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

WILF, PETER; ESCAPA, IGNACIO

NEW PHYTOLOGIST

WILEY-BLACKWELL PUBLISHING, INC

Lugar: Londres; Año: 2015 vol. 207 p. 283 - 290

0028-646X

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