title: Modern Quaternary plant lineages promote diversity through facilitation of ancient Tertiary lineages.
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.
authors.affiliation: 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. avali@servidor.unam.mx
authors.forename: Alfonso
authors.initials: A
authors.lastname: Valiente-Banuet
authors.forename: Adolfo Vital
authors.initials: AV
authors.lastname: Rumebe
authors.forename: Miguel
authors.initials: M
authors.lastname: Verdú
authors.forename: Ragan M
authors.initials: RM
authors.lastname: Callaway
mesh_terms: D044822:Biodiversity; D005075:Biological Evolution; D002980:Climate; D003889:Desert Climate; D017753:Ecosystem; D005580:Fossils; D019083:Mediterranean Region; D008800:Mexico; D008954:Models, Biological; D010802:Phylogeny; D010944:Plants / Q000145:classification* / Q000235:genetics*