Recente montagem do Cerrado, um centro complicado de diversidade de planta neotropical, por evolução in situ de adaptações ao fogo

Recent assembly of the Cerrado, a neotropical plant diversity hotspot, by in situ evolution of adaptations to fire

Marcelo F. Simon a,b,1, Rosaura Grether c, Luciano P. de Queiroz d, Cynthia Skema e,2, R. Toby Pennington e and Colin E. Hughes a
- Author Affiliations

aDepartment of Plant Sciences, University of Oxford, South Parks Rd, Oxford, OX1 3RB, United Kingdom;

bEmbrapa Recursos Genéticos e Biotecnologia, PqEB, Caixa Postal 02372, 70770–917, Brasília-DF, Brazil

cDepartamento de Biología, Universidad Autónoma Metropolitana-Iztapalapa, Apdo. Postal 55–535, 09340 México, D.F. México;

dDepartamento de Ciências Biológicas, Universidade Estadual de Feira de Santana, Km 03, BR 116, Campus, 44031–460, Feira de Santana-BA, Brazil; and

eRoyal Botanic Garden Edinburgh, 20a Inverleith Row, Edinburgh, EH3 5LR, United Kingdom

↵2Present address: L. H. Bailey Hortorium, Cornell University, 412 Mann Library, Ithaca, NY 14853.

Edited by Mary Arroyo, University of Chile, Santiago, Chile, and approved October 12, 2009 (received for review March 27, 2009)

Abstract

The relative importance of local ecological and larger-scale historical processes in causing differences in species richness across the globe remains keenly debated. To gain insight into these questions, we investigated the assembly of plant diversity in the Cerrado in South America, the world's most species-rich tropical savanna. Time-calibrated phylogenies suggest that Cerrado lineages started to diversify less than 10 Mya, with most lineages diversifying at 4 Mya or less, coinciding with the rise to dominance of flammable C4 grasses and expansion of the savanna biome worldwide. These plant phylogenies show that Cerrado lineages are strongly associated with adaptations to fire and have sister groups in largely fire-free nearby wet forest, seasonally dry forest, subtropical grassland, or wetland vegetation. These findings imply that the Cerrado formed in situ via recent and frequent adaptive shifts to resist fire, rather than via dispersal of lineages already adapted to fire. The location of the Cerrado surrounded by a diverse array of species-rich biomes, and the apparently modest adaptive barrier posed by fire, are likely to have contributed to its striking species richness. These findings add to growing evidence that the origins and historical assembly of species-rich biomes have been idiosyncratic, driven in large part by unique features of regional- and continental-scale geohistory and that different historical processes can lead to similar levels of modern species richness.

Footnotes

1To whom correspondence should be addressed. E-mail: msimon@cenargen.embrapa.br

Author contributions: M.F.S. and C.E.H. designed research; M.F.S., R.G., L.P.d.Q., C.S., R.T.P., and C.E.H. performed research; M.F.S., C.S., and C.E.H. analyzed data; and M.F.S., R.G., L.P.d.Q., C.S., R.T.P., and C.E.H. wrote the paper.

The authors declare no conflict of interest.

This article is a PNAS Direct Submission.

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