Molecular Clocks Do Not Support the Cambrian Explosion

Authors: Blair, Jaime E.; Hedges, S. Blair

Source: Molecular Biology and Evolution, Volume 22, Number 3, March 2005 , pp. 387-390(4)

Publisher: Oxford University Press

Buy & download fulltext article:

OR

Price: $42.29 plus tax (Refund Policy)

Abstract:

The fossil record has long supported the view that most animal phyla originated during a brief period approximately 520 MYA known as the Cambrian explosion. However, molecular data analyses over the past 3 decades have found deeper divergences among animals (sim800 to 1,200 MYA), with and without the assumption of a global molecular clock. Recently, two studies have instead reported time estimates apparently consistent with the fossil record. Here, we demonstrate that methodological problems in these studies cast doubt on the accuracy and interpretations of the results obtained. In the study by Peterson et al., young time estimates were obtained because fossil calibrations were used as maximum limits rather than as minimum limits, and not because invertebrate calibrations were used. In the study by Aris-Brosou and Yang, young time estimates were obtained because of problems with rate models and other methods specific to the study, and not because Bayesian methods were used. This also led to many anomalous findings in their study, including a primate-rodent divergence at 320 MYA. With these results aside, molecular clocks continue to support a long period of animal evolution before the Cambrian explosion of fossils.

Keywords: animals; Metazoa; time estimation; evolution; fossil record

Document Type: Research article

DOI: http://dx.doi.org/10.1093/molbev/msi039

Publication date: 2005-03-01

More about this publication?
  • Molecular Biology and Evolution publishes research at the interface between molecular and evolutionary biology. The journal publishes investigations of molecular evolutionary patterns and processes, tests of evolutionary hypotheses that use molecular data, and studies that use molecular evolutionary information to address questions about biological function at all levels of organization.
Related content

Key

Free Content
Free content
New Content
New content
Open Access Content
Open access content
Subscribed Content
Subscribed content
Free Trial Content
Free trial content

Text size:

A | A | A | A
Share this item with others: These icons link to social bookmarking sites where readers can share and discover new web pages. print icon Print this page