Glacial survival does not matter: RAPD phylogeography of Nordic Saxifraga oppositifolia

• Published in: Molecular Ecology
• Main Authors: GABRIELSEN, T. M., BACHMANN, K., JAKOBSEN, K. S., BROCHMANN, C.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Wiley 1997
• Subjects: Arctic; Norway; Svalbard; Northern Norway; Novaya Zemlya; Saxifraga oppositifolia
• Online Access: http://dx.doi.org/10.1046/j.1365-294x.1997.d01-215.x; https://api.wiley.com/onlinelibrary/tdm/v1/articles/10.1046%2Fj.1365-294X.1997.d01-215.x; https://onlinelibrary.wiley.com/doi/pdf/10.1046/j.1365-294X.1997.d01-215.x

Abstract The arctic‐alpine Saxifraga oppositifolia has recently been suggested to have survived the last glaciation in high‐arctic refugia, based on a finding of more genetic (RFLP) variation in Svalbard compared with more southern areas. To elucidate the migration history of this allogamous species, we analysed 18 populations from Norway, Svalbard and Novaya Zemlya using random amplified polymorphic DNAs (RAPDs). There was no more RAPD variation in the high Arctic than further south. In an analysis of molecular variance (AMOV A), most of the RAPD variation was found within populations (64%). There was less intrapopulational variation in Svalbard (65%) than in northern Norway (78%) and southern Norway (86%), suggesting that there is more inbreeding towards the north, probably because of lower pollinator activity. Twenty‐eight per cent of the RAPD variation was found among populations within these geographical regions, and only 9% was found among the regions. In PCO and UPGMA analyses, plants and populations of different geographical origins were to a large extent intermingled. There was, however, a distinct, south‐north clinal geographical structuring of the RAPD variation both in the PCO analysis and in a spatial autocorrelation (Mantel) analysis. These results suggest that there has been extensive gene flow among more or less continuously distributed populations of S. oppositifolia during the Weichselian, and that the extant Nordic populations were established after massive, centripetal immigration from these genetically variable, periglacial populations. The postglacial period may not have been sufficiently long for the subsequently isolated populations of this long‐lived, allogamous perennial to diverge. Given the high levels of migration inferred from this study, genetic differentiation of glacial survivor populations, if any existed, would most likely have been swamped in the postglacial period. Thus, our molecular data support recent conclusions based on palaeobotanical and biogeographical data that the ...