Fossils vs. molecular record (Introduction)

by David Turell @, Friday, June 20, 2014, 16:07 (3597 days ago)

The study of the genetic record doesn't fit the fossil tree of life:-http://rspb.royalsocietypublishing.org/content/281/1788/20140677.abstract-From the paper:-"Our results suggest that, for Aves, discord between molecular divergence estimates and the fossil record is pervasive across clades and of consistently higher magnitude for younger clades. [...] Unexpectedly, relative disparity is substantially higher for crown than for stem divergences. This observation is difficult to attribute to fossil preservation biases. The quality of the fossil record is expected to improve from the past towards the present, because more fossil bearing rocks are preserved from younger deposits. If disparity were primarily driven by gaps in the fossil record, one would expect the gap between the divergence of a lineage and its oldest known fossil to be smaller on average for the basal crown divergence in each clade, which by definition occurred more recently than the stem divergence. [...] In sum, biases in the fossil record predict larger gaps between genetic divergences and fossil occurrences for stem divergences than for crown divergences, yet the opposite pattern is observed. [...] Though often mischaracterized as scrappy, the fossil record of modern birds is now sampled from hundreds of thousands of specimens from throughout the Cenozoic. As increasing efforts have yielded vast numbers of new specimens but failed to reconcile the gap between molecular and fossil evidence, it becomes less plausible to attribute disparity solely to gaps in the fossil record."-The message is clear that genetic records will show a more accurate depiction of evolution.

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