Influence of Rainfall and Geography on Leaf Size and Shape: Implications for Paleoclimatic Interpretation

降雨和地理对叶片大小和形状的影响：对古气候解释的启示植物的叶片受其环境的强烈影响。因此，几十年来，树叶化石的大小和形状（地貌）一直被用来重建古代陆地景观的气候和生态条件，这一点也不奇怪。PI及其同事开发了一种新的方法，称为数字叶片面相，与现有方法相比，该方法有望显著改善古环境重建。然而，目前的数字叶片地貌有两个根本性的缺点：目前的校准是基于有限的地理范围和有限的降雨范围。这限制了该方法的普遍适用性。本提案旨在测试气候（温度和降雨）如何影响不同地理环境下的叶片面相，使用数字叶片面相方法。研究结果将用于构建多变量模型，用于从化石植物区系中估计温度和降雨量，该模型比所有现有的古植物学方法都更准确。这些模型将应用于怀俄明州大角盆地的一系列化石区系，以量化整个古新世的气候。始新世热极大期（PETM）：地球系统历史上的一个关键时期。本提案将：(1)检验降雨对与气候有机械联系的地貌变量的影响；这些数据将有助于构建新的气候代用指标，并为理解叶片地貌的功能生态学提供更丰富的框架。(2)测定叶片的电位差异。不同地理环境下的气候关系；该试验将加强气候代理，有助于理解系统发育与环境对叶片外形的相对影响。(3)重建整个PETM的气候；尽管对始新世世热时期降雨的解释存在争议，但它对于理解化石土壤的碳同位素记录和始新世热的近因至关重要。根据这一建议，将建立一个树叶图像和相关面相和环境数据的网络数据库；这将作为公众的教育资源，并作为研究人员在本项目范围之外的方式整合树叶图像和面相数据的数据源。这项提案将资助8？卫斯理大学的14名本科生研究人员，卫斯理大学主要是本科生机构，这项提案的结果将被纳入卫斯理大学的课程。

INFLUENCE OF RAINFALL AND GEOGRAPHY ON LEAF SIZE AND SHAPE:IMPLICATIONS FOR PALEOCLIMATIC INTERPRETATIONThe leaves of plants are strongly affected by their environment. It is no surprise, then, that the size and shape (physiognomy) of fossil leaves have been used for many decades to reconstruct climatic and ecological conditions of ancient terrestrial landscapes. A new method, called digital leaf physiognomy, has been developed by the PI and colleagues that shows promise for significantly improving paleoenviromental reconstructions compared to existing approaches. However, digital leaf physiognomy presently has twofundamental shortcomings: the current calibration is based on sites with a limited geographic extent and a limited range in rainfall. This restricts the general applicability of the method. This proposal aims to test how climate (both temperature and rainfall) impacts leaf physiognomy in a diverse number of geographic settings using the digital leaf physiognomy approach. Results will be used to construct multivariate models for estimating temperature and rainfall from fossil floras that are more accurate than all existing paleobotanical methods. The models will be applied to a sequence of fossilfloras in the Bighorn Basin, Wyoming, to quantify climate across the Paleocene?]Eocene Thermal Maximum (PETM), a critical interval in Earth system history.This proposal will: (1) Test the influence of rainfall on physiognomic variables that have been mechanistically linked to climate; these data will facilitate the construction of new climate proxies and provide a richer framework for understanding the functional ecology of leaf physiognomy. (2) Test potential differences in leaf?]climate relationships in different geographic settings; this test will strengthen the climate proxies andcontribute towards understanding the relative influences of phylogeny vs. environment on leaf physiognomy. (3) Reconstruct climate across the PETM; the interpretation of rainfall during the PETM is contentious, yet it is essential for understanding carbon isotope records from fossil soils and the proximal causes of the PETM. Under this proposal, a web data bank for leaf images and associated physiognomic and environmental data will be created; this will serve as an educational source for the general public and as a data source for researchers incorporating leaf images and physiognomic data in ways outside the scope of this project. This proposal will fund 8?]14 undergraduate researchers at Wesleyan, a primarily undergraduate institution, and results from this proposal will be incorporated into Wesleyan courses.