Abstract Detail

Systematics Section/ASPT

Godfrey, Samantha [1], Gillespie, Lynn [2].

Systematics and Phylogeography of Parrya (Brassicaceae) in the North American Arctic.

Parrya (Brassicaceae) includes three species in the North American Arctic that can be difficult to distinguish. Parry nudicaulis is morphologically variable and widespread across Beringia, while P. arctica is widespread in western and central Arctic Canada; their ranges are considered to overlap on southeastern Victoria Island and adjacent mainland Nunavut. Parrya nauraq is a recently described, highly restricted endemic of the Seward Peninsula of Alaska. The objectives of this study were to investigate their relationships and phylogeography, and to better circumscribe P. arctica and P. nudicaulis. Analyses were performed on 26 morphological characters and on DNA sequences of three non-coding regions, nrITS and plastid trnS-trnG and psbJ-petA. Most morphological characters overlapped among species, but the majority of quantitative characters were significantly different and the principal component analysis revealed two well defined clusters corresponding to P. arctica and P. nudicaulis. The plastid strict consensus parsimony tree showed P. arctica to be a genetically uniform monophyletic lineage embedded within a genetically diverse P. nudicaulis, but the ITS tree incompletely resolved the two species, with four P. nudicaulis samples within a P. arctica clade, possibly suggesting past hybridization. The two P. nauruaq specimens examined resolved together within the P. nudicaulis clade in both ITS and plastid trees, but were morphologically closer to P. arctica. Parry nudicaulis has at least five main cpDNA haplotypes, some geographically distinct, others with wide-ranging, broadly overlapping distributions. Two common haplotypes were widespread across much of Alaska and Yukon but absent from interior central parts; a third was restricted to interior Yukon and westernmost Northwest Territories. A less common haplotype was restricted to western central Alaska. The least common haplotype, which is the one most similar to that of P. arctica, was detected only in east interior Alaska and southwestern Northwest Territories. These haplotypes do not correspond to any of the three subspecies of P. nudicaulis based on existing keys. These results indicate that P. nudicaulis and P. arctica should be recognized as distinct, allopatric species, and that all samples on Victoria Island belong to P. arctica. Both P. arctica and P. nauruaq likely evolved from P. nudicaulis, with P. arctica colonizing the Canadian Arctic from Beringia after the last glaciation and P. nauruaq evolving more recently. We discuss the phylogeographic history of Parrya in the North American Arctic in the context of other arctic genera.

1 - University of Ottawa, Biology Department, Ottawa, Ontario, Canada
2 - Canadian Museum of Nature, Research & Collections, PO Box 3443, Station D, Ottawa, ON, K1P 6P4, Canada

Keywords:
Parrya
Brassicaceae
Arctic
Phylogeography
taxonomy.

Presentation Type: Oral Paper:Papers for Sections
Session: 19
Location: Salon 9/The Shaw Conference Centre
Date: Monday, July 27th, 2015
Time: 2:30 PM
Number: 19005
Abstract ID:1318
Candidate for Awards:None