A Systematic Analysis of the Alpine Saxifrage Complex (Saxifragaceae) in the Canadian Arctic Islands Using Morphology and Chloroplast DNA Data

Abstract

The Saxifraga nivalis complex displays significant ecological, morphological and cytological variation. Most European studies suggest that the S. nivalis complex comprises two distinct species: Saxifraga nivalis sensu stricto and Saxifraga tenuis. However, the presence of intermediate morphotypes, inconsistencies in chromosomal counts and variability in morphological keys and descriptions have led to different taxonomic interpretations of the complex in North America. This study investigated the systematics of Canadian Arctic Island members of this complex from 157 specimens using 23 morphological characters. Principal component analysis of the morphological data revealed two adjacent clusters, corresponding to the two taxa and consistent with a close morphological similarity and the presence of hybrids. A preliminary restriction site analysis of five non-coding regions of the chloroplast genome, trnH-trnK, trnT-trnF, trnF-trnV, trnV-rbcL and rbcL-ORF106, was conducted using 21 restriction endonucleases. This analysis indicated a length difference between the trnT-trnF region of S. nivalis and that of S. tenuis, but no difference in restriction sites for any of the assayed regions. These results confirm that in the Canadian Arctic, the S. nivalis complex consists of two closely related, largely sympatric species, with notable morphological variability, and possible hybrids.