Uma Web Verde ou um relógio molecular mega-enviesado???

domingo, maio 29, 2016

Green Web or megabiased clock? Plant fossils from Gondwanan Patagonia speak on evolutionary radiations

Author for correspondence:

Peter Wilf
Tel: +1 814 865 6721

Received: 31 July 2014 Accepted: 12 September 2014

Peter Wilf1 and Ignacio H. Escapa2

Department of Geosciences, Pennsylvania State University, University Park, PA 16802, USA; 

CONICET, Museo Paleontol ogico

Egidio Feruglio, Avenida Fontana 140, 9100 Trelew, Chubut, Argentina

New Phytologist (2015) 207: 283–290

Key words: divergence dating, evolutionary radiations, geochronology, Gondwana, molecular clocks, paleobotany, Patagonia.


Evolutionary divergence-age estimates derived from molecular ‘clocks’ are frequently correlated with paleogeographic, paleoclimatic and extinction events. One prominent hypothesis based on molecular data states that the dominant pattern of Southern Hemisphere biogeography is post-Gondwanan clade origins and subsequent dispersal across the oceans in a metaphoric ‘Green Web’. We tested this idea against well-dated Patagonian fossils of 19 plant lineages, representing organisms that actually lived on Gondwana. Most of these occurrences are substantially older than their respective, often post-Gondwanan molecular dates. The Green Web interpretation probably results from directional bias in molecular results. Gondwanan history remains fundamental to understanding Southern Hemisphere plant radiations, and we urge significantly greater caution when using molecular dating to interpret the biological impacts of geological events.

FREE PDF GRATIS: New Phytologist


We urge significantly greater caution when using molecular dates in the explicit context of geologic time and Earth history. The fossil record is always incomplete, but its exciting potential is only beginning to develop in many parts of the world. Future improvements in molecular dating seem very likely, but for now, fossils and geochronology provide the only rigorous, enduring temporal framework for evolutionary radiations.