Annual plants colonizing the Arctic? Phylogeography and genetic variation in the Euphrasia minima complex (Orobanchaceae)
The high-arctic environment supports very few annual plants, but more annuals can be expected to move northwards following climate warming. Here we address the history of the amphi-Atlantic, hemiparasitic Euphrasia minima complex, which is taxonomically intricate and consists
of annuals typically growing in alpine, north boreal, and low-arctic habitats. Recently it has also been discovered at three distantly separated sites in the high-arctic archipelago of Svalbard. We analyzed Amplified Fragment Length Polymorphism (AFLP) and chloroplast DNA (cpDNA) variation
in populations from most of the range of the complex. The main split observed in both datasets, dated to nearly 6 Ma ago, was between one central/southern European alpine lineage (E. minima s.str.) and one northern amphi-Atlantic lineage (E. wettsteinii). The E. wettsteinii
lineage consisted of two cpDNA sublineages, both amphi-Atlantic and partly sympatric, estimated to have diverged 1.7 Ma ago. Two main northern subgroups were also revealed in the AFLP dataset, partly consistent with the cpDNA sublineages: one E Atlantic subgroup (N Russia, extending into Scotland
and Colesdalen in Svalbard), and one mainly W Atlantic subgroup (NE Canada, Greenland, and Iceland, extending into N Norway). A third subgroup was restricted to two of the three Svalbard populations, Bockfjorden and Ossian Sarsfjellet. Assignment tests of the Svalbard populations suggest that
Colesdalen was derived from N Russian source populations and Bockfjorden from N Norwegian ones; the assignment of the Ossian Sarsfjellet population was uncertain. However, as all Svalbard populations were distinctly divergent from each other as well as from all other populations in AFLP marker
frequencies, it is unlikely that their establishment in Svalbard is caused by the current climate warming or recent human activities. Their divergence is probably due to founder effects and genetic drift following independent earlier immigrations, possibly during the postglacial warm period
9500 to 4000 years ago.
AMPLIFIED FRAGMENT LENGTH POLYMORPHISM (AFLP);
Document Type: Research Article
National Centre for Biosystematics, Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, 0318 Oslo, Norway, Department of Botany, St. Petersburg State University, St. Petersburg, Russia; no, Email: firstname.lastname@example.org
Tromsø University Museum, University of Tromsø, 9037, Tromsø, Norway, The University Centre in Svalbard, P.O. Box 156, 9171 Longyearbyen
National Centre for Biosystematics, Natural History Museum, University of Oslo, P.O. Box 1172 Blindern, 0318 Oslo, Norway
Publication date: February 21, 2012
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