Abstract Detail

Biogeography

Rebernig, Carolin A. [2], Schneeweiss, Gerald M. [1], Bardy, Katharina E. [2], Schoenswetter, Peter [1], Villasenor, Jose L. [3], Obermayer, Renate [2], Stuessy, Tod F. [2], Schneeweiss, Hanna [2].

Multiple Pleistocene refugia and Holocene range expansion of an abundant southwestern American desert plant species (Melampodium leucanthum, Asteraceae).

Pleistocene climatic fluctuations had major impacts on desert biota in southwestern North America. During cooler and wetter periods, drought-adapted species were isolated into refugia, in contrast to expansion of their ranges during massive aridification in the Holocene. Here we use Melampodium leucanthum (Asteraceae), a species of the North American desert and semi-desert regions, to investigate the impact of the major aridification in southwestern North America on phylogeography and evolution in a widespread and abundant drought-adapted plant species. The evidence for three separate Pleistocene refugia at different time levels suggests that this species responded to the Quaternary climatic oscillations in a cyclic manner. In the Holocene, once differentiated lineages came into secondary contact and intermixed, but these range expansions did not follow the eastwardly progressing aridification, but occurred independently out of separate Pleistocene refugia. As in other desert biota, the Continental Divide acted as a major migration barrier for M. leucanthum since the Pleistocene. Despite being geographically restricted to the eastern part of the species’ distribution, autotetraploids in M. leucanthum originated multiple times and do not form a genetically cohesive group.

Broader Impacts:

1 - University of Vienna, Department of Biogeography, Rennweg 14, Vienna, A-1030, Austria
2 - University of Vienna, Department of Systematic and Evolutionary Botany, Rennweg 14, Vienna, A-1030, Austria
3 - Universidad Nacional Autónoma de México, Instituto de Biología, Departamento de Botánica, Tercer Circuito s/n, Ciudad Universitaria, Delegación Coyoacán, México D. F., MX-04510 , Mexico

Keywords:
desert biota
Holocene aridification
Melampodium
phylogeography
polyploidy
refugia.

Presentation Type: Oral Paper:Papers for Topics
Session: 28
Location: 552B/Convention Center
Date: Tuesday, August 3rd, 2010
Time: 8:30 AM
Number: 28003
Abstract ID:297