Modern Quaternary plant lineages promote diversity through facilitation of ancient Tertiary lineages
- *Departamento de Ecología de la Biodiversidad, Instituto de Ecología, Universidad Nacional Autónoma de México, A.P. 70-275, C.P. 04510 México D.F., México;
- ‡Centro de Investigaciones sobre Desertificación, Consejo Superior de Investigaciones Científicas, Universitat de València, Generalitat Valenciana, Cami de la Marjal s/n Apartado Oficial, Albal, 46470 Valencia, Spain; and
- §Division of Biological Sciences, University of Montana, Missoula, MT 59812
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Edited by Gordon H. Orians, University of Washington, Seattle, WA, and approved September 25, 2006 (received for review June 14, 2006)
Abstract
One of the most important floristic sorting periods to affect modern plant communities occurred during the shift from the wet Tertiary period to the unusually dry Quaternary, when most global deserts developed. During this time, a wave of new plant species emerged, presumably in response to the new climate. Interestingly, most Tertiary species that have been tracked through the fossil record did not disappear but remained relatively abundant despite the development of a much more unfavorable climate for species adapted to moist conditions. Here we find, by integrating paleobotanical, ecological, and phylogenetic analyses, that a large number of ancient Tertiary species in Mediterranean-climate ecosystems appear to have been preserved by the facilitative or “nurse” effects of modern Quaternary species. Our results indicate that these interdependent relationships among plants have played a central role in the preservation of the global biodiversity and provided a mechanism for stabilizing selection and the conservation of ecological traits over evolutionary time scales.
Footnotes
- †To whom correspondence should be addressed. E-mail: avali{at}servidor.unam.mx
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Author contributions: A.V.-B. and A.V.R. designed research; A.V.-B., A.V.R., M.V., and R.M.C. performed research; A.V.-B., A.V.R., M.V., and R.M.C. contributed new reagents/analytic tools; A.V.-B., A.V.R., M.V., and R.M.C. analyzed data; and A.V.-B., A.V.R., M.V., and R.M.C. wrote the paper.
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The authors declare no conflict of interest.
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This article is a PNAS direct submission.
- Abbreviations:
- Myr,
- million years;
- OU,
- Ornstein–Uhlenbeck
- © 2006 by The National Academy of Sciences of the USA
