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Abstract Detail

Systematics Section/ASPT

Nazaire, Mare [1], Hufford, Larry [2].

Geographic origins and patterns of radiation in Mertensia (Boraginaceae).

We investigated the geographic origin and temporal and spatial diversification of Mertensia (Boraginaceae), giving particular attention to the divergence between Asian and North American lineages and the radiation of clades in western North America. Phylogeny reconstruction used DNA sequence data from the nrITS region and 12 cpDNA regions and a broad sampling of the asterid clade to estimate divergence times in Boraginaceae and to infer geographic patterns in Mertensia. The dating analysis indicates that the stem lineage of Mertensia split from its extant sister, Asperugo, in the late Oligocene to mid Miocene (26.83–12.22 million years ago (Ma)), followed by the first divergence in the crown group in the late Miocene (10.36–5.19 Ma). The crown divergence of Mertensia coincides with the onset of extreme cooling and the fragmentation of a once extensive mixed mesophytic forest that was replaced with coniferous forests and boreal elements. From geographic reconstructions, we infer the ancestral area for Mertensia to have been Asia or a widespread distribution across Asia, Beringia, and circumboreal locales, with a small probability of a North American ancestry. From the present trans-Beringian distribution of Mertensia, we infer that Beringia likely played an important role in the early geographic radiation of the genus. Initial range expansion of North American mertensias occurred in Beringia and the Pacific Northwest during the late Miocene to early Pliocene (7.70–4.22 Ma), followed by diversification of three deep clades (Pacific Northwest clade, Southern Rocky Mountain clade, Central Rocky Mountain clade). The Southern Rocky Mountain clade and Central Rocky Mountain clade used the Rocky Mountains for range expansion from the Pacific Northwest with subsequent range expansions into the Great Basin-Columbia Plateau, Appalachian region of eastern North America, and northward to Beringia. Our results indicate that the Rocky Mountain Range played an important role in migration and diversification of North American mertensias. Glacial-interglacial cycles during the Pleistocene appear to have been important in the diversification of the North American clade.

Broader Impacts:

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1 - Washington State University, P.O. Box 644236, Pullman, WA, 99164-4236, USA
2 - Washington State University, SCHOOL OF BIOLOGICAL SCIENCES, 312 Abelson Hall, PULLMAN, WA, 99164-4236, USA

ancestral area reconstruction
divergence time analyses
Species richness.

Presentation Type: Oral Paper:Papers for Sections
Session: 13
Location: Rosedown/Riverside Hilton
Date: Monday, July 29th, 2013
Time: 4:00 PM
Number: 13010
Abstract ID:161
Candidate for Awards:George R. Cooley Award

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