Abstract Detail

Systematics Section/ASPT

Folk, Ryan [1], Freudenstein, John [1].

“Sky islands” in the eastern US? – Strong phylogeographic structure in the Heuchera parviflora group (Saxifragaceae).

Heuchera parviflora is a rare saxicolous plant that occurs widely in dissected plateau regions in the unglaciated Eastern US. In the context of several taxonomic segregates, variable morphology, and initial observations of molecular divergence, we conducted a molecular analysis that included recently developed algorithms for “species delimitation.” Concatenated ML analysis resulted in a tree with several well-supported clades that were morphologically and geographically consistent: (1) an Ozarks clade, (2) an Interior Plateau + southern Cumberland clade, (3) a northern Cumberland clade, and (4) a Piedmont clade. We used these clades as an initial hypothesis of species limits to test in BPP and SpedeSTEM, two molecular species delimitation approaches. Both analyses strongly supported a four-species model as opposed models with fewer species. BPP requires that the user set several parameter assumptions that have been shown to affect analyses, but given the small number of taxa we were able to test various combinations of all parameters with no effect on the results. We conclude that Heuchera parviflora as currently conceived contains four distinctive allopatric genetic lineages. Morphologically they are easy to distinguish in the field but it is difficult to work with pressed material. Since rare intermediates exist for some characters (such as petiole indumentum) we consider that the best taxonomic rank for these lineages may be variety rather than species, in contrast to most analyses that use these techniques. Three of these lineages already have taxonomic names associated with them, one of which must be considerably widened in taxonomic concept. The Piedmont lineage, however, has never been described as distinct and will require a new name.

1 - Ohio State University, MUSEUM OF BIOLOGICAL DIVERSITY, 1315 KINNEAR RD, COLUMBUS, OH, 43212-1157, USA

Keywords:
Heuchera
species delimitation
lineage
phylogeography
taxonomy.

Presentation Type: Oral Paper:Papers for Sections
Session: 17
Location: Payette/Boise Centre
Date: Tuesday, July 29th, 2014
Time: 8:30 AM
Number: 17003
Abstract ID:223
Candidate for Awards:George R. Cooley Award