scholarly journals Study of Ecophysiological Responses of the Antarctic Fruticose Lichen Cladonia borealis Using the PAM Fluorescence System under Natural and Laboratory Conditions

Plants ◽  
2020 ◽  
Vol 9 (1) ◽  
pp. 85 ◽  
Author(s):  
Sung Cho ◽  
Hyoungseok Lee ◽  
Soon Hong ◽  
Jungeun Lee
Keyword(s):  
Climate Change ◽  
Amplicon Sequencing ◽  
Photosynthetic Performance ◽  
Antarctic Region ◽  
Laboratory Conditions ◽  
Psii Photochemistry ◽  
Pam Fluorescence ◽  
Ecophysiological Responses ◽  
Fruticose Lichen ◽  
The Antarctic

Antarctic lichens have been used as indicators of climate change for decades, but only a few species have been studied. We assessed the photosynthetic performance of the fruticose lichen Cladonia borealis under natural and laboratory conditions using the PAM fluorescence system. Compared to that of sun-adapted Usnea sp., the photosynthetic performance of C. borealis exhibits shade-adapted lichen features, and its chlorophyll fluorescence does not occur during dry days without rain. To understand its desiccation-rehydration responses, we measured changes in the PSII photochemistry in C. borealis under the average light intensity of dawn light and daylight and the desiccating conditions of its natural microclimate. Interestingly, samples under daylight and rapid-desiccation conditions showed a delayed reduction in Fv’/Fm’ and rETRmax, and an increase in Y(II) and Y(NPQ) levels. These results suggest that the photoprotective mechanism of C. borealis depends on sunlight and becomes more efficient with improved desiccation tolerance. Amplicon sequencing revealed that the major photobiont of C. borealis was Asterochloris irregularis, which has not been reported in Antarctica before. Collectively, these results from both field and laboratory could provide a better understanding of specific ecophysiological responses of shade-adapted lichens in the Antarctic region.

scholarly journals Seasonal ecophysiological responses and behavior of phillyrea latifoliaspecie to climate change in Tunisia

2020 ◽  
Author(s):  
Khaoula Nefzi ◽  
Baraket Mokhtar ◽  
Maroua Herzi ◽  
Zouhair Nasr
Keyword(s):  
Climate Change ◽  
Hydraulic Conductivity ◽  
Stomatal Conductance ◽  
Photochemical Efficiency ◽  
Arid Ecosystems ◽  
Maximum Efficiency ◽  
Spring Season ◽  
Phillyrea Latifolia ◽  
Psii Photochemistry ◽  
Ecophysiological Responses

Abstract Background As part of global climate change, variation in precipitation in arid ecosystems is leading to plant adaptation in water-use strategies; significant interspecific differences in ecophysiological response will change the plant behavior. The mainaim of this study was to investigate the ecophysiological responses of Phillyrea latifolia species to seasonal drought stress. Measurements were conducted between March and December 2018. The parameters studied were the Leaf Water Potential (ψ leaf ), Net photosynthesis (Pn), stomatal conductance (gs) and leaf transpiration (Tr), maximum efficiency of PSII photochemistry (Fv/ Fm), and Hydraulic conductivity. Main results The results showed that all measured parameters varied significantly with the season(P <.0001). The results of ψ leaf showed the highest average in summer (−2.99±0.08 MPa). Likewise, the highest values of the maximal photochemical efficiency of PSII (Fv/Fm) were observed in summer (0.83±0.06). However, the highest values of Pn (3.62±0.41 µmol m -2 s -1 )and Tr (0.3±0.028 µmol m -2 s -1 ) were noted in autumn. The Initial Hydraulic Conductivity ( K in ) value was in spring (1.34 -04 ±110 -5 mmol s -1 m -2 MPa -1 ) and autumn (1.1810 -04 ±2.3010 -6 mmol s -1 m -2 MPa -1 ) and the Maximal Hydraulic Conductivity ( K max ) was the highest during the spring season (3.4510 -04 ±2.7010 -11 mmol s -1 m -2 MPa -1 ). The results of the Stomatal Conductance (gs)were showed that the lowest values were recorded in summer (0.19±0.04 MPa). The percentage of loss conductivity (PLC) reached 66%. During the spring season, the soil had a decreasing moisture profile as it moved to the depths and varied from 15.23±5.48% at 20cm to 6.26±2.46% at 80 cm. Conclusions The best physiological performances of Phillyrea latifolia reported in spring and autumn may be attributed to favorable environmental conditions. The answers depend not only on the specie but also on the climates in which they grow.

scholarly journals Glacier ice archives nearly 15,000-year-old microbes and phages

Microbiome ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Zhi-Ping Zhong ◽  
Funing Tian ◽  
Simon Roux ◽  
M. Consuelo Gazitúa ◽  
Natalie E. Solonenko ◽  
...  
Keyword(s):  
Climate Change ◽  
Ice Core ◽  
Ice Cores ◽  
Single Species ◽  
Amplicon Sequencing ◽  
Future Climate Change ◽  
Climate Conditions ◽  
Glacier Ice ◽  
Sampling Procedures ◽  
Functional Genome

Abstract Background Glacier ice archives information, including microbiology, that helps reveal paleoclimate histories and predict future climate change. Though glacier-ice microbes are studied using culture or amplicon approaches, more challenging metagenomic approaches, which provide access to functional, genome-resolved information and viruses, are under-utilized, partly due to low biomass and potential contamination. Results We expand existing clean sampling procedures using controlled artificial ice-core experiments and adapted previously established low-biomass metagenomic approaches to study glacier-ice viruses. Controlled sampling experiments drastically reduced mock contaminants including bacteria, viruses, and free DNA to background levels. Amplicon sequencing from eight depths of two Tibetan Plateau ice cores revealed common glacier-ice lineages including Janthinobacterium, Polaromonas, Herminiimonas, Flavobacterium, Sphingomonas, and Methylobacterium as the dominant genera, while microbial communities were significantly different between two ice cores, associating with different climate conditions during deposition. Separately, ~355- and ~14,400-year-old ice were subject to viral enrichment and low-input quantitative sequencing, yielding genomic sequences for 33 vOTUs. These were virtually all unique to this study, representing 28 novel genera and not a single species shared with 225 environmentally diverse viromes. Further, 42.4% of the vOTUs were identifiable temperate, which is significantly higher than that in gut, soil, and marine viromes, and indicates that temperate phages are possibly favored in glacier-ice environments before being frozen. In silico host predictions linked 18 vOTUs to co-occurring abundant bacteria (Methylobacterium, Sphingomonas, and Janthinobacterium), indicating that these phages infected ice-abundant bacterial groups before being archived. Functional genome annotation revealed four virus-encoded auxiliary metabolic genes, particularly two motility genes suggest viruses potentially facilitate nutrient acquisition for their hosts. Finally, given their possible importance to methane cycling in ice, we focused on Methylobacterium viruses by contextualizing our ice-observed viruses against 123 viromes and prophages extracted from 131 Methylobacterium genomes, revealing that the archived viruses might originate from soil or plants. Conclusions Together, these efforts further microbial and viral sampling procedures for glacier ice and provide a first window into viral communities and functions in ancient glacier environments. Such methods and datasets can potentially enable researchers to contextualize new discoveries and begin to incorporate glacier-ice microbes and their viruses relative to past and present climate change in geographically diverse regions globally.

Perfluorinated compounds in the Antarctic region: Ocean circulation provides prolonged protection from distant sources

2010 ◽  
Vol 158 (9) ◽  
pp. 2985-2991 ◽  
Author(s):  
Susan Bengtson Nash ◽  
Stephen R. Rintoul ◽  
So Kawaguchi ◽  
Iain Staniland ◽  
John van den Hoff ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Perfluorinated Compounds ◽  
Antarctic Region ◽  
The Antarctic

scholarly journals Global biogeographic patterns in bipolar moss species

2017 ◽  
Vol 4 (7) ◽  
pp. 170147 ◽  
Author(s):  
E. M. Biersma ◽  
J. A. Jackson ◽  
J. Hyvönen ◽  
S. Koskinen ◽  
K. Linse ◽  
...  
Keyword(s):  
Large Scale ◽  
Common Species ◽  
Long Distance Dispersal ◽  
Stepping Stones ◽  
Long Distance ◽  
Antarctic Region ◽  
Moss Species ◽  
Biogeographic Patterns ◽  
Biogeographic Pattern ◽  
The Antarctic

A bipolar disjunction is an extreme, yet common, biogeographic pattern in non-vascular plants, yet its underlying mechanisms (vicariance or long-distance dispersal), origin and timing remain poorly understood. Here, combining a large-scale population dataset and multiple dating analyses, we examine the biogeography of four bipolar Polytrichales mosses, common to the Holarctic (temperate and polar Northern Hemisphere regions) and the Antarctic region (Antarctic, sub-Antarctic, southern South America) and other Southern Hemisphere (SH) regions. Our data reveal contrasting patterns, for three species were of Holarctic origin, with subsequent dispersal to the SH, while one, currently a particularly common species in the Holarctic ( Polytrichum juniperinum ), diversified in the Antarctic region and from here colonized both the Holarctic and other SH regions. Our findings suggest long-distance dispersal as the driver of bipolar disjunctions. We find such inter-hemispheric dispersals are rare, occurring on multi-million-year timescales. High-altitude tropical populations did not act as trans-equatorial ‘stepping-stones’, but rather were derived from later dispersal events. All arrivals to the Antarctic region occurred well before the Last Glacial Maximum and previous glaciations, suggesting that, despite the harsh climate during these past glacial maxima, plants have had a much longer presence in this southern region than previously thought.

scholarly journals Investigation of Changes of the Kinematic Parameters of Antarctic Tectonic Plate Using Data Observations of Permanent GNSS Stations

2017 ◽  
Vol 103 (1) ◽  
pp. 119-135 ◽  
Author(s):  
Kornylii Tretyak ◽  
Al-Alusi Forat ◽  
Yurii Holubinka
Keyword(s):  
Angular Velocity ◽  
Kinematic Parameters ◽  
Antarctic Region ◽  
Tectonic Plate ◽  
Euler Pole ◽  
The Mean ◽  
Using Data ◽  
Gnss Permanent Stations ◽  
The Antarctic

Abstract The paper describes a modified algorithm of determination of the Euler pole coordinates and angular velocity of the tectonic plate, considering the continuous and uneven distribution of daily measurements of GNSS permanent stations. Using developed algorithm were determined the mean position of Euler pole and angular velocity of Antarctic tectonic plate and their annual changes. As the input data, we used the results of observations, collected on 28 permanent stations of the Antarctic region, within the period from 1996 to 2014.

scholarly journals Introduction. Antarctic ecology: from genes to ecosystems. Part 2. Evolution, diversity and functional ecology

2007 ◽  
Vol 362 (1488) ◽  
pp. 2187-2189 ◽  
Author(s):  
Alex D Rogers ◽  
Eugene J Murphy ◽  
Nadine M Johnston ◽  
Andrew Clarke
Keyword(s):  
Climate Change ◽  
Life Histories ◽  
Natural Populations ◽  
Environmental Parameters ◽  
Functional Ecology ◽  
Antarctic Species ◽  
Trade Offs ◽  
Genes To Ecosystems ◽  
Micro Organisms ◽  
The Antarctic

The Antarctic biota has evolved over the last 100 million years in increasingly isolated and cold conditions. As a result, Antarctic species, from micro-organisms to vertebrates, have adapted to life at extremely low temperatures, including changes in the genome, physiology and ecological traits such as life history. Coupled with cycles of glaciation that have promoted speciation in the Antarctic, this has led to a unique biota in terms of biogeography, patterns of species distribution and endemism. Specialization in the Antarctic biota has led to trade-offs in many ecologically important functions and Antarctic species may have a limited capacity to adapt to present climate change. These include the direct effects of changes in environmental parameters and indirect effects of increased competition and predation resulting from altered life histories of Antarctic species and the impacts of invasive species. Ultimately, climate change may alter the responses of Antarctic ecosystems to harvesting from humans. The unique adaptations of Antarctic species mean that they provide unique models of molecular evolution in natural populations. The simplicity of Antarctic communities, especially from terrestrial systems, makes them ideal to investigate the ecological implications of climate change, which are difficult to identify in more complex systems.

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