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A Survey Of Nuclear Ribosomal Internal Transcribed Spacer Substitution Rates Across Angiosperms: An Approximate Molecular Clock With Life History Effects, Kathleen M. Kay, Justen B. Whittall, Scott A. Hodges

Biology

Background: A full understanding of the patterns and processes of biological diversification requires the dating of evolutionary events, yet the fossil record is inadequate for most lineages under study. Alternatively, a molecular clock approach, in which DNA or amino acid substitution rates are calibrated with fossils or geological/climatic events, can provide indirect estimates of clade ages and diversification rates. The utility of this approach depends on the rate constancy of molecular evolution at a genetic locus across time and across lineages. Although the nuclear ribosomal internal transcribed spacer region ( nrITS) is increasingly being used to infer clade ages in …