Colobanthus Quitensis Research Articles

Комплексна характеристика району Аргентинських островів та острова Галіндез (Морська Антарктика) як полігону для вивчення динаміки наземної рослинності

The aim of this research was generalization of base information about study area – Argentine Islands and detail characteristic of terrestrial biotopes by description and mapping of landscape elements, surface waters, and general vegetation for the chosen monitoring area of Galindez Island realized during the seasons of 2014, 2016, 2017. We also characterized animal and anthropogenic effects on the distribution of the different vegetation types. In this research a number of methods of field investigation and mapping with ArcGIS is used. Results. It was shown that most types of the available vegetation are predominantly distributed on those landscape elements, which rise above the permanent snow level, as well as get free from the snow the earliest during the summer, or they are not covered with snow in the winter. Various vegetation types can be formed here from the most sensitive to the duration of the vegetative period, e.g. communities with vascular plants, to the most tolerant to prolonged staying under snow, e.g. crustose lichens. This effect depends on the height and the sunlight availability, the duration of snow-free period on it, as well as humidity, the distance from the sea and the flow of organic matter from the sea birds. At present, in the area of the Argentine Islands in general, and on the Galindez Island in particular, the expansion of Pygoscelis papua (Spheniscidae) is observed, which has already led to the degradation of typical vegetation types in the area where these colonies had originated. The limited input of organic matter from the seabirds contributes to the development of moderately nitrophilic groups, whereas the use of these plants and lichens as the nest material leads to the distribution of vegetation in the region. The largest anthropogenic transformation occurred in the area when the station complex was built. At present, the populations of Deschampsia antarctica (Poaceae) are being formed in the area, shielded by the construction elements, which also contribute to the recolonization of certain species of scalloped lichens, but only on oldest constructions of Вritish period 1954—1996. Conclusions. It’s necessary: to continuation of monitoring of the influence of natural and anthropogenic factors on vegetation of the region; Limitation of the scientific collection of rare species, in particular Colobanthus quitensis (Caryophyllaceae); Creation of new nature protected areas with a regime of strict protection (Ia IUCN) based on the allocation of sites with the highest biodiversity valuable for monitoring in non-intervention; Additional explanatory activity on the value and vulnerability of the terrestrial ecosystems in the region.

Positive interactions among native and invasive vascular plants in Antarctica: assessing the “nurse effect” at different spatial scales

Antarctica is a stressful ecosystem with few vascular plants, an ideal system to test positive interactions. Here, plants such as Deschampsia antarctica could generate more suitable micro-environmental conditions for the establishment of other plants (facilitation). We examined the co-occurrence of vascular plant species in the Antarctic Peninsula and assessed the potential nurse effect by D. antarctica on the native Colobanthus quitensis and the invasive Poa annua. We also measured the ecophysiological performance and survival of C. quitensis within and outside the canopy of D. antarctica in two study sites differing in stress levels. In addition, a survival experiment was conducted with the invasive Poa annua individuals within and outside D. antarctica individuals. In sites where present, target species co-occurred with D. antarctica in both Shetland Islands and Antarctic Peninsula. In agreement with the stress gradient hypothesis, we found evidence of facilitation between vascular Antarctic plant species. Specifically, we found that D. antarctica facilitates the native C. quitensis and the invasive P. annua and that the effect is stronger in more stressful sites. Additionally, C. quitensis distribution is compatible with an influence of either direct or indirect facilitation from D. antarctica. Facilitation between vascular plants may play a role structuring Antarctic plant communities. Thus, distribution of native species should be considered when assessing the introduction and spread of invasive species. Also, our results together with those from previous studies showed that the type and magnitude of biotic interactions may change with time and can depend on the plant traits considered.

Antarctic pearlwort (Colobanthus quitensis) populations respond differently to pre-germination treatments

Seed germination depends on various biotic and abiotic interactions associated with maternal habitat. The formation of soil seed banks is a key strategy and has ecological implications, especially with regard to species that develop in extreme habitats. When establishing germplasm banks of these species from seeds, seed dormancy becomes one of the main difficulties. In this research, we study Colobanthus quitensis, a species with wide latitudinal and altitudinal distribution, inhabiting extreme environments from southern Mexico to maritime Antarctica. Furthermore, this species has been described to have a secondary dormancy that is dependent on the environment. In order to perform research without needing to have regular access to this species’ habitats, it is therefore vital to possess plant material from different populations representing the species distribution. Thus, we evaluated the effects of various pre-germination treatments on germination percentage and time in four populations of the species. A differential and significant effect was evidenced, both among treatments and populations. Acid scarification increased germination percentage and decreased germination time. The best treatments were determined by population, and direct seeding after a brief period of cold stratification (4 °C) allowed us to achieve good germination percentages in at least three of the studied populations. This new evidence allows optimization in the introduction, development, characterization, and availability of plant material of the different C. quitensis populations in the Antarctic Vascular Plant Germplasm Bank.

Contrasting thermal acclimation of leaf dark respiration and photosynthesis of Antarctic vascular plant species exposed to nocturnal warming.

Leaf respiration and photosynthesis will respond differently to an increase in temperature during night, which can be more relevant in sensitive ecosystems such as Antarctica. We postulate that the plant species able to colonize the Antarctic Peninsula-Colobanthus quitensis (Kunth) Bartl. and Deschampsia antarctica Desv.-are able to acclimate their foliar respiration and to maintain photosynthesis under nocturnal warming to sustain a positive foliar carbon balance. We conducted a laboratory experiment to evaluate the effect of time of day (day and night) and nocturnal warming on dark respiration. Short (E0 and Q10 ) and long-term acclimation of respiration, leaf carbohydrates, photosynthesis (Asat ) and foliar carbon balance (R/A) were evaluated. The results suggest that the two species have differential thermal acclimation respiration, where D. antarctica showed more thermosensitivity to short-term changes in temperature than C. quitensis. Experimental nocturnal warming affected respiration at daytime differentially between the two species, with a significant increase of R10 and Asat in D. antarctica, while no changes on respiration were observed in C. quitensis. Long thermal treatments of the plants indicated that nocturnal but not diurnal respiration could acclimate in both species, and to a greater extent in C. quitensis. Non-structural carbohydrates were related with respiration in C. quitensis but not in D. antarctica, suggesting that respiration in the former species is likely controlled by total soluble sugars and starch during day and night, respectively. Finally, foliar carbon balance was differentially improved under warming conditions in Antarctic plants by different mechanisms, with C. quitensis deploying respiratory acclimation, while D. antarctica increased its Asat.

The effects of methanesulfonic acid on seed germination and morphophysiological changes in the seedlings of two Colobanthus species

The effect of methanesulfonic acid (MSA) on the morphophysiology and biochemistry of the subantarctic species <em>Colobanthus apetalus</em> and the Antarctic species <em>Colobanthus quitensis</em> was examined. We evaluated the effects of various concentrations of MSA on the germination capacity and germination rate of seeds, seedling growth, chlorophyll fluorescence in cotyledons, and the proline content of seedlings under laboratory conditions at temperatures of 20°C (day) and 10°C (night) with a 12/12 h photoperiod. The examined <em>C. apetalus</em> seeds were grown in a greenhouse, and <em>C. quitensis</em> seeds were harvested in Antarctica and grown in a greenhouse (Olsztyn, Poland). The seeds of <em>C. apetalus</em> were characterized by the highest germination capacity and the highest germination rate, whereas <em>C. quitensis</em> seedlings were characterized by the most favorable growth and development. Only the highest concentrations of MSA decreased the intensity of chlorophyll fluorescence in the cotyledons of both <em>Colobanthus</em> species. The proline content of <em>C. apetalus</em> and <em>C. quitensis</em> seedlings increased significantly after MSA treatments. The results of this study clearly indicated that <em>Colobanthus quitensis</em> is more resistant to chemical stress induced by MSA. This is a first study to investigate the influence of MSA on the morphophysiology and biochemistry of higher plants.

UV-B shock induces photoprotective flavonoids but not antioxidant activity in Antarctic Colobanthus quitensis (Kunth) Bartl

Colobanthus quitensis, the only dicot that inhabits Antarctica, is subjected to different abiotic factors such as high UV-B levels in spring-summer. Several authors described the flavonoid biosynthesis as crucial to tolerating UV-B enriched environments. The goal of this work is the study of the relationship between biosynthesis of flavonoids, resistance to high UV-B levels and the maintenance of redox homeostasis. With this objective, C. quitensis plantlets were subjected to low, medium and high levels of UV-B radiation, in the presence and absence of aminooxiacetic acid (AOA), a phenylalanine ammonia-lyase (PAL) inhibitor with the aim to determine the role of flavonoids in the capacity of C. quitensis to survive to UV-B. The results showed that plants subjected to increasing levels of UV-B, in the absence of the inhibitor, did not present oxidative damage; on the other hand, plants that were treated by the inhibitor showed oxidative stress symptoms and photosynthetical damage. Oxidative damage was correlated with flavonoids content; at the molecular level, these results showed an increase in transcript levels related to the phenylpropanoid pathway enzymes and their activity, as well as the expression of the UVR8−COP1-HY5 transduction system. Moreover, in AOA treated plants, the results show significant damage and plant death. Our results suggest that the survival mechanism showed by C. quitensis to UV-B radiation is mediated by biosynthesis of flavonoids.

Taxonomy and richness of yeasts associated with angiosperms, bryophytes, and meltwater biofilms collected in the Antarctic Peninsula.

The interest in the diversity of yeasts in the Antarctic environment has increased in recent years, mainly because Antarctic microbiology is a recent science, and little is known about the biodiversity and genetic resources of the microorganisms that inhabit this ecosystem. This study aimed to determine the diversity of epiphytic yeasts in samples of Deschampsia antarctica, Colobanthus quitensis, and bryophytes, as well yeasts present in biofilms collected from Antarctic meltwater. Samples were collected in the summer of 2014 and 2015 during expeditions organized by the Brazilian Antarctic Program. A total of 310 yeasts were isolated, and 34 species were identified by sequencing the D1/D2 domains of the rDNA region belonging to 18 genera. The species Vishniacozyma victoriae and Mrakia gelida were the most abundant. Dioszegia antarctica and Leucosporidium creatinivorum were found only in plant substrates. Most psychrophilic yeasts were isolated from biofilms, including Glaciozyma antarctica, Glaciozyma martinii, Mrakia gelida, Mrakia frigida, Mrakia robertii, Phenoliferia glacialis, and Phenoliferia psychrophenolica, suggesting that the substrates examined in this study represented an interesting habitat for the isolation and characterization of epiphytic and non-epiphytic yeasts that colonize the Antarctic region.

Warmer Temperatures Affect the in situ Freezing Resistance of the Antarctic Vascular Plants.

Although positive effects on growth and reproduction of Antarctic vascular plants have been reported under warmer temperatures, it could also increase the vulnerability of these plants to freezing. Thus, we assessed in situ whether warming decreases the freezing resistance of Colobanthus quitensis and Deschampsia antarctica, and we compared the level and mechanism of freezing resistance of these species in the field with previous reports conducted in lab conditions. We assessed the freezing resistance of C. quitensis and D. antarctica by determining their low temperature damage (LT50), ice nucleation temperature (NT) and freezing point (FP) in three sites of the King George Island. Plants were exposed during two growing seasons to a passive increase in the air temperature (+W). +W increased by 1K the mean air temperatures, but had smaller effects on freezing temperatures. Leaf temperature of both species was on average 1.7K warmer inside +W. Overall, warming decreased the freezing resistance of Antarctic species. The LT50 increased on average 2K for C. quitensis and 2.8K for D. antarctica. In contrast, NT and FP decreased on average c. 1K in leaves of warmed plants of both species. Our results showed an averaged LT50 of -15.3°C for C. quitensis, and of -22.8°C for D. antarctica, with freezing tolerance being the freezing resistance mechanism for both species. These results were partially consistent with previous reports, and likely explanations for such discrepancies were related with methodological differences among studies. Our work is the first study reporting the level and mechanisms of freezing resistance of Antarctic vascular plants measured in situ, and we demonstrated that although both plant species exhibited a great ability to cope with freezing temperatures during the growing season, their vulnerability to suffer freezing damage under a warming scenario increase although the magnitude of this response varied across sites and species. Hence, freezing damage should be considered when predicting changes in plant responses of C. quitensis and D. antarctica under future climate conditions of the Antarctic Peninsula.

Mesophyll conductance to CO2 is the most significant limitation to photosynthesis at different temperatures and water availabilities in Antarctic vascular species

The impact of climate change on Antarctic plants is not only associated to the effect of increased temperature but also strongly modulated by water availability (WA) illustrating the importance of this factor in predicting responses to warming. The aim of this study was to evaluate the effect of temperature and WA on the photosynthetic performance and photosynthetic limitations of the only two Antarctic vascular species: Deschampsia antarctica and Colobanthus quitensis. We hypothesize that: the ability of Antarctic plants to increase their net CO2 assimilation (AN) in response to raising growth temperature would be constrained by mesophyll conductance (gm); and decreases in water availability may counteract any benefit in carbon gain obtained upon increasing temperature. To address this issue, both species were grown (Tg) and measured (Tm) at three different temperatures (5, 10 and 16 °C). Furthermore, two different irrigation conditions (well-watered, WW, and water-deficit, WD) were applied at 16 °C. Gas-exchange measurements showed that AN and their underlying diffusive (gs and gm) and biochemical components (Vcmax) were mainly determined by Tg and, to a lesser extent by Tm. Warmer conditions favor AN of both species, although D. antarctica requires higher increases of temperature to show the same response. Changes in AN in response to either temperature or WA are due to proportional concomitant changes of stomatal and mesophyll conductances, and carboxylation capacity. However, gm remains the most important limitation at any environmental condition. Reduced WA can completely counteract any benefit to photosynthesis induced by raising temperature, suggesting that these species may present a quite homeostatic photosynthetic response to the climate changes predicted for the Antarctic region.

Range-wide pattern of genetic variation in Colobanthus quitensis

There is only one species representing Magnoliopsida which is considered as native to the Antarctic, i.e., Antarctic pearlwort (Colobanthus quitensis). Although it was intensively studied toward the morphophysiological adaptation to extreme environmental conditions of that area, there is still a lack of sufficient data on its genetic variability. Nine C. quitensis populations from Chile and the Maritime Antarctic were sampled to estimate the pattern of genetic variation in relation to the geographic distribution of analyzed populations and postglacial history of the species. The retrotransposon-based DNA marker system used in our studies appeared to be effective in revealing genetic polymorphism between individuals and genetic differentiation among populations. Although the level of polymorphism was low (9.57%), the Analysis of Molecular Variance showed that overall population differentiation was high (FST = 0.6241) and revealed significant differentiation between the Northern and Southern Group of populations as well as the population from Conguillio Park. The observed genetic subdivision of C. quitensis populations was confirmed by Bayesian clustering and results of Principal Coordinates Analysis. The Southern Group of populations was characterized by generally higher genetic diversity, which was expressed by the values of the effective number of alleles, expected heterozygosity and by the distribution of private alleles. Our results suggest that the species may have survived the Last Glacial Maximum in refugia located both on the South American continent and in geographically isolated islands of the Maritime Antarctic, i.e., they support the concept of the multiregional origin of C. quitensis in Antarctica.

Comparative transcriptome analysis of field- and chamber-grown samples of Colobanthus quitensis (Kunth) Bartl, an Antarctic flowering plant

Colobanthus quitensis is one of the two vascular plants inhabiting the Antarctic. In natural habitats, it grows in the form of a cushion or mats, commonly observed in high latitudes or alpine vegetation. Although this species has been investigated over many years to study its geographical distribution and physiological adaptations to climate change, very limited genetic information is available. The high-throughput sequencing with a de novo assembly analysis yielded 47,070 contigs with blast-hits. Through the functional classification and enrichment analysis, we identified that photosynthesis and phenylpropanoid pathway genes show differential expression depending on the habitat environment. We found that the known ‘plant core environmental stress response (PCESR)’ genes were abundantly expressed in Antarctic samples, and confirmed that their expression is mainly induced by low-temperature. In addition, we suggest that differential expression of thermomorphogenesis-related genes may contribute to phenotypic plasticity of the plant, for instance, displaying a cushion-like phenotype to adapt to harsh environments.

Hormonal and physiological changes driven by fungal endophytes increase Antarctic plant performance under UV-B radiation

Abstract Antarctic environments are amongst the most stressful habitats for life on Earth, with high intensities of solar UV-B radiation reaching the land surface. In this study, we evaluated how the photochemical efficiency, cell damage and reproductive biomass of Antarctic pearlwort (Colobanthus quitensis) were affected by different intensities of UV-B radiation in the absence and presence of fungal endophytes. In addition, we evaluated the hormonal content of plants at different UV-B radiation intensities and how hormonal content was affected by endophytes. Overall, plants exposed to UV-B radiation showed higher numbers of flowers, higher total biomass and lower lipid peroxidation in the presence of endophytes compared with plants without endophytes. Photochemical efficiency was unaffected. Fungal endophytes affected the content of salicylic acid, jasmonate, indole-3-acetate and abscisic acid in shoot tissue of plants exposed to UV-B radiation. These results suggest that endophytes could modulate the hormonal content of C. quitensis to improve its ecophysiological performance under high UV-B radiation.

The complete chloroplast genome of Colobanthus apetalus (Labill.) Druce: genome organization and comparison with related species.

Colobanthus apetalus is a member of the genus Colobanthus, one of the 86 genera of the large family Caryophyllaceae which groups annual and perennial herbs (rarely shrubs) that are widely distributed around the globe, mainly in the Holarctic. The genus Colobanthus consists of 25 species, including Colobanthus quitensis, an extremophile plant native to the maritime Antarctic. Complete chloroplast (cp) genomes are useful for phylogenetic studies and species identification. In this study, next-generation sequencing (NGS) was used to identify the cp genome of C. apetalus. The complete cp genome of C. apetalus has the length of 151,228 bp, 36.65% GC content, and a quadripartite structure with a large single copy (LSC) of 83,380 bp and a small single copy (SSC) of 17,206 bp separated by inverted repeats (IRs) of 25,321 bp. The cp genome contains 131 genes, including 112 unique genes and 19 genes which are duplicated in the IRs. The group of 112 unique genes features 73 protein-coding genes, 30 tRNA genes, four rRNA genes and five conserved chloroplast open reading frames (ORFs). A total of 12 forward repeats, 10 palindromic repeats, five reverse repeats and three complementary repeats were detected. In addition, a simple sequence repeat (SSR) analysis revealed 41 (mono-, di-, tri-, tetra-, penta- and hexanucleotide) SSRs, most of which were AT-rich. A detailed comparison of C. apetalus and C. quitensis cp genomes revealed identical gene content and order. A phylogenetic tree was built based on the sequences of 76 protein-coding genes that are shared by the eleven sequenced representatives of Caryophyllaceae and C. apetalus, and it revealed that C. apetalus and C. quitensis form a clade that is closely related to Silene species and Agrostemma githago. Moreover, the genus Silene appeared as a polymorphic taxon. The results of this study expand our knowledge about the evolution and molecular biology of Caryophyllaceae.

Antarctic rhizobacteria improve salt tolerance and physiological performance of the Antarctic vascular plants

The two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, are mostly restricted to coastal habitats where they are often exposed to sea spray with high levels of salinity. Most of the studies regarding the ability of C. quitensis and D. antarctica to cope with abiotic stress have been focused on their physiological adaptations to tolerate cold stress, but little is known about their tolerance to salinity. We investigated whether rhizospheric bacteria associated to D. antarctica and C. quitensis improve the ability of Antarctic plants to tolerate salt stress. Salt tolerance was assayed in rhizospheric bacteria, and also their effects on the ecophysiological performance (photochemical efficiency of PSII, growth, and survival) of both plants were assessed under salt stress. A total of eight bacterial rhizospheric strains capable of growing at 4 °C were isolated. The strains isolated from D. antarctica showed higher levels of salt tolerance than those strains isolated from C. quitensis. The ecophysiological performance of C. quitensis and D. antarctica was significantly increased when plants were inoculated with rhizospheric bacteria. Our results suggest that rhizospheric bacteria improve the ability of both plants to tolerate salinity stress with positive effects on the adaptation and survival of vascular plants to current conditions in Antarctic ecosystem.

In situ warming in the Antarctic: effects on growth and photosynthesis in Antarctic vascular plants.

The Antarctic Peninsula has experienced a rapid warming in the last decades. Although recent climatic evidence supports a new tendency towards stabilization of temperatures, the impacts on the biosphere, and specifically on Antarctic plant species, remain unclear. We evaluated the insitu warming effects on photosynthesis, including the underlying diffusive, biochemical and anatomical determinants, and the relative growth of two Antarctic vascular species, Colobanthus quitensis and Deschampsia antarctica, using open top chambers (OTCs) and gas exchange measurements in the field. In C.quitensis, the photosynthetic response to warming relied on specific adjustments in the anatomical determinants of the leaf CO2 transfer, which enhanced mesophyll conductance and photosynthetic assimilation, thereby promoting higher leaf carbon gain and plant growth. These changes were accompanied by alterations in the leaf chemical composition. By contrast, D.antarctica showed no response to warming, with a lack of significant differences between plants grown inside OTCs and plants grown in the open field. Overall, the present results are the first reporting a contrasting effect of insitu warming on photosynthesis and its underlying determinants, of the two unique Antarctic vascular plant species, which could have direct consequences on their ecological success under future climate conditions.

The importance of facilitative interactions on the performance of Colobanthus quitensis in an Antarctic tundra

AbstractAimsThe sign of interactions among plants in very harsh environments is under debate. The Antarctic tundra is one of the harshest environments on Earth and only two vascular plants (Deschampsia antarctica and Colobanthus quitensis) have successfully established natural populations. D. antarctica mostly establishes facilitative interactions with other species (mosses), but there is no information about the inter‐specific interactions established by C. quitensis. We assessed whether C. quitensis grows frequently associated with D. antarctica, and if D. antarctica neighbours have a positive effect on the survival, growth and photochemical efficiency of C. quitensis individuals.LocationKing George Island, Antarctic Peninsula.MethodsTo assess the spatial association among the two Antarctic vascular plants fifty 50 m × 50 cm quadrats were sampled on each of four different substrates: moss carpet areas; dead moss carpet areas dominated by D. antarctica; a transition zone between dead moss carpets and fellfields; and fellfields characterized by very poor vegetation cover. Infrared thermal images were taken to estimate whether growth associated with D. antarctica affected the foliar temperature of C. quitensis. The importance of D. antarctica neighbours on the growth, survival and photochemical efficiency of C. quitensis was evaluated with a neighbour removal experiment.ResultsThe number of C. quitensis individuals associated with D. antarctica was significantly higher than when growing alone in the moss carpet and the dead moss carpet, while in the transition zone there was a trend in that direction. C. quitensis individuals growing associated with D. antarctica were bigger than those growing alone in these three substrate types. In the fellfield site there were no significant differences, neither in the number nor the size of individuals when growing alone or associated with D. antarctica. Foliar temperature of C. quitensis individuals associated with D. antarctica was slightly (1.1°C) but significantly higher than in those growing alone. The growth, survival and photochemical efficiency of C. quitensis individuals with neighbours were higher than in individuals with neighbours removed.ConclusionsOur results indicate that D. antarctica has a facilitative effect on the growth, survival and photochemical efficiency of C. quitensis. Thus, facilitative interactions are present and are important in one of the harshest environments on Earth, although results from the fellfield site indicate that further research is needed.

Competition between native Antarctic vascular plants and invasive Poa annua changes with temperature and soil nitrogen availability

Over the last decades human have introduced non-native organisms to Antarctica, including the grass species Poa annua. This non-native grass under constant growth temperatures has been shown negatively affect the growth of the only two native Antarctic vascular plants, Deschampsia antarctica and Colobanthus quitensis, under constant growth temperatures. However, whether there are changes in the interaction between these species under warmer conditions is an important question. In cold ecosystems, soil nutrient status directly affects plant responses to increases in temperature and Antarctic soils are highly variable in nutrient supply. Thus, in this study we experimentally assessed the interaction between the non-native Poa with the two native Antarctic vascular plant species at two different temperatures and levels of nutrient availability. Individual mats of the study species were collected in King George Island, and then transported to Concepcion where we conducted competition experiments. In the first experiment we used soil similar to that of Antarctica and plants in competition were grown at two temperatures: 5°/2° and 11°/5 °C (day/night temperature). In a second experiment plants were grown in these two temperature regimes, but we varied nitrogen (N) availability by irrigating plants with Hoagland solutions that contained 8000 or 300 µM of N. Overall, Poa exerted a competitive effect on Deschampsia but only at the higher temperature and higher N availability. At 5°/11 °C the competitive response of Deschampsia to Poa was of similar magnitude to the competitive effect of P. Deschampsia, and the competitive effect was greater with at low N. The competitive effect of Poa was similar to the competitive response of Colobanthus to Poa at both temperatures and N levels. Thus, at low temperatures and N soil content the native Antarctic species might withstand Poa invasion, but this might change with climate warming.

Asymmetric responses to simulated global warming by populations of Colobanthus quitensis along a latitudinal gradient.

The increase in temperature as consequence of the recent global warming has been reported to generate new ice-free areas in the Antarctic continent, facilitating the colonization and spread of plant populations. Consequently, Antarctic vascular plants have been observed extending their southern distribution. But as the environmental conditions toward southern localities become progressively more departed from the species’ physiological optimum, the ecophysiological responses and survival to the expected global warming could be reduced. However, if processes of local adaptation are the main cause of the observed southern expansion, those populations could appear constrained to respond positively to the expected global warming. Using individuals from the southern tip of South America, the South Shetland Islands and the Antarctic Peninsula, we assess with a long term experiment (three years) under controlled conditions if the responsiveness of Colobanthus quitensis populations to the expected global warming, is related with their different foliar traits and photoprotective mechanisms along the latitudinal gradient. In addition, we tested if the release of the stress condition by the global warming in these cold environments increases the ecophysiological performance. For this, we describe the latitudinal pattern of net photosynthetic capacity, biomass accumulation, and number of flowers under current and future temperatures respective to each site of origin after three growing seasons. Overall, was found a clinal trend was found in the foliar traits and photoprotective mechanisms in the evaluated C. quitensis populations. On the other hand, an asymmetric response to warming was observed for southern populations in all ecophysiological traits evaluated, suggesting that low temperature is limiting the performance of C. quitensis populations. Our results suggest that under a global warming scenario, plant populations that inhabiting cold zones at high latitudes could increase in their ecophysiological performance, enhancing the size of populations or their spread.

Erratum to: Phenotypic variability and genetic differentiation in continental and island populations of Colobanthus quitensis (Caryophyllaceae: Antarctic pearlwort)

Erratum to: Phenotypic variability and genetic differentiation in continental and island populations of Colobanthus quitensis (Caryophyllaceae: Antarctic pearlwort)

Phenotypic variability and genetic differentiation in continental and island populations of Colobanthus quitensis (Caryophyllaceae: Antarctic pearlwort)

Colobanthus quitensis (Antarctic pearlwort) is one of the only two native vascular plants to inhabit the extreme environmental conditions of Antarctica. Colobanthus quitensis has a wide geographic distribution, both in latitude and altitude, and always inhabits extreme environments. This makes it crucial for understanding environmental tolerance mechanisms, and a useful model for studies regarding genetic diversity and intraspecific morphology. Several morphological and molecular descriptors were applied to C. quitensis populations, constituting the first study of its kind in these species. We postulated that morphological variability is strongly linked to geographic distribution, and that this is manifested in external morphological characteristics and genetic structure. A large intra- and interpopulational morphological variability was verified. Both morphological variability and genetics made it possible to form two separate groups between continental and Antarctic island populations. The genetic diversity was high to moderate with the least amount of diversity towards the north. The genetic structure was high, and the gene flow between populations was low. The correlation between morphological, genetic, geographic and altitudinal distances permits the proposal of an isolation by distance model that can be used between populations with high Bio-geographical influence. Understanding what factors lead to local or colonization adaptation, and determining the morphological variations and genetic differentiation in populations of C. quitensis, is vital for the understanding of the evolutionary history that has contributed to the success of the establishment of this species in an environment as extreme as Antarctica. Additionally, this study demonstrates the usefulness of the combined use of morpho-physiological and molecular markers for variability and diversity studies.