Genetic consequences of glacial survival and postglacial colonization in Norway spruce: combined analysis of mitochondrial DNA and fossil pollen

Abstract

Norway spruce (Picea abies [L.] Karst.) is a broadly distributed European conifer tree whose history has been intensively studied by means of fossil records to infer the location of full-glacial refugia and the main routes of postglacial colonization. Here we use recently compiled fossil pollen data as a template to examine how past demographic events have influenced the species' modern genetic diversity. Variation was assessed in the mitochondrial nad1 gene containing two minisatellite regions. Among the 369 populations (4876 trees) assayed, 28 mitochondrial variants were identified. The patterns of population subdivision superimposed on interpolated fossil pollen distributions indicate that survival in separate refugia and postglacial colonization has led to significant structuring of genetic variation in the southern range of the species. The populations in the northern range, on the other hand, showed a shallow genetic structure consistent with the fossil pollen data, suggesting that the vast northern range was colonized from a single refugium. Although the genetic diversity decreased away from the putative refugia, there were large differences between different colonization routes. In the Alps, the diversity decreased over short distances, probably as a result of population bottlenecks caused by the presence of competing tree species. In northern Europe, the diversity was maintained across large areas, corroborating fossil pollen data in suggesting that colonization took place at high population densities. The genetic diversity increased north of the Carpathians, probably as a result of admixture of expanding populations from two separate refugia.

Distribution patterns of European lacustrine gastropods: a result of environmental factors and deglaciation history

“…Thus, species composition in LG1 is random but spatially autocorrelated due to dispersal limitation of species (see Tuomisto & Ruokolainen, 2006 and references therein). Although lakes in LG1 are characterized by widespread species, differences in the mode of dispersal, e.g., active versus passive (see Kappes & Haase, 2012), in combination with different post-glacial recolonization routes (e.g., Refseth et al, 1998;Tollefsrud et al, 2008), time from deglaciation (see Andrén et al, 2011) and the presence of geographical barriers may explain our findings. The partial Mantel tests showed that environmental distances are more important than geographical distances in LG2.…”

Glacial refugia and post-glacial colonization patterns in European bryophytes

“…Most of Russia, except the westernmost parts and north-western coast, remained icefree during the LGM (Svendsen et al 2004). Molecular studies support the hypothesis of glacial refugia east of the ice for several vascular plants (Ehrich et al 2008, Tollefs-(Ehrich et al 2008, Tollefsrud et al 2008, implying that the area also was suitable for a range of bryophytes during the LGM.…”

New insights on the speciation history and nucleotide diversity of three boreal spruce species and a Tertiary relict

“…Second, IM models further assume a two-species system, where there is no gene flow with any other species. This is clearly not the case in this study, where at least the four included species seem to have exchanged genes with each other and with species not considered here: gene flow between P. glauca and P. engelmanii, and between P. mariana and P. rubens has been documented (for example, Perron and Bousquet, 1997;Major et al, 2005), and P. abies and P. obovata have a large hybrid zone centred around the Ob river (Tollefsrud et al, 2008). However, because P. engelmanii can be considered as a subspecies of P. glauca (Rajora and Dancik, 2000) and P. rubens a derivative of P. mariana (Perron et al, 2000), putative gene flow between them and the species studied here might have a minor effect on the level of polymorphism of the latter.…”