Abstract Detail

Systematics Section/ASPT

Allen, Geraldine A [1], Sharpe, Ciara E [1].

Geographic variation and hybridization in a Pacific Northwest lineage of fawn-lilies (Erythronium).

The genus Erythronium includes three distinct clades, of which the western North American lineage (with 17 species) is the most diverse. This group extends from southern British Columbia to the Sierra Nevada of California and includes both widespread and rare endemic species. The species occur in a variety of habitats from lowland forest margins to subalpine meadows. Individual species generally are separated geographically or by elevation, with little or no range overlap. Nevertheless, morphologically intermediate individuals (putative hybrids) have been reported for at least nine of the 17 species. We used DNA sequence data from both nuclear genome (ribosomal ITS) and plastid genome (three noncoding regions) to investigate (i) patterns of genetic variation in the morphologically variable species E. oregonum (Oregon fawn-lily) and related taxa, and (ii) the role of hybridization in shaping morphological and genetic patterns within and among species. Erythronium in western North America comprises two southern and two northern clades, one of which is the Pacific Northwest lineage consisting of E. oregonum and its sister species E. revolutum. These two species are morphologically and ecologically distinct and largely allopatric, coming into contact only at the northern range limit of E. oregonum (Vancouver Island) where they form hybrids in a few localities and show evidence of introgression (plastid capture). More strikingly, E. oregonum populations in southern Oregon show molecular evidence of hybridization with a southern Erythronium lineage. These populations form a distinct ITS lineage that is sister to the remaining E. oregonum populations, and their plastid DNA haplotype is identical with that of the southern Oregon endemic E. hendersonii. These findings confirm that western North American fawn-lilies lack strong reproductive barriers, and indicate that hybrids can form not only between sister taxa but also between more distantly related species. Hybridization has been an important evolutionary force in this group, leading to formation of hybrid swarms, introgression, and occasional hybrid speciation.

1 - University Of Victoria, Department Of Biology, PO BOX 3020 STN CSC, VICTORIA, BC, V8W 3N5, Canada

Keywords:
introgression
hybridization 
plastid capture
ITS
Erythronium.

Presentation Type: Oral Paper:Papers for Sections
Session: 44
Location: Firs North/Boise Centre
Date: Wednesday, July 30th, 2014
Time: 4:30 PM
Number: 44011
Abstract ID:831
Candidate for Awards:None