Evolution

Mapping Life's History

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Science  12 Jun 2009:
Vol. 324, Issue 5933, pp. 1366
DOI: 10.1126/science.324_1366a
CREDIT: ULF MOLAU, UNIVERSITY OF GOTHEMBURG, SWEDEN

The tropical region of the New World hosts the richest plant diversity in the world, a richness that owes much to the complex tectonic history of this part of the Earth. Focusing on two tribes of the family Rubiaceae (which includes the coffee plant among many others), Antonelli et al. have traced how the uplift of the Andes has influenced the spatial and temporal evolution of neotropical plant diversity—not only in the mountains but also in the lowlands. Molecular phylogeographic analysis shows how the initial uplift of the western and central Andes beginning in the Eocene inhibited dispersal and led to diversification in the lowlands, while creating new montane habitats and taxa. Further barriers to dispersal between Amazonia and the mountains were imposed by marine incursions and the formation during the Miocene of the huge, but now-vanished, wetland (referred to as Lake Pebas or the Pebas Sea) to the east of the Andes. The disappearance of Lake Pebas and the establishment of the modern Amazon drainage are reflected in the distribution and speciation of younger lowland taxa in western Amazonia. The Miocene uplift of the eastern Cordillera of the Andes (shown above) meanwhile promoted dispersal of montane taxa.

Proc. Natl. Acad. Sci. U.S.A. 106, 10.1073/pnas.0811421106 (2009).

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