Genomic Clocks and Animal Evolution

S. Blair Hedges
Department of Biology
208 Mueller Lab
Pennsylvania State University
University Park, PA, USA
telephone: 814-865-9991
fax: 814-865-9131
prestype: Platform
presenter: S. Blair Hedges

Hedges, S. Blair
Department of Biology, Institute of Molecular Evolutionary Genetics, and Astrobiology Research Center, Pennsylvania State University, University Park, PA, USA

Four billion years of mutational change in the genomes of organisms has left a trail of evidence for the evolutionary detectives. A major goal is to reconstruct the branching order and times of divergence of populations, species, and genes. Until recently this goal has been difficult to achieve for many reasons, but primarily for lack of sufficient data. The genome projects are solving the data problem but analytical aspects have become more complex. Available computational tools are useful for grouping similar sequences, but true gene (orthology group) identification involves evolutionary considerations that have yet to be fully automated. New methods are needed for constructing trees and estimating divergence times from hundreds or thousands of genes. Evolutionary genomic studies have shown promise in yielding robust phylogenies and precise time estimates. The results of such studies have revealed that animals diverged from fungi and plants about 1.6 billion years ago, and many animal phyla arose before the Cambrian explosion. Recent evidence bearing on the phylogeny of vertebrates and their timescale of evolution will be discussed.

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