Abstract Detail

Systematics Section/ASPT

Wefferling, Keir [1], Hoot, Sara [2].

Disentangling the Subalpine Marshmarigold Species Complex: Hybridization and Speciation in Caltha leptosepala (Ranunculaceae).

This first phylogenetic and biogeographic study of the Caltha leptosepala species complex examines spatial genetic patterns across a broad range of latitudes in western North America in order to shed light on the evolutionary history of a high altitude plant. Subalpine marshmarigold grows in wet montane to subalpine regions of western North America from New Mexico, Arizona, and California in the south to Alaska and the Yukon in the north, often emerging through snow or ice early in the high-altitude spring. The species complex forms an ideal study system for inferring historical events as the plants are extremely cold tolerant (suggesting an ability to persist in small and northern refugia), lack specialized dispersal mechanisms (enhancing spatial genetic structure), and display morphological divergence and diversity across their range (allowing independent interpretations of biogeographic history). C. leptosepala s.l. (syn. C. howellii and C. biflora) has been variously classified as comprising two species (with subdivision), two subspecies (of C. leptosepala), up to nine species, or as a single taxon with no subdivision due to continuous morphological variation. Taxonomy of the group still varies depending on the source, and hybrids are suspected in northern parts of the range, potentially complicating phylogenetic inference. Sampling from across the extant range of the species complex and using morphological characters, highly variable chloroplast spacer regions (cpDNA; rpl32-trnL^(UAG) and trnL-trnF) and internal transcribed spacer regions of nuclear ribosomal DNA (ITS), we have begun to disentangle evolutionary relationships within C. leptosepala s.l. Preliminary maximum parsimony analysis and Bayesian inference (for ~60 specimens) strongly support the monophyly of C. leptosepala with clear subdivision between an interior, Rocky Mountains clade (C. leptosepala ssp. leptosepala) and a submaritime, Sierra Nevada/Cascade/coastal British Columbia clade (C. leptosepala ssp. howellii). The presence of hybrids (from the Pacific Northwest north to the Alaskan Peninsula) formed between interior and coastal lineages is evidenced by multiple, divergent cloned ITS ribotypes and by unique, intermediate morphology. These putative hybrids all share cpDNA haplotypes of the western submaritime lineage, suggesting chloroplast capture in their history. Concordance between species divergence, introgression, and glacial history of the region will be discussed.

1 - University Of Wisconsin, Lapham Hall S394, PO Box 413, Milwaukee, WI, 53201, USA
2 - University Of Wisconsin, DEPT OF BIOL SCI/LAPHAM HALL, PO BOX 413, MILWAUKEE, WI, 53201, USA

Keywords:
Caltha
Ranunculaceae
Phylogeny
hybrid origin
montane
ITS.

Presentation Type: Oral Paper:Papers for Sections
Session: 17
Location: Payette/Boise Centre
Date: Tuesday, July 29th, 2014
Time: 10:45 AM
Number: 17011
Abstract ID:506
Candidate for Awards:George R. Cooley Award