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2005 Annual Science Report

Pennsylvania State University Reporting  |  JUL 2004 – JUN 2005

Genomic Record of the Earth's Early Biosphere

4 Institutions
3 Teams
0 Publications
0 Field Sites
Field Sites

Project Progress

Our research involves molecular clocks and phylogenetics to better understand the relationship between planetary history and the evolution of life. We made progress in theoretical and empirical studies during the past year. In the former area we developed a method for phylogenetic analysis of complete genome sequences, for use with either prokaryotes or eukaryotes (Blair, Shah, & Hedges, 2005; BMC Bioinformatics 4:53). The method makes use of a conservative criterion (single copy genes) for determining gene orthology, which is a major issue in the field (evolutionary genomics). The procedure is fully automated, which greatly increases the speed at which complete genomes can be analyzed, while still making use of a large number (>1000 in some cases) of genes. In another paper, we presented an analysis of complete prokaryote genomes and better constraints on the origin of organisms producing metabolic products that influenced the history of the biosphere (Battistuzzi & Hedges, 2004; BMC Evol. Biol. 4:44). We found that some divergences occurred before 4 billion years ago, indicating an early origin of life on Earth. We also found an early origin of methanogenesis and phototrophy, but a “late” origin (<3Ga) of oxygenic photosynthesis. In another study (Blair & Hedges, 2005; Mol. Biol. Evol. 22:387-390) we critiqued two recent molecular clock studies by other laboratories bearing on the Cambrian Explosion of animal phyla and concluded that methodological problems in their analyses resulted in biased time estimates. A fourth paper reporting divergence times and phylogeny of deuterostomes (Blair & Hedges, 2005; Mol. Biol. Evol.) has been accepted and is in press.

    S. Blair Hedges
    Project Investigator
    Fabia Battistuzzi
    Doctoral Student

    Jaime Blair
    Doctoral Student

    Objective 4.1
    Earth's early biosphere

    Objective 4.2
    Foundations of complex life