Search

The grass Deschampsia cespitosa is a variable taxon out of which many varieties, subspecies and endemic species have been separated. In this paper, the variation in genome size (GS) and ploidy of this grass including several of its subspecies and two related species in Eurasia was investigated by flow cytometric (FCM) measurements. GS and ploidy data were also related to specific environments and reproduction mode. Ploidy levels found by FCM were confirmed by chromosome counts of diploid (2n = 28) and tetraploid (2n = 52) samples. Seminiferous (seed bearing) D. cespitosa was mainly diploid (GS between 3.754 and 5.438 pg/1C). GS variation in diploids showed a geographic pattern with a significant difference (H = 41,441, P < 0.001) between European (median = 4.377 pg) and Asian (median = 4.881 pg) accessions. Genome size (1C) in tetraploids ranged from 7.9426 to 9.0399 pg. Tetraploid seminiferous D. cespitosa was found mostly in disturbed habitats in western and southern Europe, while tetraploids in Asia were registered in wet Arctic habitats. Genome size (1C between 8.3278 and 8.8603 pg) of the pseudoviviparous plants (spikelets produce plantlets asexually) of wet habitats in central and northern Europe indicated tetraploidy. A putative triploid (GS 6.6817 pg) was detected in Iceland. Summing up, we found a high variation in GS on the geographic scale with significant regional differences in diploid D. cespitosa. Among the tetraploids, the asexually reproducing plants were bound to specific habitats, while the seminiferous plants showed a habitat preference similar to the diploids. [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]

Helianthemum nummularium s.l. is a young, morphologically diverse species distributed from western Europe to the Caucasus and the Southern Urals in the east. We analysed the rps16- trnK plastid intergenic spacer sequences from 85 localities covering most of the range of H. nummularium. Thirteen haplotypes were very unevenly distributed throughout the range of the species, and exhibited a strong phylogeographic signal. The results confirm range expansions of H. nummularium from Mediterranean refugia northwards, but also show the major role of eastern European (the Caucasus and the Southern Urals) refugia in rapid postglacial colonization of east, north and central Europe. The plastid haplotypes form distinct clades, one representing an eastern European lineage with few haplotypes and the other representing a western European lineage with many haplotypes. Parallel to this split in haplotype diversity is the pronounced differentiation in morphological variation displayed by the taxa found in west and east Europe. We discuss the role of topography in generating differences in morphological and genetic diversity between these two groups. We also discuss the taxonomical status of Helianthemum arcticum, which is regarded as an endangered local endemic of the Kola Peninsula. Helianthemum arcticum appears to represent an outlying peripheral population of H. nummularium preserved since the last postglacial major range expansion of this species, and bears the same plastid haplotype as the bulk of east and north European populations. [ABSTRACT FROM AUTHOR]

Primula vulgaris exhibits flower colour polymorphism in the eastern part of its range, especially pronounced on the NE coast of the Black Sea. This polymorphism in the Caucasian populations has been taxonomically described and some segregated species are listed as rare and endangered. We used sequence variation in two chloroplast noncoding regions ( trnL- trnF and rpll32- trnL) and the complete nuclear internal transcribed spacer (ITS) of ribosomal DNA region to investigate correspondence between flower colour and geographical distribution of both nuclear and chloroplast haplotypes. It appears that variability in these DNA regions does not correlate with flower colour, being, however, clearly structured geographically. We used nested clade analysis to explore this geographical structure. It seems that the territory of the Colchis refugium on the E coast of the Black Sea contains both the highest flower colour and haplotype diversities. The results suggest that common primroses colonized the NE coast of the Black Sea from this refugium, spreading along the coast westward. At the same time, the analysis of ITS haplotypes indicates that P. vulgaris colonized the Crimea from NW Anatolia. This makes it clear that no segregated species can be recognized within flower colour polymorphic P. vulgaris in the Caucasus region. However, its phylogeography needs further detailed study on a broader scale. [ABSTRACT FROM AUTHOR]