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A phylogeographic approach is the only way to study the dispersal history of most algae, which are rarely preserved as fossils. However, the only freshwater alga for which this approach has been applied on a Eurasian scale is the endangered green alga Aegagropila linnaei, which is thought to be a poor disperser. Previous phylogeographic results were explained by stepwise dispersal across the Holarctic from an ancestral area in Japan, with further survival in European ice-dammed glacial lakes and extinction in continental Siberia, which lacks such refugia. To clarify the biogeography of A. linnaei in Eurasia we supplemented the published data on its ribotype (internal transcribed spacer of ribosomal DNA) distribution with data from previously unexplored East Europe, Mongolia and the Russian Far East. We have found two new ribotypes, one scattered across temperate Europe and another confined to one locality in the north-eastern Russian Far East. We also expanded the distribution of a ribotype previously reported from Scotland and continental West Europe to include East Europe, Iceland and Central Mongolia. Phylogeogeographic approach based on enhanced sampling allowed us to refine the biogeography of A. linnaei. We discuss reasons for underestimation of A. linnaei dispersal potential. A focused inventory of A. linnaei will likely reveal new localities of the species enabling a further improvement in biogeographical reconstructions. Area-wide studies of other freshwater algae in Eurasia need to be performed to test the generality of the revealed biogeographical patterns. [ABSTRACT FROM AUTHOR]

Within the moss genus Timmia, three or four sections have been suggested based on morphology. Earlier studies conflicted in suggesting that T. austriaca Hedw. either displays limited phylogeographical structure or includes large molecular variation with potential for geographical structure. Relationships within Timmia were inferred from variation in the nuclear 26S and plastid atpB–rbcL and trnL–trnF. New sequences were generated for 64 specimens of T. austriaca. For other Timmia species, sequences came primarily from earlier studies or GenBank. Timmia includes two main, well-supported molecular lineages. Within T. austriaca, four arctic or subarctic specimens resolved in a small-lineage sister to all other specimens. Recognition of two sections is suggested: Timmia Hedw. sect. Timmia (syn. sect. Timmiaurea Brassard; syn. sect. Sphaerocarpa Y.Jia & Yang Liu bis) and sect. Norvegica Brassard. Timmia fossils, including T. austriaca, were deposited at least 3 Myr BP in northernmost North America under a milder climate than presently in that area. It is theorised that plants of the small T. austriaca lineage evolved adaptations to survive only under cold conditions, when the Arctic was gradually cooling. Timmia austriaca disperses easily, and because the numerous temperate region samples studied included no representatives of the northern lineage, the restricted distribution of this lineage is suggested to have resulted from adaptation to cold environments. In situ survival of T. austriaca in Fennoscandia during the Late Glacial Maximum, as previously theorised, is deemed unlikely due to glacial erosion and submergence of large areas as a result of isostatic depression. [ABSTRACT FROM AUTHOR]

The extent of glacial survival of woody plants in temperate Asia is still poorly known. A reliable way to clarify this issue in the absence of sufficient paleontological data is a phylogeographic analysis of contemporary populations. A recent study of Juniperus communis genetic diversity in Eurasia suggested that this species with wide ecological tolerance survived the glaciation in many periglacial microrefugia at high latitudes and subsequently spread to new areas during interglacials (Hantemirova et al. in J Biogeogr 44:271–282, 2017. 10.1111/jbi.12867). This pattern was termed a "new Eurasian phylogeographical paradigm" as opposed to survival in few major refugia. We have tested the proposed "paradigm" with another hardy species with wide Eurasian area, Prunus padus, to find out if any general phylogeographic patterns may exist for cold-tolerant Eurasian arboreal plant species. We interpret the observed genetic structure [nuclear (ITS) and plastid DNA] of the Eurasian populations of P. padus as plausibly resulted from at least two cycles of glacial survivals in refugia followed by post-glacial colonization events. The species likely originated in East Asia and subsequently spread across all Eurasia. Its continuous range had been fragmented by early-Pleistocene glaciations, when the species survived in the Caucasian and Far Eastern refugia as well as in northern periglacial microrefugia with an active gene flow between them. The known major glacial refugia, such as Iberian Peninsula, the Colchis, the Southern Urals, and the Beringia, played little role as a source of the species post-glacial expansion. [ABSTRACT FROM AUTHOR]

Quaternary glaciations have played a major role in shaping the genetic diversity and distribution of plant species. Strong palaeoecological and genetic evidence supports a postglacial recolonization of most plant species to northern Europe from southern, eastern and even western glacial refugia. Although highly controversial, the existence of small in situ glacial refugia in northern Europe has recently gained molecular support. We used genomic analyses to examine the phylogeography of a species that is critical in this debate. Carex scirpoidea Michx subsp. scirpoidea is a dioecious, amphi‐Atlantic arctic–alpine sedge that is widely distributed in North America, but absent from most of Eurasia, apart from three extremely disjunct populations in Norway, all well within the limits of the Weichselian ice sheet. Range‐wide population sampling and variation at 5,307 single nucleotide polymorphisms show that the three Norwegian populations comprise unique evolutionary lineages divergent from Greenland with high between‐population divergence. The Norwegian populations have low within‐population genetic diversity consistent with having experienced genetic bottlenecks in glacial refugia, and host private alleles that probably accumulated in long‐term isolated populations. Demographic analyses support a single, pre‐Weichselian colonization into Norway from East Greenland, and subsequent divergence of the three populations in separate refugia. Other refugial areas are identified in North‐east Greenland, Minnesota/Michigan, Colorado and Alaska. Admixed populations in British Columbia and West Greenland indicate postglacial contact. Taken together, evidence from this study strongly indicates in situ glacial survival in Scandinavia. [ABSTRACT FROM AUTHOR]

The Qinghai–Tibet Plateau (QTP) has been considered as one of the most sensitive regions to climate change on Earth, and the growth and distribution of alpine species on this plateau have been suggested to depend greatly on their ability to survive within a small range of temperatures. However, the responses of most species in the QTP to the Quaternary climatic oscillation remain largely unknown. We sequenced two cpDNA fragments and nrITS to examine genetic variations in 22 natural populations across the range of distribution in this region to investigate the phylogeographical distributional pattern of Gentiana straminea (Gentianaceae) in the QTP. The high haplotype diversity from populations on the platform suggested the existence of intraspecific diversification. Molecular dating estimated that all haplotypes have differentiated before the Last Glacial Maximum (LGM). Moreover, the haplotype distribution map based on both cpDNA and nrDNA data suggested expansions from QTP to its outer edges. Finally, ecological niche modeling further demonstrated the glacial survival of this species on the platform and continuous expansion to the platform edge. These findings imply that G . straminea should have experienced initial diversification, glacial survival on the platform, and continuous expansion to the QTP edge during the glacial period. [ABSTRACT FROM AUTHOR]

We test for the congruence between allele-based range boundaries (break zones) in silicicolous alpine plants and species-based break zones in the silicicolous flora of the European Alps. We also ask whether such break zones coincide with areas of large elevational variation. The European Alps. On a regular grid laid across the entire Alps, we determined areas of allele- and species-based break zones using respective clustering algorithms, identifying discontinuities in cluster distributions (breaks), and quantifying integrated break densities (break zones). Discontinuities were identified based on the intra-specific genetic variation of 12 species and on the floristic distribution data from 239 species, respectively. Coincidence between the two types of break zones was tested using Spearman's correlation. Break zone densities were also regressed on topographical complexity to test for the effect of elevational variation. We found that two main break zones in the distribution of alleles and species were significantly correlated. Furthermore, we show that these break zones are in topographically complex regions, characterized by massive elevational ranges owing to high mountains and deep glacial valleys. We detected a third break zone in the distribution of species in the eastern Alps, which is not correlated with topographic complexity, and which is also not evident from allelic distribution patterns. Species with the potential for long-distance dispersal tended to show larger distribution ranges than short-distance dispersers. We suggest that the history of Pleistocene glaciations is the main driver of the congruence between allele-based and species-based distribution patterns, because occurrences of both species and alleles were subject to the same processes (such as extinction, migration and drift) that shaped the distributions of species and genetic lineages. Large elevational ranges have had a profound effect as a dispersal barrier for alleles during post-glacial immigration. Because plant species, unlike alleles, cannot spread via pollen but only via seed, and thus disperse less effectively, we conclude that species break zones are maintained over longer time spans and reflect more ancient patterns than allele break zones. [ABSTRACT FROM AUTHOR]

Understanding the natural history of model organisms is important for the effective use of their genomic resourses. Arabidopsis lyrata has emerged as a useful plant for studying ecological and evolutionary genetics, based on its extensive natural variation, sequenced genome and close relationship to A. thaliana. We studied genetic diversity across the entire range of European Arabidopsis lyrata ssp. petraea, in order to explore how population history has influenced population structure. We sampled multiple populations from each region, using nuclear and chloroplast genome markers, and combined population genetic and phylogeographic approaches. Within-population diversity is substantial for nuclear allozyme markers (mean P=0.610, Ae=1.580, He=0.277) and significantly partitioned among populations (FST=0.271). The Northern populations have modestly increased inbreeding (FIS=0.163 verses FIS=0.093), but retain comparable diversity to central European populations. Bottlenecks are common among central and northern Europe populations, indicating recent demographic history as a dominant factor in structuring the European diversity. Although the genetic structure was detected at all geographic scales, two clear differentiated units covering northern and central European areas (FCT =0.155) were identified by Bayesian analysis and supported by regional pairwise FCT calculations. A highly similar geographic pattern was observed from the distribution of chloroplast haplotypes, with the dominant northern haplotypes absent from central Europe. We conclude A. l. petraea's cold-tolerance and preference for disturbed habitats enabled glacial survival between the alpine and Nordic glaciers in central Europe and an additional cryptic refugium. While German populations are probable peri-glacial leftovers, Eastern Austrian populations have diversity patterns possibly compatible with longer-term survival. [ABSTRACT FROM AUTHOR]

There is an ongoing debate about the glacial history of non-arctic species in central and northern Europe. The two main hypotheses are: (1) postglacial colonization from refugia outside this region; (2) glacial survival in microclimatically favourable sites within the periglacial areas. In order to clarify the glacial history of a boreo-montane tall forb, we analysed AFLPs from populations of Cicerbita alpina through most of its range (Scandinavia, the mountains of central Europe, the Alps, the Pyrenees and the Balkan Peninsula). We found a major differentiation between the Pyrenean population and all others, supported by principal coordinate, neighbour joining and STRUCTURE analyses. Furthermore, three populations from the central and north-eastern Alps were genetically distinct from the bulk of populations from Scandinavia, central Europe, the Alps and the Balkan Peninsula. Most populations, including those from central and northern Europe, had moderate to high levels of genetic diversity (mean Shannon index HSh = 0.292, mean percentage of polymorphic loci P = 54.1%, mean Nei's gene diversity H = 0.195). The results indicate separate glacial refugia in the Pyrenean region and the Italian Alps. Furthermore, they provide evidence of glacial persistence in cryptic refugia north of the Alps, from where Scandinavia and most of the Alps are likely to have been colonized following deglaciation. © 2010 The Linnean Society of London, Botanical Journal of the Linnean Society, 2010, 164, 142-154. [ABSTRACT FROM AUTHOR]

Fourteen natural populations of Juniperus phoenicea L. from the quite entire species range have been compared using isoenzyme polymorphism. Among 17 loci, 5 ( Got1, 6Pgd3, Pgi2, Pgm2 and Shdh2) appeared to be differentiated sufficiently to provide useful information for discrimination between the subspecies phoenicea and turbinata (Guss.) Nyman. Two distinct groups of populations were detected using the Nei’s genetic distance unweighted pair group method with arithmetic mean (UPGMA) and discrimination analyses, one including the inland populations of the eastern Iberian Peninsula and southern France (subsp. phoenicea), and the second from the Mediterranean and Atlantic shores, and from the Atlas mountains in Africa (subsp. turbinata). The high level of differences confirms a long period of isolation, probably during the whole Pleistocene. The population from the Aegean Sea shore differed from the other Mediterranean shore plus Atlas mountain population. It also suggests spatial isolation between them, at least during the last Glaciation. [ABSTRACT FROM AUTHOR]

Amplified Fragment Length Polymorphism (AFLP) was used to clarify the glacial history of the rare, disjunctly distributed, alpine cushion plant Androsace wulfeniana , which is endemic to the Eastern Alps (Austria and Italy). Disjunct populations in the Dolomites are genetically very distinct from those in the main distributional area. It is hypothesized that they are descendants of long-term isolated glacial survivors and are not a result of recent long-­distance dispersal. Within the main distributional area of the species in the central Eastern Alps, two groups of ­populations can be distinguished, which are congruent with hotspots of rare relictual vascular plant taxa. In the ­taxonomically closely related A. brevis growing in the Southern Alps (Italy, Switzerland), no genetic-geographical structure was found. Genetic variation is extremely low in disjunct populations of A. wulfeniana in the Dolomites and in A. brevis . In contrast, in the main distributional area of A. wulfeniana , genetic variation is similar to that of the colonizing widespread congener A. alpina . © 2003 The Linnean Society of London, Botanical Journal of the ­Linnean Society , 2003, 141 , 437–446. [ABSTRACT FROM AUTHOR]

Abstract Polymerase chain reaction–restriction fragment length polymorphisms (PCR-RFLPs) and sequence analysis of noncoding regions of chloroplast DNA were used to investigate 37 populations of Eritrichium nanum covering its total distribution area, the European Alps. There was no haplotypic variation within the populations, and most haplotypes were restricted to single sites or to neighbouring populations, suggesting low levels of long distance gene flow via seeds. The present geographical distribution of haplotypes probably reflects an ancient geographical pattern within two regions in the intensely glaciated western and eastern central Alps identified as genetic hotspot areas. These two regions contained seven of the total of 11 haplotypes, including many of the most derived ones. The divergent haplotypes formed closely related groups, which supported a separate evolution of these haplotypes in these two regions and, more importantly, gave strong evidence for the in situ survival of these populations on nunataks within the western and eastern central Alps during Pleistocene glaciation. This result is in concordance with a previous study on E. nanum using nuclear markers. Only one haplotype was common and widespread throughout the distributional range of E. nanum . At the same time, it was the evolutionarily basal-most and all other haplotypes were best described as its descendants. This haplotype is hypothesized to be genetically identical to a Tertiary Alpine colonizing ancestor, whose distribution was secondarily fragmented and infiltrated by derived haplotypes originating through local mutations. [ABSTRACT FROM AUTHOR]

Genetic variation in seven relict populations of Saxifraga cernua from three regions of the Alps was investigated using RAPD (random amplified polymorphic DNA) markers. No variation, either within the populations or within the regions, could be demonstrated. Nevertheless, each alpine region was characterized by a unique RAPD phenotype. Absence of genetic variation in these relict populations is attributed to population bottlenecks and founder effects during or following the ice ages. Contrasting hypotheses about the history of these populations, either as survivors of the glacial period or as products of postglacial immigration, are discussed in the light of the data presented. [ABSTRACT FROM AUTHOR]

It has been suggested that many arctic-alpine plant species have limited dispersal ability and cannot have arrived in Scandinavia and the arctic archipelago of Svalbard by long-distance dispersal after a total glaciation. It has therefore been proposed that such species must have survived the entire glaciation(s) in ice-free refugia in southern Norway, northern Norway and Svalbard. We investigated random amplified polymorphic DNA (RAPD) variation among 28 populations from Norway and Svalbard of one of these arctic-alpine ‘short-distance dispersers’, the selfing polyploid Saxifraga cespitosa. In an analysis of molecular variance (AMOVA), more variation was found among populations within the three postulated refugia regions (45%) than among these regions (25%). Spatial autocorrelation (Mantel) analyses showed that the genetic distance monotonously increased with increasing geographical distance. In UPGMA and PCO analyses, the populations from Norway and Svalbard formed a south–north cline that continued across the Barents Sea barrier. The results suggest that there has been recent dispersal among the three postulated refugia regions and thus that postglacial dispersal into these refugia regions from other distant areas also must represent a possibility. The observed geographical pattern of the genetic variation may have been established after expansion from different source areas outside the North European ice sheet and/or from different refugia areas ‘within’ the ice sheet, but it is probably not possible to distinguish among these alternatives. The results for S. cespitosa are consistent with a dynamic late- and postglacial scenario with extensive plant dispersal, and support the conclusion from our previous study of the outbreeding Saxifraga oppositifolia; the hypothesis of glacial survival in Norway and/or Svalbard is superfluous. [ABSTRACT FROM AUTHOR]

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) varaition 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 (AMOVA), most of the RAPD variation was found within populations (64%). There was less intrapopulational varaition 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 clinical 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 continuosly distributed populations of S. oppositifolia during the Weichselian, and the extant Nordic population 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. [ABSTRACT FROM AUTHOR]

Andøya on the NW coast of Norway is a key site for understanding the Last Glacial Maximum (LGM) in northern Europe. Controversy has arisen concerning the local conditions, especially about the timing and extent of local glacial cover, maximum July temperatures and whether pine and/or spruce could have grown there. We reviewed all existing data and add newly analysed ancient sedimentary DNA (seda DNA), pollen, macrofossils, geochemistry and stable isotopes from three lake sediment cores from Øvre Æråsvatnet. A total of 23 new dates and age-depth modelling suggests the lake has been ice-free since GI2 (<23.4 cal ka BP) and possibly GS3 (<26.7 cal ka BP). Pinus and Picea seda DNA was found in all three cores but at such low frequencies that it could not be distinguished from background contamination. LGM samples have an exceptionally high organic matter content, with isotopic values indicating that carbon and nitrogen derive from a marine source. Along with finds of bones of the little auk (Alle alle), this indicates that the lake received guano from an adjacent bird colony. Seda DNA, pollen and macrofossil assemblages were dominated by Poaceae, Brassicaceae and Papaver , but scattered occurrence of species currently restricted to the Low Arctic Tundra Zone (July temperature of 8–9 °C) such as Apiaceae (seda DNA, 8–9 °C), and Alchemilla alpina (macrofossil, 8–9 °C) were also recorded. The review of >14.7 cal ka BP data recorded 94 vascular plant taxa, of which 38% have a northern limit in Shrub Tundra or more southern vegetation zones. This unusual assemblage likely stems from a combination of proximity to ice-free water in summer, geographical isolation linked with stochastic long-distance dispersal events, and the presence of bird-fertilized habitats. The environmental reconstruction based on all records from the area does not preclude local growth of tree species, as the local climate combined with high nutrient input may have led to periodically suitable environmental 'hotspot' conditions. • High organic content of Last Glacial Maximum sediments from a northern refugium. • Isotopes and bones indicate birds roosted near the ice edge. • Conifer DNA found in sediments, but frequency not significantly above background contamination. • Review of all Andøya LGM studies reveals presence of boreal and arctic taxa. • Environmental reconstruction does not preclude intermittent growth conditions for trees. [ABSTRACT FROM AUTHOR]

• Glacial survival of Astragalus onobrychis within the Pannonian region. • Pleistocene E–W expansion from the Pontics/Caucasus into Pannonian region (8x). • Younger, smaller-scaled postglacial W–E migration across the Pannonian region. • Long-term stable populations in Dobruja, N Balkan & Central Pontic subregions. • High genetic uniqueness of S Pannonian, N Balkan and N Caucasus populations. Steppe grasslands represent important refuges for rare species in the Pannonian region of eastern Central Europe. Nevertheless, little is known about their regional continuity and potential (post)glacial in-situ survival. Biogeographical studies assume potential source areas for the postglacial (re)colonisation of the Pannonian region in the Western and Central Pontics including the Black Sea coast. However, south-exposed slopes surrounding the Hungarian plain may have also played an important role as small-scale refugia. Using cpDNA sequence markers (atpI-H , rpL16, ycf1) and 190 individuals representing 25 populations, we investigated the genetic diversity and biogeographical history of Astragalus onobrychis within different subregions of its European distribution. We aimed at answering questions about the glacial survival, (post)glacial expansion and/or recent decline of the species throughout this area. A TCS network showed 108 haplotypes, which were divided into two unconnected clusters, representing different ploidy levels. We found octoploid populations widely distributed from the Pannonian region and Transylvania to more eastern areas in the Western Pontics and the Northern Caucasus. On the contrary, di- and tetraploid populations occur in the Dobruja and the Northern Balkan Peninsula, but also in the Central Pontic and the Southern Pannonian subregions. Four main cpDNA haplotype groups basically showed a geographical pattern; the Pannonian region being best-defined. We found high haplotype and moderate to high nucleotide diversity within most populations/subregions. Equilibrating these two genetic diversity measures indicates a long-term – probably glacial – (diploid) persistence of A. onobrychis in the Southern Pannonian subregion, areas along the Black Sea coast, the Northern Balkan Peninsula and the Central Pontic subregion. However, the octoploid lineage likely originated more to the east and expanded to Western Pontic areas and the Pannonian Basin probably already during Pleistocene. [ABSTRACT FROM AUTHOR]

The early observation from 1914 of Tanymastix stagnalis in Norway was not repeated recently, showing a rare and restricted distribution of this species. All four sampled localities were concentrated in the same area of the Trollheimen Mountains with altitudes of 900-1244 m above sea level. In March 2002, a new population of T. stagnalis was observed at about 50 km north of Madrid at an altitude of 1350 m. In general, all habitats with T. stagnalis were fishless shallow ponds and varied in size from 1 to about 300 m(2). Natural variability of the global temperature is well accepted, but recent climate models have predicted increases in global average temperature. Based on the new biogeographical distribution, diurnal temperature variations, and biological evidence (inference with the analysis of mitochondria DNA), the immigration history of T. stagnalis was considered on the basis of two opposing immigration theories and in relation to the implications of global climate change. Two immigration theories, namely - the Tabula rasa and Nunatak, have prevailed in explaining the present distribution of plants and animals in Scandinavia. It was concluded that the rare occurrence of T. stagnalis in Norway fits into the Nunatak theory and that the species probably survived, at least, the last glaciation on Nunataks or coast refuges located in central northwestern Norway at Møre mountain and coast areas.