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2000 Annual Science Report

Pennsylvania State University Reporting  |  JUL 1999 – JUN 2000

Timescale for the Early Evolution of Life on Earth: Molecular Evolutionary Approach - Hedges

Project Summary

The overall goal of research in this lab is to develop an accurate timescale for the evolution of life on Earth for comparison with Earth history (rise in oxygen, climate, plate tectonics, etc.). Such a synthesis will help to focus searches for life elsewhere. We use DNA and protein sequence data from the public databases and from sequences generated in the lab.

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Prokaryote evolution: We aligned sequences of over 300 genes from genome projects to examine the earliest divergences, and have been conducting phylogenetic and molecular clock analyses. Because of many apparent lateral transfer events, interpretation of phylogenies and analysis requires careful study. Chen and Watanabe are involved in this work. The results show the divergence of the last common ancestor was earlier than previously estimated but compatible with Earth’s geologic history. This work also involved some revision of statistical methods. A manuscript is being prepared. Eukaryote evolution: We estimated divergence times for major lineages of protists, fungi, animals, and plants. Of particular interest is the finding that fungi are much older than previously thought, with major groups originating 1.5-1.1 Ga. This suggests an early colonization of land in the Proterozoic, with implications for weathering, climate, and co-evolution with animals. Heckman, Geiser, Thompson, and Eidell are involved in this work; a manuscript is being prepared. The relationships and timing of metazoan evolution are being studied by Lyons-Weiler, Poling, and Shoe; they plan to finish an initial study of diverse phyla by mid-summer. Van Tuinen and Pfaff are comparing phylogeny and timing of vertebrates that diverged in the Paleozoic and Mesozoic with plate tectonics and impact events; one study was published and another is being completed. Thanks to hard work of the research personnel, most supported by non-NAI funds, we have accomplished more on these projects than initially projected.