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Abstract Detail


Paleobotanical Section

Punyasena, Surangi W. [1].

The climatic optimization of plant families and the reconstruction of paleoenvironments: A probabilistic approach to estimating paleotemperature and paleoprecipitation in the Neotropics.

One of the presumed limitations of using higher-level taxonomic groups in reconstructing climate has been the assumption that the diagnostic relationship between plants and climate lies only at the species level. Sister species, particularly in the tropics, are often found in very different habitats. This demonstrated ecophysiological diversity should confound familial generalizations. However, the results of a nearly continent-scale meta-analysis of Neotropical vegetation indicate otherwise. Even at the taxonomic resolution of the plant family, the abundance of widespread and ecologically important taxa, including Fabaceae, Melastomataceae, Bignoniaceae, and Arecaceae, display clear covariation with temperature and precipitation gradients. The first-order pattern is with relatively small temperature differences, while the second-order pattern is with precipitation.
Given that plant families do have climatic optima, a niche-based model of spatial distributions can be used to reconstruct paleoclimate. Using published data on the spatial abundance distributions of 155 plant families, I constructed a probabilistic model of temperature and precipitation. A limited number of published pollen surface samples (representing contemporary lowland vegetation) were used to test the accuracy of the climatic estimates. The model was then applied to published palynological data from two Quaternary cores from northeastern Bolivia, reconstructing temperature and precipitation for the last 40,000 years. The results demonstrate clear cooling (~2°C) and intermittent drying in lowland Bolivia during the glacial interval.
Family-based climatological proxies have several advantages over biome-based reconstructions. Climatic estimates can be derived even when novel combinations of taxa are observed in the fossil record, extending the utility of the model to deep-time paleobotanical data. The model is also dynamic. Plant communities do not need to be in equilibrium and individualistic, Gleasonian dynamics can be incorporated into estimates. Finally, the model provides working hypotheses of how individual species may respond to climatic change based on the climatic specialization of its family.


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1 - The University of Chicago, Committee on Evolutionary Biology, 1025 East 57th Street, Culver 402, Chicago, IL, 60637, USA

Keywords:
paleoclimate proxy
Neotropics
temperature
precipitation
family
kernel density.

Presentation Type: Oral Paper:Papers for Sections
Session: CP11
Location: Williford A/Hilton
Date: Monday, July 9th, 2007
Time: 12:00 PM
Number: CP11008
Abstract ID:1776


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