Papers by Galina Gussarova
Quaternary Science Reviews, 2015
High Arctic environments are particularly sensitive to climate changes, but retrieval of paleoeco... more High Arctic environments are particularly sensitive to climate changes, but retrieval of paleoecological data is challenging due to low productivity and biomass. At the same time, Arctic soils and sediments have proven exceptional for long-term DNA preservation due to their constantly low temperatures. Lake sediments contain DNA paleorecords of the surrounding ecosystems and can be used to retrieve a variety of organismal groups from a single sample. In this study, we analyzed vascular plant, bryophyte, algal (in particular diatom) and copepod DNA retrieved from a sediment core spanning the Holocene, taken from Bliss Lake on the northernmost coast of Greenland. A previous multi-proxy study including microscopic diatom analyses showed that this lake experienced changes between marine and lacustrine conditions. We inferred the same environmental changes from algal DNA preserved in the sediment core. Our DNA record was stratigraphically coherent, with no indication of leaching between layers, and our cross-taxon comparisons were in accordance with previously inferred local ecosystem changes. Authentic ancient plant DNA was retrieved from nearly all layers, both from the marine and the limnic phases, and distinct temporal changes in plant presence were recovered. The plant DNA was mostly in agreement with expected vegetation history, but very early occurrences of vascular plants, including the woody Empetrum nigrum, document terrestrial vegetation very shortly after glacial retreat. Our study shows that multitaxon metabarcoding of sedimentary ancient DNA from lake cores is a valuable tool both for terrestrial and aquatic paleoecology, even in low-productivity ecosystems such as the High Arctic.
Botanical Journal of the Linnean Society, Jun 1, 2007
The lectotype for Euphrasia hirtella var. ramosa is selected. This taxon and E. hirtella var. kar... more The lectotype for Euphrasia hirtella var. ramosa is selected. This taxon and E. hirtella var. karoiana are compared with E. amurensis and confirmed as synonyms, corroborating Juzepcuk (1955).
Trees-structure and Function, Sep 17, 2016
Key Message The modelling showed that outer ledges prevent wide opening of the stomatal pore and ... more Key Message The modelling showed that outer ledges prevent wide opening of the stomatal pore and its lifting above leaf epidermis. This stomatal mechanics is combined with xeromorphic features of leaf epidermis. Abstract Methods of light, scanning, and transmission electron microscopy were used to study the stomata of the leaf epidermis in evergreen Acokanthera oblongifolia (Apocynaceae), A. oppositifolia (Apocynaceae), Carissa spectabilis (Apocynaceae), Exbucklandia populnea (Hamamelidaceae), and Trochodendron aralioides (Trochodendraceae). The stomata of their leaf epidermis are located on subsidiary cells, have large outer ledges, and lack inner ledges. To elucidate the role of the ledges, we applied dynamic modelling using the finite-element method. The application of dynamic modelling has shown that outer ledges prevent wide opening of the stomatal pore and their rising above the surface of leaf epidermis. The results of the modelling are supported by the observed deformations in the guard cells of the real stomata. This stomatal mechanics is combined with such stomatal xeromorphic features as thick cuticle, stomatal cavities, and waxy plugs (in A. oblongifolia). All studied species show similar leaf anatomy. It has much in common with the leaf anatomy of species connected in their origin with subhumid Tertiary laurophyllous forests.
Taxon, Aug 1, 2011
This is the first comprehensive molecular investigation of the genus Lamium L. We have addressed ... more This is the first comprehensive molecular investigation of the genus Lamium L. We have addressed phylogenetic relationships and presumed allopolyploid speciation by use of nuclear (NRPA2, 5S-NTS) and chloroplast (matK, psbA-trnH, rps16, trnL, trnL-F, trnS-G) DNA sequence data. Nuclear and chloroplast data were incongruent, and nuclear data showed better correlation with morphology. Bayesian and parsimony phylogenetic results show that (1) Lamium galeobdolon is sister to all remaining Lamium species; (2) Wiedemannia is nested within Lamium; (3) L. amplexicaule is polyphyletic; (4) most tetraploids are of hybrid origin; (5) L. amplexicaule var. orientale is allotetraploid; and (6) Mennema's (1989) infrageneric classification is not corroborated by molecular data. Based on the molecular results, and taking morphology into account, we suggest resurrection of two species: L. aleppicum and L. paczoskianum.
Molecular Phylogenetics and Evolution, Nov 1, 2010
by a long period of nonet diversification, likely due to extinctions caused by a Late Eocene to M... more by a long period of nonet diversification, likely due to extinctions caused by a Late Eocene to Miocene dramatic reduction in rainforest cover. A Late Miocene to Early Pliocene rise in sea-level probably caused the vicariant diversification observed between areas of endemism. The most recent species divergences are concordant with Pleistocene changes in climate and sea-levels, but apparently with no successful inter-area migrations, supportive of savannah, rather than rainforest, covered landbridges. An explosive increase in net diversification rate, most pronounced in Rafflesia, may be explained by Mid-Miocene to Pliocene rainforest-favorable conditions as well as natural selection promoting character displacement for Rafflesia flower size.
Isotopes in Environmental and Health Studies, May 15, 2014
Sources of variation in small rodent trophic niche: new insights from DNA metabarcoding and stabl... more Sources of variation in small rodent trophic niche: new insights from DNA metabarcoding and stable isotope analysis Intraspecific competition for food is expected to increase the trophic niche width of consumers, defined here as their diet diversity, but this process has been little studied in herbivores. Population densities of small rodents fluctuate greatly, providing a good study model to evaluate effects of competition on trophic niche. We studied resource use in five arctic small rodent populations of four species combining DNA metabarcoding of stomach contents and stable isotope analysis (SIA). Our results suggest that for small rodents the most pronounced effect of competition on trophic niche is due to increased use of secondary habitats and to habitat-specific diets, rather than an expansion of trophic niche in primary habitat. DNA metabarcoding and SIA provided complementary information about the composition and temporal variation of herbivore diets. Combing these two approaches requires caution, as the underlying processes causing observed patterns may differ between methodologies due to different spatiotemporal scales.
American Journal of Botany, Oct 1, 2015
Many arctic-alpine species have vast geographic ranges, but these may encompass substantial gaps ... more Many arctic-alpine species have vast geographic ranges, but these may encompass substantial gaps whose origins are poorly understood. Here we address the phylogeographic history of Silene acaulis , a perennial cushion plant with a circumpolar distribution except for a large gap in Siberia. METHODS: We assessed genetic variation in a range-wide sample of 103 populations using plastid DNA (pDNA) sequences and AFLPs (amplifi ed fragment length polymorphisms). We constructed a haplotype network and performed Bayesian phylogenetic analyses based on plastid sequences. We visualized AFLP patterns using principal coordinate analysis, identifi ed genetic groups using the program structure, and estimated genetic diversity and rarity indices by geographic region. KEY RESULTS: The history of the main pDNA lineages was estimated to span several glaciations. AFLP data revealed a distinct division between Beringia/ North America and Europe/East Greenland. These two regions shared only one of 17 pDNA haplotypes. Populations on opposite sides of the Siberian range gap (Ural Mountains and Chukotka) were genetically distinct and appear to have resulted from postglacial leading-edge colonizations. We inferred two refugia in North America (Beringia and the southern Rocky Mountains) and two in Europe (central-southern Europe and northern Europe/East Greenland). Patterns in the East Atlantic region suggested transoceanic long-distance dispersal events. CONCLUSIONS: Silene acaulis has a highly dynamic history characterized by vicariance, regional extinction, and recolonization, with persistence in at least four refugia. Long-distance dispersal explains patterns across the Atlantic Ocean, but we found no evidence of dispersal across the Siberian range gap. KEY WORDS AFLP; arctic-alpine; Caryophyllaceae; disjunct distribution; phylogeography; psbD-trnT (GGU) spacer; rpL32-trnL (UAG) spacer; Silene acaulis ; trn L (UAA) intron; trnL (UAA)-trnF (GAA) spacer; refugia
Taxon, Feb 1, 2012
The high-arctic environment supports very few annual plants, but more annuals can be expected to ... more The high-arctic environment supports very few annual plants, but more annuals can be expected to move northwards following climate warming. Here we address the history of the amphi-Atlantic, hemiparasitic Euphrasia minima complex, which is taxonomically intricate and consists of annuals typically growing in alpine, north boreal, and low-arctic habitats. Recently it has also been discovered at three distantly separated sites in the high-arctic archipelago of Svalbard. We analyzed Amplified Fragment Length Polymorphism (AFLP) and chloroplast DNA (cpDNA) variation in populations from most of the range of the complex. The main split observed in both datasets, dated to nearly 6 Ma ago, was between one central/southern European alpine lineage (E. minima s.str.) and one northern amphi-Atlantic lineage (E. wettsteinii). The E. wettsteinii lineage consisted of two cpDNA sublineages, both amphi-Atlantic and partly sympatric, estimated to have diverged 1.7 Ma ago. Two main northern subgroups were also revealed in the AFLP dataset, partly consistent with the cpDNA sublineages: one E Atlantic subgroup (N Russia, extending into Scotland and Colesdalen in Svalbard), and one mainly W Atlantic subgroup (NE Canada, Greenland, and Iceland, extending into N Norway). A third subgroup was restricted to two of the three Svalbard populations, Bockfjorden and Ossian Sarsfjellet. Assignment tests of the Svalbard populations suggest that Colesdalen was derived from N Russian source populations and Bockfjorden from N Norwegian ones; the assignment of the Ossian Sarsfjellet population was uncertain. However, as all Svalbard populations were distinctly divergent from each other as well as from all other populations in AFLP marker frequencies, it is unlikely that their establishment in Svalbard is caused by the current climate warming or recent human activities. Their divergence is probably due to founder effects and genetic drift following independent earlier immigrations, possibly during the postglacial warm period 9500 to 4000 years ago.
Journal of Biogeography, Jun 25, 2012
Aim Based on extensive range-wide sampling, we address the phylogeographical history of one of th... more Aim Based on extensive range-wide sampling, we address the phylogeographical history of one of the most widespread and taxonomically complex sedges in Europe, Carex nigra s. lat. We compare the genetic structure of the recently colonized northern areas (front edge) and the long-standing southern areas (rear edge), and assess the potential genetic basis of suggested taxonomic divisions at the rank of species and below. Location Amphi-Atlantic, central and northern Europe, circum-Mediterranean mountain ranges, central Siberia, Himalayas. Methods A total of 469 individuals sampled from 83 populations, covering most of the species' range, were analysed with amplified fragment length polymorphism (AFLP) and chloroplast DNA (cpDNA) markers. Bayesian clustering, principal coordinates analysis, and estimates of diversity and differentiation were used for the analysis of AFLP data. CpDNA data were analysed with statistical parsimony networks and maximum parsimony and Bayesian inference of phylogenetic trees. Results Overall genetic diversity was high, but differentiation among populations was limited. Major glacial refugia were inferred in the Mediterranean Basin and in western Russia; in addition, there may have been minor refugia in the North Atlantic region. In the southern part of the range, we found high levels, but geographically quite poorly structured genetic diversity, whereas the levels of genetic diversity varied among different areas in the north. North American populations were genetically very similar to the European populations. Main conclusions The data are consistent with extensive gene flow, which has obscured the recent history of the taxon. The limited differentiation in the south probably results from the mixing of lineages expanding from several local refugia. Northward post-glacial colonization resulted in a leading-edge pattern of low diversity in the Netherlands, Belgium, Scotland and Iceland, whereas the observed high diversity levels in Fennoscandia suggest broad-fronted colonization from the south as well as from the east. The patterns found in the American populations are consistent with post-glacial colonization, possibly even with anthropogenic introduction from Europe. Our data also suggest that the tussock-forming populations of C. nigra, often referred to as a distinct species (Carex juncella), represent an ecotype that has originated repeatedly from different populations with creeping rhizomes.
Dendrobiology, Nov 12, 2020
Norway spruce (Picea abies) and Siberian spruce (P. obovata) are among the most important forest-... more Norway spruce (Picea abies) and Siberian spruce (P. obovata) are among the most important forest-forming coniferous species in the boreal part of Eurasia. Despite numerous publications on the taxonomy of Norway spruce and closely related taxa (P. obovata Ledeb. and P. fennica (Regel) Kom.), the problem of their identification, as well as clarification of their taxonomic status, has not been solved so far. Species delimitation is particularly challenging when P. abies, P. obovata and P. fennica occur in sympatry. Our study aims to assess taxonomic value of proposed earlier and search for stable diagnostic characters of cones and their scales to distinguish Picea abies and its sympatric in the NorthWest of Russia P. fennica and P. obovata. In addition, we analyzed and updated information on geographical distribution and phytocenotic characteristics of the above-mentioned species in the NorthWest of the European part of Russia. We examined herbarium specimens and cones sampled from 88 trees from 22 Picea stands located throughout the study region. Each tree was represented on average by 5 cones, in total 415 cones were analyzed. Morphometric analyses included 16 morphological characters of cones and their scales selected based on our own observations and published data. Multivariate comparison had shown a large overlap between P. obovata and P. fennica, while individuals of P. abies formed a separate and less overlapping cluster. Among the six qualitative (discrete) characters, shape of seed scale and shape of its upper margin have non-overlapping frequency distributions and can separate P. abies and P. obovata. Several new diagnostic characters are proposed: morphology and size of bract scales and ratio of the size of seed scales and bract scales. Phytocenotic analysis showed that different spruce taxa occupy specific habitats, which in their turn connected with the latitudinal gradient: in normally drained habitats, Picea obovata is found mainly in poor shrubby-green-mossy forests, which are typical of the northern and middle parts of the Northern taiga; Picea abies-in richer green-mossy habitats (Vaccinioso-hylocomiosum, Oxalidoso-hylocomiosum, Hylocomiosum), which begin to occur already from the middle part of the Northern taiga. Picea fennica occupies both habitats.
Molecular Phylogenetics and Evolution, Aug 1, 2008
Euphrasia includes perennial or annual green parasitic plants, and has a disjunct bipolar distrib... more Euphrasia includes perennial or annual green parasitic plants, and has a disjunct bipolar distribution except for one transtropical connection across the high mountains of Oceania. The disjunction is coupled with strikingly contrasting patterns of morphological diversity between the southern and northern hemispheres, making it an exciting model to study processes of evolutionary diversification which shaped present floras. We inferred the relationships among 51 species representing 14 of the 15 sections of the genus based on nrDNA ITS and cpDNA trnL intron, trnL-trnF and atpB-rbcL intergenic spacers. Maximum parsimony and Bayesian inference support monophyly of the genus and of several intrageneric groups characterized by morphology, ploidy level, and geographic range. Molecular phylogenetic dating using Bayesian ''relaxed" clock methods suggests that the earliest Euphrasia radiations occurred minimum 11-8 Mya with bipolarity being achieved 7-5 Mya. Biogeographic analyses using explicit modelbased approach inferred Eurasia as an ancestral area for the genus. The most parsimonious reconstruction found by a dispersal-vicariance analysis requires 17 dispersals to account for the current biogeographic pattern and supports Eurasian origin for Euphrasia. Both long-distance dispersal and across land vicariance can be invoked to explain the diversification in the genus, which experienced rapid radiations driven by new ecological opportunities of the late Pliocene and Pleistocene but also retained a set of local endemic or relict species of an earlier origin.
Frontiers in Plant Science, May 27, 2022
Flora, May 1, 2018
Highlights We described lipid droplets in the cells of stomatal complex in Trochodendron. We ... more Highlights We described lipid droplets in the cells of stomatal complex in Trochodendron. We found breakdown of large lipid droplets in the cells of stomatal complex. Breakdown of lipid droplets can be used to maintain stable stomatal functioning.
Flora, Mar 1, 2016
Large lipid droplets are present constantly in the leaf epidermis of angiosperms. Earlier they ... more Large lipid droplets are present constantly in the leaf epidermis of angiosperms. Earlier they were considered typical only of mesophyll and bundle-sheath cells. Now they are found in stomata, in particular, in their subsidiary cells. We observed that breakdown of large lipid droplets takes place in dying leaves. We suggest that lipids from lipid droplets are used to maintain functionality of stomata.
Annals of Botany, Oct 13, 2021
Background and Aims The Arctic tundra, with its extreme temperatures and short growing season, is... more Background and Aims The Arctic tundra, with its extreme temperatures and short growing season, is evolutionarily young and harbours one of the most species-poor floras on Earth. Arctic species often show little phenotypic and genetic divergence across circumpolar ranges. However, strong intraspecific post-zygotic reproductive isolation (RI) in terms of hybrid sterility has frequently evolved within selfing Arctic species of the genus Draba. Here we assess whether incipient biological species are common in the Arctic flora. • Methods We conducted an extensive crossing experiment including six species representing four phylogenetically distant families collected across the circumpolar Arctic. We crossed conspecific parental populations representing different spatial scales, raised 740 F 1 hybrids to maturity and measured fertility under laboratory conditions. We examined genetic divergence between populations for two of these species (Cardamine bellidifolia and Ranunculus pygmaeus). • Key Results In five of the six species, we find extensive reduction in pollen fertility and seed set in F 1 hybrids; 219 (46 %) of the 477 F 1 hybrids generated between parents separated by ≥427 km had <20 % pollen fertility. Isolation with migration (IM) and *BEAST analyses of sequences of eight nuclear genes in C. bellidifolia suggests that reproductively isolated populations of this species diverged during, or even after, the last glaciation. Likewise, Arctic populations of R. pygmaeus were genetically very similar despite exhibiting strongly reduced fertility in crosses, suggesting that RI evolved recently also in this species. • Conclusion We show that post-zygotic RI has developed multiple times within taxonomically recognized Arctic species belonging to several distantly related lineages, and that RI may have developed over just a few millennia. Rapid and widespread evolution of incipient biological species in the Arctic flora might be associated with frequent bottlenecks due to glacial cycles, and/or selfing mating systems, which are common in the harsh Arctic environment where pollinators are scarce.
Application of molecular markers in plant systematics led to the development of independent disci... more Application of molecular markers in plant systematics led to the development of independent disciplines: molecular phylogenetics and phylogeography. They use genetic information (DNA sequences) to infer history of species and populations. This includes reconstruction of kinship, i.e. phylogenetic relationships, conclusions about directions of historical migrations, estimation of divergence time, inferences of demographic processes in ancestral populations etc. Using examples of flowering plants of various taxonomic ranks, one family, two genera and three species, we discuss the main questions addressed by phylogenetics and phylogeography, the key methodological approaches and methods of data analysis. All the projects described in the paper have been realized with the author’s participation at the National Centre for Biosystematics, Natural History Museum, University of Oslo (Norway).
The unique P6 loop trnL sequences produced by amplification of DNA with the primers trnL_g and tr... more The unique P6 loop trnL sequences produced by amplification of DNA with the primers trnL_g and trnL_h as detailed in the associated publication. The data was recovered from DNA preserved in a sediment core spanning the Holocene from Bliss Lake, Peary Land, North Greenland. These sequences were recovered in the first round of amplification and sequencing of vascular plant DNA, as detailed in the associated publication (vascular plant dataset 1, "vp1"). Taxonomic identification of sequences was inferred using a compilation of quality-checked and curated reference libraries for arctic and boreal species constructed at the Natural History Museum in Oslo (arctic vascular plants: Sønstebø et al. 2010; boreal vascular plants: Willerslev et al. 2014; bryophytes: Soininen et al. 2015). Further details can be found in the ReadMe file
The unique P6 loop trnL sequences produced by amplification of DNA with the primers bryo_P6F_1* &... more The unique P6 loop trnL sequences produced by amplification of DNA with the primers bryo_P6F_1* & bryo_P6R as detailed in the associated publication. The data was recovered from DNA preserved in a sediment core spanning the Holocene from Bliss Lake, Peary Land, North Greenland. Taxonomic identification of sequences was inferred using a compilation of quality-checked and curated reference libraries for arctic and boreal species constructed at the Natural History Museum in Oslo (arctic vascular plants: Sønstebø et al. 2010; boreal vascular plants: Willerslev et al. 2014; bryophytes: Soininen et al. 2015). Further details can be found in the ReadMe file
High Arctic environments are particularly sensitive to climate changes, but retrieval of paleoeco... more High Arctic environments are particularly sensitive to climate changes, but retrieval of paleoecological data is challenging due to low productivity and biomass. At the same time, Arctic soils and sediments have proven exceptional for long-term DNA preservation due to their constantly low temperatures. Lake sediments contain DNA paleorecords of the surrounding ecosystems and can be used to retrieve a variety of organismal groups from a single sample. In this study, we analyzed vascular plant, bryophyte, algal (in particular diatom) and copepod DNA retrieved from a sediment core spanning the Holocene, taken from Bliss Lake on the northernmost coast of Greenland. A previous multi-proxy study including microscopic diatom analyses showed that this lake experienced changes between marine and lacustrine conditions. We inferred the same environmental changes from algal DNA preserved in the sediment core. Our DNA record was stratigraphically coherent, with no indication of leaching between layers, and our cross-taxon comparisons were in accordance with previously inferred local ecosystem changes. Authentic ancient plant DNA was retrieved from nearly all layers, both from the marine and the limnic phases, and distinct temporal changes in plant presence were recovered. The plant DNA was mostly in agreement with expected vegetation history, but very early occurrences of vascular plants, including the woody Empetrum nigrum, document terrestrial vegetation very shortly after glacial retreat. Our study shows that multi-taxon metabarcoding of sedimentary ancient DNA from lake cores is a valuable tool both for terrestrial and aquatic paleoecology, even in low-productivity ecosystems such as the High Arctic
Fasta file of the Arctic reference database (ITSCyp
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Papers by Galina Gussarova