (Royer et al., 2007), and subsequent work has applied this method to another fossil suite (Currano et al., in review).
Third, Royer is now expanding the calibration data set that was collected under this grant. Most importantly, Royer has recently submitted (June 2007) an NSF proposal to facilitate a significant expansion (70 sites vs. the current 20). This proposed work will improve the existing method for reconstructing mean annual temperature, create a new method for reconstructing mean annual precipitation, and directly address the potential confounding influence of phylogeny.
Work under this grant has led to other projects related to leaf teeth. For example, we have recently completed a study that tracked the sensitivity of leaf size and shape to climate within two species (California black oak and red maple) (Royer et al., in prep). We are also nearly completed with a project that involves quantifying the sensitivity of leaf teeth to a moisture gradient and a suite of ecological gradients in eastern Australia (Royer et al., in prep).
In summary, this grant has either directly supported or facilitated at least seven research projects, eight peer-reviewed publications (including in late stage of preparation), and twelve conference abstracts. Both the PI and post-doc continue to work on projects that either began as or were inspired from work under this grant.
