Abstract Detail

Biogeography

Mathews, Katherine Gould [1], Lanning, Max [2].

Stranded or Not: Which Southern Appalachian Rock Outcrop Endemic Plants are Alpine Relicts?

The flora of Southern Appalachian (latitude 35º-37º) high-elevation rock outcrops has numerous rare species and is one of the most distinctive of any habitat in the mountains. These isolated communities are believed to contain relicts of an alpine flora that was widespread in the Southern Appalachians during the last ice age, until 12,000 years ago. Wiser (1994) lists 21 present-day Southern Appalachian endemic species whose recent ancestors may have been part of an alpine flora during the Pleistocene. Twenty-six more rock outcrop species are also found in alpine areas elsewhere or more broadly in the north, giving credence to the alpine relict hypothesis. We wanted to test the hypothesis of alpine ancestry in Southern Appalachian endemic species by reconstructing the phylogenetic history for one group and examining phylogenetic trees already reconstructed for as many endemics as possible. Our phylogenetic reconstruction of the genus Micranthes (formerly Saxifraga) based on the chloroplast gene regions matK, trnL and nrITS sequences and including all species found in the Southern Appalachians, shows that the endemic M. petiolaris (=S. michauxii; Michaux’s saxifrage) is sister to a clade of northwestern U.S. and circumpolar species rather than to other southeastern species. This provides evidence for the alpine relict hypothesis for M. petiolaris. A literature survey, on the other hand, reveals uncertainty. Fourteen of the 21 Southern Appalachian endemic species listed by Wiser could not be found in a phylogenetic study thus far. Of those whose phylogenetic history is known, various biogeographic patterns may be interpreted. For example, Rhododendron vaseyi appears to be part of the older intercontinental eastern U.S.-western U.S.-eastern Asia temperate floristic disjunction, while Carex biltmoreana belongs to a clade containing both circumboreal species and broadly distributed North American species and could have had a Pleistocene origin. Further research is warranted, including estimates of divergence times in taxa with known phylogenetic histories, to determine which rock outcrop species are stranded relicts of a Pleistocene alpine flora.

Broader Impacts:

1 - Western Carolina University, Department of Biology, 132 Natural Science Building, Cullowhee, North Carolina, 28723, USA
2 - Western Carolina University, Department of Biology, 132 Natural Science Building, Cullowhee, NC, 28723, USA

Keywords:
rock outcrop
Appalachian Mountains
Pleistocene
glacial relict
Micranthes.

Presentation Type: Poster:Posters for Topics
Session: P
Location: Hall A/Convention Center
Date: Monday, August 2nd, 2010
Time: 5:30 PM
Number: PBG005
Abstract ID:344