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Glacial survival does not matter: RAPD phylogeography of Nordic Saxifraga oppositifolia
Author(s) -
GABRIELSEN T. M.,
BACHMANN K.,
JAKOBSEN K. S.,
BROCHMANN C.
Publication year - 1997
Publication title -
molecular ecology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.619
H-Index - 225
eISSN - 1365-294X
pISSN - 0962-1083
DOI - 10.1046/j.1365-294x.1997.d01-215.x
Subject(s) - biology , rapd , analysis of molecular variance , phylogeography , arctic , genetic variation , glacial period , ecology , beringia , mantel test , gene flow , population , genetic diversity , phylogenetic tree , biochemistry , paleontology , demography , sociology , gene
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 glacial survival hypothesis is superfluous.