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SUMMARY Photosynthetic and chemosynthetic extremophiles have evolved adaptations to thrive in challenging environments by finely adjusting their metabolic pathways through evolutionary processes. A prime adaptation target to allow autotrophy in extreme conditions is the enzyme Rubisco, which plays a central role in the conversion of inorganic to organic carbon. Here, we present an extensive compilation of Rubisco kinetic traits from a wide range of species of bacteria, archaea, algae, and plants, sorted by phylogenetic group, Rubisco type, and extremophile type. Our results show that Rubisco kinetics for the few extremophile organisms reported up to date are placed at the margins of the enzyme's natural variability. Form ID Rubisco from thermoacidophile rhodophytes and form IB Rubisco from halophile terrestrial plants exhibit higher specificity and affinity for CO2 than their non‐extremophilic counterparts, as well as higher carboxylation efficiency, whereas form ID Rubisco from psychrophile organisms possess lower affinity for O2. Additionally, form IB Rubisco from thermophile cyanobacteria shows enhanced CO2 specificity when compared to form IB non‐extremophilic cyanobacteria. Overall, these findings highlight the unique characteristics of extremophile Rubisco enzymes and provide useful clues to guide next explorations aimed at finding more efficient Rubiscos. [ABSTRACT FROM AUTHOR]

Ever since the first human reached the South Pole, studies have sought to explore the impact of an isolated, confined, and unusual environment on human adaptation. The findings have highlighted both negative and salutogenic effects on crews. Although several studies have focused on adaptation in the polar regions, we still do not fully understand its mechanisms. Thus, the objectives of the present study are: (1) to investigate the impact of a one-year stay in Antarctica on health adaptation; and (2) to assess recovery from this experience two days later. Seventeen healthy participants were recruited to stay for one year at the French Dumont d'Urville station in Antarctica. Psychological, physiological, and exteroceptive measures were recorded on the day of arrival at the station (baseline), during each quarter of the wintering season (M4, M7, M10, M12), and two days after the return to the continent (D+2). Subjects were allocated to two groups according to their scores on the General Health Questionnaire at baseline, as follows: very limited or no existence of minor non-psychiatric or psychotic disorders (higher than normal, HN); and standard values for non-psychiatric or minor psychotic disorders within the general population (ordinary range, OR). Our results highlight both an adaptative response during the winter months, and pathogenic states during the last quarter of the mission and at recovery (D+2), which are still below normal values for psychological disorders and stress. The analysis of OR and HN groups during overwintering highlights a decrease in psychosensory responses, and thus poorer adaptation. Spending a year in Antarctica no longer has harmful consequences (except during the third quarter of the mission), and the harshness of the environment in midwinter does not seem to be an aggravating factor for the winterers included in this study. Nevertheless, the General Health Questionnaire indicates two levels of adaptation during the mission. The latter observation suggests that there is a need to select the most-adaptable crews to maintain high performance during overwintering, and to prepare for the return to the continent. Taken together, our results contribute to a better understanding of adaptation in extreme environments, notably future dark space exploration. • Winterovering does no longer produce harmful consequences. • Adaptation is shown during the winter peak. • A third quarter phenomenon is found near the end of the mission. • Psychological stability leads to better adaptative abilities. • The return on the continent constitutes a new phase of adaptation. [ABSTRACT FROM AUTHOR]

Natural environments vary, and organisms cope with this variation in two general ways: local adaptation and phenotypic plasticity, although these strategies often overlap and interact. This study explored how local adaptation, phenotypic plasticity, and their interactions shaped phenotypic variation in populations of Poecilia mexicana, an extremophile fish living in adjacent but ecologically divergent habitats. By comparing populations from the wild with fish raised in a common-garden environment, we evaluated how genetic differentiation between populations and plasticity contributed to the phenotypic variation observed in nature. We quantified variation in the size of six organs (brain, eyes, gills, heart, liver, and gastrointestinal tract), routine metabolic rate, and body shape. We found evidence for genetic differences between populations impacting the expression of the majority of traits, in addition to or in interaction with phenotypic plasticity and other predictor variables. Overall, our results suggest that trait divergence between populations was at least in part driven by evolutionary change and not just merely by plasticity induced by environmental differences between habitats. Future studies will have to rigorously test whether evolutionary divergence was caused by natural selection and what traits represent adaptations to the different ecological conditions. [ABSTRACT FROM AUTHOR]

Adaptation to extreme environments often involves the evolution of dramatic physiological changes. To better understand how organisms evolve these complex phenotypic changes, the repeatability and predictability of evolution, and possible constraints on adapting to an extreme environment, it is important to understand how adaptive variation has evolved. Poeciliid fishes represent a particularly fruitful study system for investigations of adaptation to extreme environments due to their repeated colonization of toxic hydrogen sulfide–rich springs across multiple species within the clade. Previous investigations have highlighted changes in the physiology and gene expression in specific species that are thought to facilitate adaptation to hydrogen sulfide–rich springs. However, the presence of adaptive nucleotide variation in coding and regulatory regions and the degree to which convergent evolution has shaped the genomic regions underpinning sulfide tolerance across taxa are unknown. By sampling across seven independent lineages in which nonsulfidic lineages have colonized and adapted to sulfide springs, we reveal signatures of shared evolutionary rate shifts across the genome. We found evidence of genes, promoters, and putative enhancer regions associated with both increased and decreased convergent evolutionary rate shifts in hydrogen sulfide–adapted lineages. Our analysis highlights convergent evolutionary rate shifts in sulfidic lineages associated with the modulation of endogenous hydrogen sulfide production and hydrogen sulfide detoxification. We also found that regions with shifted evolutionary rates in sulfide spring fishes more often exhibited convergent shifts in either the coding region or the regulatory sequence of a given gene, rather than both. [ABSTRACT FROM AUTHOR]

Extremotolerant and extremophilic fungi are an important part of microbial communities that thrive in extreme environments. Among them, the black yeasts are particularly adaptable. They use their melanized cell walls and versatile morphology, as well as a complex set of molecular adaptations, to survive in conditions that are lethal to most other species. In contrast to extremophilic bacteria and archaea, these fungi are typically extremotolerant rather than extremophilic and exhibit an unusually wide ecological amplitude. Some extremely halotolerant black yeasts can grow in near-saturated NaCl solutions, but can also grow on normal mycological media. They adapt to the low water activity caused by high salt concentrations by sensing their environment, balancing osmotic pressure by accumulating compatible solutes, removing toxic salt ions from the cell using membrane transporters, altering membrane composition and remodelling the highly melanized cell wall. As protection against extreme conditions, halotolerant black yeasts also develop different morphologies, from yeast-like to meristematic. Genomic studies of black yeasts have revealed a variety of reproductive strategies, from clonality to intense recombination and the formation of stable hybrids. Although a comprehensive understanding of the ecological role and molecular adaptations of halotolerant black yeasts remains elusive and the application of many experimental methods is challenging due to their slow growth and recalcitrant cell walls, much progress has been made in deciphering their halotolerance. Advances in molecular tools and genomics are once again accelerating the research of black yeasts, promising further insights into their survival strategies and the molecular basis of their adaptations. Key points: • Black yeasts show remarkable adaptability to environmental stress • Black yeasts are part of microbial communities in hypersaline environments • Halotolerant black yeasts utilise various molecular and morphological adaptations [ABSTRACT FROM AUTHOR]

Extreme environments on Earth are typically devoid of macro life forms and are inhabited predominantly by highly adapted and specialized microorganisms. The discovery and persistence of these extremophiles provides tools to model how life arose on Earth and inform us on the limits of life. Fungi, in particular, are among the most extreme-tolerant organisms with highly versatile lifestyles and stunning ecological and morphological plasticity. Here, we overview the most notable examples of extremophilic and stress-tolerant fungi, highlighting their key roles in the functionality and balance of extreme ecosystems. The remarkable ability of fungi to tolerate and even thrive in the most extreme environments, which preclude most organisms, have reshaped current concepts regarding the limits of life on Earth.

Introduction: Long-duration space missions will be a real challenge for maintaining astronauts' adaptability. Research on transcutaneous vagus nerve stimulation (taVNS) is expanding rapidly, and its modalities constitute a major research challenge. A growing number of reviews stress the need to validate biomarkers for monitoring effects to enhance our understanding of the processes by which taVNS acts. Heart rate variability (HRV) appears to be a relevant candidate that informs on the autonomic nervous system (ANS). This is a promising technique to minimize the pathogenic effects of such large-scale missions and thus might be a relevant countermeasure. This study aimed to investigate the impact of taVNS on cognitive, psychological, and physiological functioning, including ANS functioning, and the benefits of increasing the number of taVNS sessions. Method: A total of 44 healthy participants were randomly assigned to one of the two cross-over protocols: a single session protocol (one taVNS and one sham simulation) or a repeated session protocol (three taVNS and three sham simulations). Cognitive, psychological, and physiological measures were performed before (pre) and after (post) each intervention. Sleep monitoring was only recorded before the first and after the last intervention in each protocol. For the repeated session protocol only, participants were allocated to two groups according to their parasympathetic activation gain during the three interventions: high parasympathetic delta (HPd) and low parasympathetic delta (LPd). Results: Participants in the repeated session protocol increased their HRV, cognitive performance, and sleep efficiency. In particular, taVNS induced higher parasympathetic activation and cardiac flexibility compared to the sham simulation in the repeated session protocol. Nevertheless, the perception of stress may indicate a nocebo effect of the repeated session. The HPd profile had higher interoceptive awareness, HRV highlighted by non-linear measures, and cognitive performance, but presented a decrease in some indicators of sleep efficiency compared to the LPd profile. Conclusion: taVNS seems to induce positive health outcomes, especially when the stimulation is repeated three times per week. Our findings highlight the benefits of parasympathetic activation during taVNS on psychophysiological and cognitive functioning. Further research is needed to validate these results on a large sample, using longitudinal measures over several months. This intervention appears promising as a countermeasure to extreme missions and occupations. [ABSTRACT FROM AUTHOR]

Human habitation and adaptation to extreme environments have a deep history in anthropological research. Anthropologists' understanding of these ecological pressures and how humans respond to them has grown substantially over the last 100+ years. This review covers long-standing knowledge on adaptation to classic extreme conditions of heat, cold, and high altitude, while also updating the areas in which recent research has broadened our understanding of human adaptation, acclimatization, and resilience. Unfortunately, the intersecting stresses of structural inequality and climate change have made these extremes more extreme, with drastic negative impacts on health and well-being. Future research will need to explore how extreme environments, structural inequality, and climate change are embodied as well as mitigated so that humans are better prepared to face a rapidly changing world. [ABSTRACT FROM AUTHOR]

Data on B chromosomes in populations of different systematic groups of plants and animals from extreme habitats, i.e., the range boundaries and its parts exposed to adverse environmental factors are reviewed. Analysis showed rather similar patterns of B chromosome distribution in the species extreme habitats. In particular, a tendency to the increased polymorphism and increase in B chromosome number and frequency, which was accompanied by changes in the karyotype, as well as genomic and chromosomal abnormalities in their carriers, was observed. B chromosomes are often found in species with wide ranges. The possible adaptive role of B chromosomes in the vital activity of organisms and the genome evolution is discussed. [ABSTRACT FROM AUTHOR]

Recent colonization of extreme environments provides unique opportunities to study the early steps of adaptation and the potential for rapid convergent evolution. However, phenotypic shifts during recent colonization may also be due to plasticity in response to changes in the rearing environment. Here, we analyzed a suite of morphological and behavioral traits in paired surface, subterranean, and facultatively subterranean Mexican tetras (Astyanax mexicanus) from recent introductions in two separate watersheds outside of their native range. We found a variety of phenotypic and behavioral shifts between subterranean and surface populations that are similar to those observed in relatively ancient populations in Mexico. Despite this rapid morphological divergence, we found that most of these trait differences were due to plasticity in response to rearing environments. While most trait assays in common-garden, lab-raised fish indicated that phenotypic shifts in wild fish were the result of plasticity, we also found evidence of genetic control in several traits present in subterranean populations. Interestingly, wall following behavior, an important subterranean foraging behavior, was greater in lab-born subterranean fish than in lab-born surface fish, suggesting rapid divergence of this trait between subterranean and surface populations. Thus, this study sheds light on the early steps of subterranean evolution, identifies potential rapid behavioral evolution, and suggests that plasticity in traits involving exploratory behavior may facilitate subterranean colonization. [ABSTRACT FROM AUTHOR]

In an era of rapid climate change and expansion of desertification, the extremely harsh conditions of drylands are a true challenge for microbial life. Under drought conditions, where most life forms cannot survive, rocks represent the main refuge for life. Indeed, the endolithic habitat provides thermal buffering, physical stability, and protection against incident ultraviolet (UV) radiation and solar radiation and, to some extent, ensures water retention to microorganisms. The study of these highly specialized extreme-tolerant and extremophiles may provide tools for understanding microbial interactions and processes that allow them to keep their metabolic machinery active under conditions of dryness and oligotrophy that are typically incompatible with active life, up to the dry limits for life. Despite lithobiontic communities being studied all over the world, a comprehensive understanding of their ecology, evolution, and adaptation is still nascent. Herein, we survey the fungal component of these microbial ecosystems. We first provide an overview of the main defined groups (i.e., lichen-forming fungi, black fungi, and yeasts) of the most known and studied Antarctic endolithic communities that are almost the only life forms ensuring ecosystem functionality in the ice-free areas of the continent. For each group, we discuss their main traits and their diversity. Then, we focus on the fungal taxonomy and ecology of other worldwide endolithic communities. Finally, we highlight the utmost importance of a global rock survey in order to have a comprehensive view of the diversity, distribution, and functionality of these fungi in drylands, to obtain tools in desert area management, and as early alarm systems to climate change.

BackgroundThe deep ocean is characterized by low temperatures, high hydrostatic pressures, and low concentrations of organic matter. While these conditions likely select for distinct genomic characteristics within prokaryotes, the attributes facilitating adaptation to the deep ocean are relatively unexplored. In this study, we compared the genomes of seven strains within the genus Colwellia, including some of the most piezophilic microbes known, to identify genomic features that enable life in the deep sea.ResultsSignificant differences were found to exist between piezophilic and non-piezophilic strains of Colwellia. Piezophilic Colwellia have a more basic and hydrophobic proteome. The piezophilic abyssal and hadal isolates have more genes involved in replication/recombination/repair, cell wall/membrane biogenesis, and cell motility. The characteristics of respiration, pilus generation, and membrane fluidity adjustment vary between the strains, with operons for a nuo dehydrogenase and a tad pilus only present in the piezophiles. In contrast, the piezosensitive members are unique in having the capacity for dissimilatory nitrite and TMAO reduction. A number of genes exist only within deep-sea adapted species, such as those encoding d-alanine-d-alanine ligase for peptidoglycan formation, alanine dehydrogenase for NADH/NAD+ homeostasis, and a SAM methyltransferase for tRNA modification. Many of these piezophile-specific genes are in variable regions of the genome near genomic islands, transposases, and toxin-antitoxin systems.ConclusionsWe identified a number of adaptations that may facilitate deep-sea radiation in members of the genus Colwellia, as well as in other piezophilic bacteria. An enrichment in more basic and hydrophobic amino acids could help piezophiles stabilize and limit water intrusion into proteins as a result of high pressure. Variations in genes associated with the membrane, including those involved in unsaturated fatty acid production and respiration, indicate that membrane-based adaptations are critical for coping with high pressure. The presence of many piezophile-specific genes near genomic islands highlights that adaptation to the deep ocean may be facilitated by horizontal gene transfer through transposases or other mobile elements. Some of these genes are amenable to further study in genetically tractable piezophilic and piezotolerant deep-sea microorganisms.

Genomic analysis has shed light on how hadal snailfish have adapted to living at depths of several thousand metres.

Key message: Positive selection genes are related to metabolism, while differentially expressed genes are related to photosynthesis, suggesting that genetic adaptation and expression regulation may play independent roles in different gene classes. Genome-wide investigation of the molecular mechanisms for high-altitude adaptation is an intriguing topic in evolutionary biology. The Qinghai-Tibet Plateau (QTP) with its extremely variable environments is an ideal site for studying high-altitude adaptation. Here, we used transcriptome data of 100 individuals from 20 populations collected from various altitudes on the QTP to investigate the adaptive mechanisms of the aquatic plant Batrachium bungei at both the genetic and transcriptional level. To explore genes and biological pathways that may contribute to QTP adaptation, we employed a two-step approach, in which we identified positively selected genes and differentially expressed genes using the landscape genomic and differential expression approaches. The positive selection analysis showed that genes involved in metabolic regulation played a crucial role in B. bungei adaptation to the extreme environments of the QTP, especially intense ultraviolet radiation. Altitude-based differential expression analysis suggested that B. bungei could increase the rate of energy dissipation or reduce the efficiency of light energy absorption by down regulating the expression of photosynthesis-related genes to adapt to the strong ultraviolet radiation. Weighted gene co-expression network analysis identified ribosomal genes as hubs of altitude adaptation in B. bungei. Only a small part of genes (about 10%) overlapped between positively selected genes and differentially expressed genes in B. bungei, suggesting that genetic adaptation and gene expression regulation might play relatively independent roles in different categories of functional genes. Taken together, this study enriches our understanding of the high-altitude adaptation mechanism of B. bungei on the QTP. [ABSTRACT FROM AUTHOR]

Extreme environments test the limits of life; yet, some organisms thrive in harsh conditions. Extremophile lineages inspire questions about how organisms can tolerate physiochemical stressors and whether the repeated colonization of extreme environments is facilitated by predictable and repeatable evolutionary innovations. We identified the mechanistic basis underlying convergent evolution of tolerance to hydrogen sulfide (H2S)-a toxicant that impairs mitochondrial function-across evolutionarily independent lineages of a fish (Poecilia mexicana, Poeciliidae) from H2S-rich springs. Using comparative biochemical and physiological analyses, we found that mitochondrial function is maintained in the presence of H2S in sulfide spring P. mexicana but not ancestral lineages from nonsulfidic habitats due to convergent adaptations in the primary toxicity target and a major detoxification enzyme. Genome-wide local ancestry analyses indicated that convergent evolution of increased H2S tolerance in different populations is likely caused by a combination of selection on standing genetic variation and de novo mutations. On a macroevolutionary scale, H2S tolerance in 10 independent lineages of sulfide spring fishes across multiple genera of Poeciliidae is correlated with the convergent modification and expression changes in genes associated with H2S toxicity and detoxification. Our results demonstrate that the modification of highly conserved physiological pathways associated with essential mitochondrial processes mediates tolerance to physiochemical stress. In addition, the same pathways, genes, and-in some instances-codons are implicated in H2S adaptation in lineages that span 40 million years of evolution.

Microorganisms, in the most hyperarid deserts around the world, inhabit the inside of rocks as a survival strategy. Water is essential for life, and the ability of a rock substrate to retain water is essential for its habitability. Here we report the mechanism by which gypsum rocks from the Atacama Desert, Chile, provide water for its colonizing microorganisms. We show that the microorganisms can extract water of crystallization (i.e., structurally ordered) from the rock, inducing a phase transformation from gypsum (CaSO4·2H2O) to anhydrite (CaSO4). To investigate and validate the water extraction and phase transformation mechanisms found in the natural geological environment, we cultivated a cyanobacterium isolate on gypsum rock samples under controlled conditions. We found that the cyanobacteria attached onto high surface energy crystal planes ({011}) of gypsum samples generate a thin biofilm that induced mineral dissolution accompanied by water extraction. This process led to a phase transformation to an anhydrous calcium sulfate, anhydrite, which was formed via reprecipitation and subsequent attachment and alignment of nanocrystals. Results in this work not only shed light on how microorganisms can obtain water under severe xeric conditions but also provide insights into potential life in even more extreme environments, such as Mars, as well as offering strategies for advanced water storage methods.

Yellowhorn (Xanthoceras sorbifolia) is a species of deciduous tree that is native to Northern and Central China, including Loess Plateau. The yellowhorn tree is a hardy plant, tolerating a wide range of growing conditions, and is often grown for ornamental purposes in parks, gardens, and other landscaped areas. The seeds of yellowhorn are edible and contain rich oil and fatty acid contents, making it an ideal plant for oil production. However, the mechanism of its ability to adapt to extreme environments and the genetic basis of oil synthesis remains to be elucidated. In this study, we reported a high-quality and near gap-less yellowhorn genome assembly, containing the highest genome continuity with a contig N50 of 32.5 Mb. Comparative genomics analysis showed that 1,237 and 231 gene families under expansion and the yellowhorn-specific gene family NBARC were enriched in photosynthesis and root cap development, which may contribute to the environmental adaption and abiotic stress resistance of yellowhorn. A 3-ketoacyl-CoA thiolase (KAT) gene (Xso_LG02_00600) was identified under positive selection, which may be associated with variations of seed oil content among different yellowhorn cultivars. This study provided insights into environmental adaptation and seed oil content variations of yellowhorn to accelerate its genetic improvement. [ABSTRACT FROM AUTHOR]

Quantifying trait–environment associations can help elucidate the processes underpinning the structure of species assemblages. However, most work has focused on trait variation across rather than within species, meaning that processes operating at the intraspecific levels cannot be detected. Incorporating intraspecific trait variation in community‐wide analyses can provide valuable insights about the role of morphological adaptation and plasticity on species persistence and the composition of ecological communities.Here, we assessed geographical variation in the direction (i.e. adaptation) and strength of selection, and the magnitude of plasticity, by examining community‐wide trait variation in ant communities along an environmental gradient spanning 9° latitude in Quebec, Canada. Specifically, we measured 9 morphological traits related to foraging strategies, resource use and thermal regulation at 20 locations across temperate and boreal forests. We then examined how the mean and variance of these traits varied along temperature and precipitation gradients. Moreover, we examined how these trait–environment relationships varied across levels of organization, from individual workers (intraspecific) to colonies (intraspecific) and species (interspecific).We observed changes in mean trait values along environmental gradients, but very little change in variance. Specifically, we observed a decrease in the mean length of antennae and an increase in the mean eye length from mild (warm and wet) to more extreme environments (cold and dry). These shifts in trait means were mostly coordinated across organizational levels (i.e. worker, colony and species). We also observed a general increase in trait variance from mild to extreme environments, but only at the species level.Our findings suggest that stressful environmental conditions exert a strong selection pressure on ant morphology causing shifts in optimal trait values. These adaptations may enable persistence at the northern edge of the boreal forest and therefore influence the composition of these ant communities. Specifically, ants with large eyes and short antennae are overrepresented at the transition zone between the boreal forest and the tundra, possibly representing an adaptation to these more open habitats. Our study demonstrates that combining spatial and community‐wide intraspecific functional trait data provides a promising way forward to gain new insights on trait adaptations and processes underpinning community structure along environmental gradients. Read the free Plain Language Summary for this article on the Journal blog. [ABSTRACT FROM AUTHOR]

Climate change is increasingly exposing populations to rare and novel environmental conditions. Theory suggests that extreme conditions will expose cryptic phenotypes, with a concomitant increase in trait variation. Although some empirical support for this exists, it is also well established that physiological mechanisms (e.g. heat shock protein expression) change when organisms are exposed to constant versus fluctuating temperatures. To determine the effect of common, rare and novel temperatures on the release of hidden variation, we exposed fathead minnows, Pimephales promelas, to five fluctuating and four constant temperature regimes (constant treatments: 23.5, 25, 28.5 and 31°C; all fluctuating treatments shared a minimum temperature of 22°C at 00.00 and a maximum of 25, 28, 31, 34 or 37°C at 12.00). We measured each individuals length weekly over 60 days, critical thermal maximum (CTmax), five morphometric traits (eye anterior-posterior distance, pelvic fin length, pectoral fin length, pelvic fin ray count and pectoral fin ray count) and fluctuating asymmetry (FA, absolute difference between left and right morphometric measurements; FA is typically associated with stress). Length-at-age in both constant and fluctuating conditions decreased with temperature, and this traits variance decreased with temperature under fluctuating conditions but increased and then decreased in constant temperatures. CTmax in both treatments increased with increasing water temperature, while its variance decreased in warmer waters. No consistent pattern in mean or variance was found across morphometric traits or FA. Our results suggest that, for fathead minnows, variance can decrease in important traits (e.g. length-at-age and CTmax) as the environment becomes more stressful, so it may be difficult to establish comprehensive rules for the effects of rarer or stressful environments on trait variation. This article is part of the theme issue The role of plasticity in phenotypic adaptation to rapid environmental change.

Insights into assemblages that can persist in extreme environments are still emerging. Ocean warming and acidification select against species with low physiological tolerance (trait‐based 'filtering'). However, intraspecific trait variation can promote species adaptation and persistence, with potentially large effects on assemblage structure. By sampling nine coral traits (four morphological, four tissue and one skeletal) along an offshore–inshore gradient in temperature and pH, we show that distantly related coral species undergo consistent intraspecific changes as they cross into warm, acidic environments. Intraspecific variation and species turnover each favoured colonies with greater tissue biomass, higher symbiont densities and reduced skeletal investments, indicating strong filtering on colony physiology within and across species. Physiological tissue traits were highly variable within species and were independent of morphology, enabling morphologically diverse species to cross into sites of elevated temperature and acidity. Widespread intraspecific change can therefore counter the loss of biodiversity and morphological structure across a steep environmental gradient. [ABSTRACT FROM AUTHOR]

Camels, known as the “Ship of the Desert,” play a vital role in the ecosystems and economies of arid and semi-arid regions. They provide meat, milk, transportation, and other essential services, and their resilience to harsh environments makes them invaluable. Despite their similarities, camel breeds exhibit notable differences in size, color, and structure, with over 40 million camels worldwide. This number is projected to increase, underscoring their growing significance. Economically, camels are crucial for food production, tourism, and trade, with camel racing being particularly significant in Arab countries. Their unique physiological traits, such as low disease susceptibility and efficient water conservation, further enhance their value. Camel products, especially meat and milk, offer substantial nutritional and therapeutic benefits, contributing to their high demand. Genetic diversity studies have advanced our understanding of camels’ adaptation to extreme environments. Functional genomics and whole-genome sequencing have identified genes responsible for these adaptations, aiding breeding programs and conservation efforts. High-throughput sequencing has revealed genetic markers linked to traits like milk production and disease resistance. The development of SNP chips has revolutionized genetic studies by providing a cost-effective alternative to whole-genome sequencing. These tools facilitate large-scale genotyping, essential for conserving genetic diversity and improving breeding strategies. To prevent the depletion of camel genetic diversity, it is crucial to streamline in situ and ex situ conservation efforts to maintain their ecological and economic value. A comprehensive approach to camel conservation and genetic preservation, involving advanced genomic technologies, reproductive biotechniques, and sustainable management practices, will ensure their continued contribution to human societies. [ABSTRACT FROM AUTHOR]

The colonization of novel environments often involves changes in gene expression, protein coding sequence, or both. Studies of how populations adapt to novel conditions, however, often focus on only one of these two processes, potentially missing out on the relative importance of different parts of the evolutionary process. In this study, our objectives were 1) to better understand the qualitative concordance between conclusions drawn from analyses of differential expression and changes in genic sequence and 2) to quantitatively test whether differentially expressed genes were enriched for sites putatively under positive selection within gene regions. To achieve this, we compared populations of fish (Poecilia mexicana) that have independently adapted to hydrogen-sulfide-rich environments in southern Mexico to adjacent populations residing in nonsulfidic waters. Specifically, we used RNA-sequencing data to compare both gene expression and DNA sequence differences between populations. Analyzing these two different data types led to similar conclusions about which biochemical pathways (sulfide detoxification and cellular respiration) were involved in adaptation to sulfidic environments. Additionally, we found a greater overlap between genes putatively under selection and differentially expressed genes than expected by chance. We conclude that considering both differential expression and changes in DNA sequence led to a more comprehensive understanding of how these populations adapted to extreme environmental conditions. Our results imply that changes in both gene expression and DNA sequence-sometimes at the same loci-may be involved in adaptation.

Genome–environment Associations (GEA) or Environmental Genome-Wide Association scans (EnvGWAS) have been poorly applied for studying the genomics of adaptive traits in bread wheat landraces (Triticum aestivum L.). We analyzed 990 landraces and seven climatic variables (mean temperature, maximum temperature, precipitation, precipitation seasonality, heat index of mean temperature, heat index of maximum temperature, and drought index) in GEA using the FarmCPU approach with GAPIT. Historical temperature and precipitation values were obtained as monthly averages from 1970 to 2000. Based on 26,064 high-quality SNP loci, landraces were classified into ten subpopulations exhibiting high genetic differentiation. The GEA identified 59 SNPs and nearly 89 protein-encoding genes involved in the response processes to abiotic stress. Genes related to biosynthesis and signaling are mainly mediated by auxins, abscisic acid (ABA), ethylene (ET), salicylic acid (SA), and jasmonates (JA), which are known to operate together in modulation responses to heat stress and drought in plants. In addition, we identified some proteins associated with the response and tolerance to stress by high temperatures, water deficit, and cell wall functions. The results provide candidate regions for selection aimed to improve drought and heat tolerance in bread wheat and provide insights into the genetic mechanisms involved in adaptation to extreme environments. [ABSTRACT FROM AUTHOR]

Seasonal variation in extreme environments is a threat to endangered species. The gut microbiota is important in the adaptive strategies of wild herbivores, and herbivores will contact the soil microbiota when they are feeding. However, there are no studies about the effects of soil microbiota on the gut microbiota of wild herbivores. Understanding the seasonal adaptive strategies of wild herbivores based on their gut microbiota and the effects of soil microbiota on the herbivorous gut microbiota is indispensable for making optimal conservation recommendations. To address those issues, we compared the diversity and functions of gut microbiota in goitered gazelles between winter and summer with a non-invasive fecal sampling method from the Qaidam Basin based on 16S rRNA V3–V4 regions. The data showed that seasonal variations caused the significant changes in gut microbiota at α-and β-diversity levels. The main gut microbial function was “Metabolism”. It showed significant seasonal changes. The goitered gazelles adapted to the seasonal changes by increasing the relative abundance of Firmicutes, Christensenellaceae, Bacteroides and the function about “Metabolism” in the winter to improve the adaptability. We also compared the effects of soil microbiota on the gut microbiota between winter and summer, covering source tracking analysis and the seasonal differences in ecological assembly processes. The contribution of soil microbiota on the gut microbiota of goitered gazelles was 5.3095% and 15.6347% in winter and summer, respectively, which was greater than on species of animals living underground. Seasonal variation also influenced the ecological processes of microbiota both in the gut and soil. Due to the differences in environments, the ecological processes between fecal microbiota and soil microbiota showed significant differences, and they were dominated by stochastic processes and deterministic processes, respectively. The soil microbiota has contributed to the gut microbiota, but not a decisive factor. Our research laid the foundation on the seasonal and soil microbiota effects on the adaptive strategies of goitered gazelles, and is the first study to explain the soil microbiota influence on the gut microbiota of wild herbivores. [ABSTRACT FROM AUTHOR]

Summary: Current crop yield of the best ideotypes is stagnating and threatened by climate change. In this scenario, understanding wild plant adaptations in extreme ecosystems offers an opportunity to learn about new mechanisms for resilience. Previous studies have shown species specificity for metabolites involved in plant adaptation to harsh environments.Here, we combined multispecies ecological metabolomics and machine learning‐based generalized linear model predictions to link the metabolome to the plant environment in a set of 24 species belonging to 14 families growing along an altitudinal gradient in the Atacama Desert.Thirty‐nine common compounds predicted the plant environment with 79% accuracy, thus establishing the plant metabolome as an excellent integrative predictor of environmental fluctuations. These metabolites were independent of the species and validated both statistically and biologically using an independent dataset from a different sampling year. Thereafter, using multiblock predictive regressions, metabolites were linked to climatic and edaphic stressors such as freezing temperature, water deficit and high solar irradiance.These findings indicate that plants from different evolutionary trajectories use a generic metabolic toolkit to face extreme environments. These core metabolites, also present in agronomic species, provide a unique metabolic goldmine for improving crop performances under abiotic pressure. [ABSTRACT FROM AUTHOR]

The stoichiometric characteristics of plant nitrogen (N) and phosphorus (P) and their correlations with soil properties are regarded as key for exploring plant physiological and ecological processes and predicting ecosystem functions. However, quantitative studies on the relative contributions of water–salt gradients and nutrient gradients to plant stoichiometry are limited. In addition, previous studies have been conducted at the plant species and individual levels, meaning that how community-scale stoichiometry responds to soil properties is still unclear. Therefore, we selected typical sample strips from 13 sampling sites in arid regions to assess the leaf N and P levels of 23 species of desert plants and measure the corresponding soil water content, total salt content, total nitrogen content, and total phosphorus content. The aim was to elucidate the main soil properties that influence the stoichiometric characteristics of desert plants and compare the individual and community responses to those soil properties. Our results indicated that the growth of desert plants is mainly limited by nitrogen, with individual plant leaf nitrogen and phosphorus concentrations ranging from 4.08 to 31.39 mg g−1 and 0.48 to 3.78 mg g−1, respectively. Community stoichiometry was significantly lower than that of individual plants. A significant correlation was observed between the mean N concentration, P concentration, and N:P ratio of plant leaves. At the individual plant scale, aridity significantly reduced leaf N and P concentrations, while high salt content significantly increased leaf N concentrations. At the community scale, aridity had no significant effects on leaf nitrogen or phosphorus stoichiometry, while high salinity significantly increased the leaf N:P ratio and there were no significant interactions between the aridity and salinity conditions. No significant effects of soil nutrient gradients were observed on plant N and P stoichiometric characteristics at the individual or community levels. These results suggest that individual desert plants have lower leaf N and P concentrations to adapt to extreme drought and only adapt to salt stress through higher leaf N concentrations. The N and P stoichiometric characteristics of desert plant communities are not sensitive to variations in aridity and salinity in this extreme habitat. The results of this study could enhance our perceptions of plant adaptation mechanisms to extreme habitats within terrestrial ecosystems. [ABSTRACT FROM AUTHOR]

Background: Deep-sea mussels living in the cold seeps with enormous biomass act as the primary consumers. They are well adapted to the extreme environment where light is absent, and hydrogen sulfide, methane, and other hydrocarbon-rich fluid seepage occur. Despite previous studies on diversity, role, evolution, and symbiosis, the changing adaptation patterns during different developmental stages of the deep-sea mussels remain largely unknown. Results: The deep-sea mussels (Bathymodiolus platifrons) of two developmental stages were collected from the cold seep during the ocean voyage. The gills, mantles, and adductor muscles of these mussels were used for the Illumina sequencing. A total of 135 Gb data were obtained, and subsequently, 46,376 unigenes were generated using de-novo assembly strategy. According to the gene expression analysis, amounts of genes were most actively expressed in the gills, especially genes involved in environmental information processing. Genes encoding Toll-like receptors and sulfate transporters were up-regulated in gills, indicating that the gill acts as both intermedium and protective screen in the deep-sea mussel. Lysosomal enzymes and solute carrier responsible for nutrients absorption were up-regulated in the older mussel, while genes related to toxin resistance and autophagy were up-regulated in the younger one, suggesting that the older mussel might be in a vigorous stage while the younger mussel was still paying efforts in survival and adaptation. Conclusions: In general, our study suggested that the adaptation capacity might be formed gradually during the development of deep-sea mussels, in which the gill and the symbionts play essential roles. [ABSTRACT FROM AUTHOR]

Variation in gene expression can provide insights into organismal responses to environmental stress and physiological mechanisms mediating adaptation to habitats with contrasting environmental conditions. We performed an RNA-sequencing experiment to quantify gene expression patterns in fish adapted to habitats with different combinations of environmental stressors, including the presence of toxic hydrogen sulphide (H2 S) and the absence of light in caves. We specifically asked how gene expression varies among populations living in different habitats, whether population differences were consistent among organs, and whether there is evidence for shared expression responses in populations exposed to the same stressors. We analysed organ-specific transcriptome-wide data from four ecotypes of Poecilia mexicana (nonsulphidic surface, sulphidic surface, nonsulphidic cave and sulphidic cave). The majority of variation in gene expression was correlated with organ type, and the presence of specific environmental stressors elicited unique expression differences among organs. Shared patterns of gene expression between populations exposed to the same environmental stressors increased with levels of organismal organization (from transcript to gene to physiological pathway). In addition, shared patterns of gene expression were more common between populations from sulphidic than populations from cave habitats, potentially indicating that physiochemical stressors with clear biochemical consequences can constrain the diversity of adaptive solutions that mitigate their adverse effects. Overall, our analyses provided insights into transcriptional variation in a unique system, in which adaptation to H2 S and darkness coincide. Functional annotations of differentially expressed genes provide a springboard for investigating physiological mechanisms putatively underlying adaptation to extreme environments.

Classical reductionist experimentation tends to conceptually compartmentalise mitigation and adaptation into binary categories, shielding insight into how greenhouse gas (GHG) emissions and climate change interact. Here, our primary aim was to examine how a key tenant of the global climate crisis – drought – is likely to influence soil organic carbon (SOC). We deconstruct these paradigms using case study farms in Tasmania, Australia, using state of the art models to simulate pasture production and SOC under historical and 2050 climates, the latter encapsulating more frequent extreme weather events. We show that longitudinal changes in SOC stocks correlate positively with standard precipitation evapotranspiration index (SPEI) via the mediating effects of seasonal pasture growth. Drought elicited notable SOC losses, particularly when antecedent SOC stocks were high, whereas high rainfall years amplified SOC sequestration. Renovating pastures with perennial legumes enhanced sequestration under 2050 climates, as did introducing irrigation and increasing soil fertility. In most cases however, the influence of aridity on SOC dominated over that of farm management, suggesting that climate change - and by extension, seasonal rainfall distribution - are likely to engender greater influence on SOC stocks compared with farm management or practice change. As such, aspirations to maintain SOC stocks at ceiling levels over the long-term are likely to be challenged by the changing climate and particularly drought. Even so, we contend that adoption of practices aimed at improving soil organic matter can benefit productivity through enhancement of soil fertility, water-holding capacity and health, and as such should be encouraged, particularly where status quo agro-ecosystems are degraded. • We explored how soil organic carbon (SOC) stocks are influenced by drought. • High seasonal rainfall was conducive to improved SOC sequestration. • Drought elicited high SOC losses, particularly when antecedent SOC stocks were high. • Deep-rooted perennials, additional irrigation and fertiliser improved SOC accrual. • SOC accrual was greatest for zones with degradation and/or suboptimal productivity. [ABSTRACT FROM AUTHOR]

The mangrove rivulus (Kryptolebias marmoratus) is one of two preferentially self-fertilizing hermaphroditic vertebrates. This mode of reproduction makes mangrove rivulus an important model for evolutionary and biomedical studies because long periods of self-fertilization result in naturally homozygous genotypes that can produce isogenic lineages without significant limitations associated with inbreeding depression. Over 400 isogenic lineages currently held in laboratories across the globe show considerable among-lineage variation in physiology, behavior, and life history traits that is maintained under common garden conditions. Temperature mediates the development of primary males and also sex change between hermaphrodites and secondary males, which makes the system ideal for the study of sex determination and sexual plasticity. Mangrove rivulus also exhibit remarkable adaptations to living in extreme environments, and the system has great promise to shed light on the evolution of terrestrial locomotion, aerial respiration, and broad tolerances to hypoxia, salinity, temperature, and environmental pollutants. Genome assembly of the mangrove rivulus allows the study of genes and gene families associated with the traits described above. Here we present a de novo assembled reference genome for the mangrove rivulus, with an approximately 900 Mb genome, including 27,328 annotated, predicted, protein-coding genes. Moreover, we are able to place more than 50% of the assembled genome onto a recently published linkage map. The genome provides an important addition to the linkage map and transcriptomic tools recently developed for this species that together provide critical resources for epigenetic, transcriptomic, and proteomic analyses. Moreover, the genome will serve as the foundation for addressing key questions in behavior, physiology, toxicology, and evolutionary biology.

Hydrogen sulfide (H2S) is a potent toxicant interfering with oxidative phosphorylation in mitochondria and creating extreme environmental conditions in aquatic ecosystems. The mechanistic basis of adaptation to perpetual exposure to H2S remains poorly understood. We investigated evolutionarily independent lineages of livebearing fishes that have colonized and adapted to springs rich in H2S and compared their genome-wide gene expression patterns with closely related lineages from adjacent, nonsulfidic streams. Significant differences in gene expression were uncovered between all sulfidic and nonsulfidic population pairs. Variation in the number of differentially expressed genes among population pairs corresponded to differences in divergence times and rates of gene flow, which is consistent with neutral drift driving a substantial portion of gene expression variation among populations. Accordingly, there was little evidence for convergent evolution shaping large-scale gene expression patterns among independent sulfide spring populations. Nonetheless, we identified a small number of genes that was consistently differentially expressed in the same direction in all sulfidic and nonsulfidic population pairs. Functional annotation of shared differentially expressed genes indicated upregulation of genes associated with enzymatic H2S detoxification and transport of oxidized sulfur species, oxidative phosphorylation, energy metabolism, and pathways involved in responses to oxidative stress. Overall, our results suggest that modification of processes associated with H2S detoxification and toxicity likely complement each other to mediate elevated H2S tolerance in sulfide spring fishes. Our analyses allow for the development of novel hypotheses about biochemical and physiological mechanisms of adaptation to extreme environments.

The Qinghai–Tibet Plateau (QTP) sensu lato (sl) houses an exceptional species diversity in Asia. To develop a comprehensive understanding of species diversity in this fascinating region, we reviewed recent progress from biogeographic, paleogeographic, paleontological and genomic research of both plants and animals in the QTPsl. Numerous studies have been conducted to examine whether the QTPsl uplift triggered the production of rich species diversity there, whether a Quaternary "unified ice sheet" eliminated plants and animals on the central plateau and how high‐altitude species developed the extreme environment adaptations. Major disputes arose about the first issue, mainly from different understanding of the QTP circumscriptions and related uplift, inaccurate dating of molecular phylogenetic trees, and non‐causal correlations between uplift and species diversification. The QTPsl uplift is spatially and temporally heterogeneous, and abundant fossils reported recently similarly support such an asynchronous upheaval model across the entire region. Available phylogeographic studies of alpine plants and animals suggested their glacial refugia in the central QTPsl, rejecting a unified ice sheet during the Last Glacial Maximum. Genomic evidence from a limited number of alpine species has identified numerous candidate genes for high‐altitude adaptation. In the future, more studies should be focused on speciation and adaptation mechanisms of the alpine species in the QTPsl based on the cutting‐edge methods. [ABSTRACT FROM AUTHOR]

Grounded within a multidimensional and multilevel approach, the aim of this study was to investigate the time course of Psychological Adaptation Process (PAP) dimensions (social, emotional, occupational, and physical) during one-year polar winter-overs in Subantarctic and Antarctic stations. The effects of perceived control (PC) at the start of polar winter on the dynamics of the PAP dimensions were also examined. The present findings clarify some changes in PAP in extreme environments: (a) The dimensions of psychological adaptation evolved differently as a function of environmental conditions; and (b) PC influenced the trajectories of PAP dimensions. These findings elucidate the importance and complexity of psychological dimensions and the significant role of PC in adaptation to an extreme environment. • Details drawing the outlines of adaptation in extreme environments. • Psychological adaptation dimensions evolved differently according to the environmental conditions. • Perceived Control influenced the trajectories of PAP dimensions. [ABSTRACT FROM AUTHOR]

Nature-Based Solutions (NBSs) promise a future where natural, human and technical elements help solving many of the issues plaguing cities. Pollution reduction, increased human wellbeing and climate change adaptation are only some of the challenges targeted by NBSs. However, under the warming climate affecting many of the world's cities, most of modern NBSs will be highly impacted by the same climate factors they hope to mitigate. As in the case of extreme temperatures or altered water availability, these factors can impact and cause the failure in the organisms, technical elements and governance structures that NBSs rely upon, thus decreasing performance, reliability and sustainability of these solutions. In this commentary we propose critical considerations related to designing, building and managing " climate-ready" NBSs – defined as local integrated solutions able to cope with or adapt to climate change. We do so by highlighting examples in heat- and drought-stricken areas across Australian cities as they sit at the global forefront of a hotter world. We discuss in detail i) tolerance and adaptability of NBS to new climates, ii) NBS design for weather extremes and climate-safety margins, iii) NBS trialing and prototyping, and iv) planning for " climate-ready " NBSs. In doing so, we highlight caveats and limitations to propose an implementation framework to make NBSs not only work, but succeed, in a hotter urban world; one that sees 50 °C as a critical limit to sustain urban life and nature. [ABSTRACT FROM AUTHOR]

Sampling and genomic efforts over the past decade have revealed an enormous quantity and diversity of life in Earth's extreme environments. This new knowledge of life on Earth poses the challenge of understandingits molecular basis in such inhospitable conditions, given that such conditions lead to loss of structure and of function in biomolecules from mesophiles. In this review, we discuss the physicochemical properties of extreme environments. We present the state of recent progress in extreme environmental genomics. We then present an overview of our current understanding of the biomolecular adaptation to extreme conditions. As our current and future understanding of biomolecular structure–function relationships in extremophiles requires methodologies adapted to extremes of pressure, temperature, and chemical composition, advances in instrumentation for probing biophysical properties under extreme conditions are presented. Finally, we briefly discuss possible future directions in extreme biophysics. [ABSTRACT FROM AUTHOR]

The southern Persian/Arabian Gulf experiences extreme seasonal temperature variation (> 20 °C) making it among the most hostile reef environments on Earth. Previous anecdotal evidence has suggested that seasonal temperature changes may influence regional reef fish assemblages, but to date research has been limited. To examine the influence of temperature on reef fish abundance and composition, we performed visual surveys in summer and in winter over three years at three reefs in the southern Gulf (Dhabiya, Saadiyat and Ras Ghanada). Overall abundance of fishes was 40% higher in summer than in winter, and multivariate analyses showed strong and significant differences in overall seasonal community structure, consistent at all sites and across all years. Seasonal differences were largely driven by nine of the 30 observed species, which together accounted for 70% of the divergence in community structure between summer and winter. Of these nine species, Lutjanus ehrenbergii, Lutjanus fulviflamma, Plectorhinchus sordidus and Abudefduf vaigiensis were significantly more abundant in summer, Parupeneus margaritatus and Acanthopagrus bifasciatus, were significantly more common on reefs in winter. We discuss these changes in terms of seasonal physiological and ecological constraints, and explore the implications of these changes on the functional ecology of reef fishes in this thermally variable and extreme environment. [ABSTRACT FROM AUTHOR]

Although persistent efforts have identified and characterized a few candidate genes and related biological processes with potential functions in the adaptation of many species to extreme environments, few works have been conducted to determine the genomic basis of adaptation in endangered livestock breeds that have been living in extreme conditions for more than thousands of years. To fill this gap, we sequenced the whole genomes of nine individuals from three Chinese native endangered cattle breeds that are living in high‐altitude or arid environments. Phylogenetic and evolutionary history analyses of these three and other six breeds showed that the genetic structure of the cattle populations is primarily related to geographic location. Interestingly, we identified pervasive introgression from the yak to Zhangmu cattle (ZMC) that cover several genes (e.g., NOS2, EGLN1 and EPAS1) involved in the hypoxia response and previously identified as positive selection genes in other species, which suggested that the adaptive introgression from yak may have contributed to the adaptation of ZMC to high‐altitude environments. In addition, by contrasting the breeds in opposite living conditions, we revealed a set of candidate genes with various functions from hypoxia response, water metabolism, immune response and body shape change to embryo development and skeletal system development, etc., that may be related to high‐altitude or arid adaptation. Our research provides new insights into the recovery and adaptation of endangered native cattle and other species in extreme environments and valuable resources for future research on animal husbandry to cope with climate change. [ABSTRACT FROM AUTHOR]

Extremophilic microbes have adapted to thrive in ecological niches characterized by harsh chemical/physical conditions such as, for example, very low/high temperature. Living organisms inhabiting these environments have developed peculiar mechanisms to cope with extreme conditions, in such a way that they mark the chemical-physical boundaries of life on Earth. Studying such mechanisms is stimulating from a basic research viewpoint and because of biotechnological applications. Pseudoalteromonas species are a group of marine gamma-proteobacteria frequently isolated from a range of extreme environments, including cold habitats and deep-sea sediments. Since deep-sea floors constitute almost 60% of the Earth's surface and cold temperatures represent the most common of the extreme conditions, the genus Pseudoalteromonas can be considered one of the most important model systems for studying microbial adaptation. Particularly, among all Pseudoalteromonas representatives, P. haloplanktis TAC125 has recently gained a central role. This bacterium was isolated from seawater sampled along the Antarctic ice-shell and is considered one of the model organisms of cold-adapted bacteria. It is capable of thriving in a wide temperature range and it has been suggested as an alternative host for the soluble overproduction of heterologous proteins, given its ability to rapidly multiply at low temperatures. In this review, we will present an overview of the recent advances in the characterization of Pseudoalteromonas strains and, more importantly, in the understanding of their evolutionary and chemical-physical strategies to face such a broad array of extreme conditions. A particular attention will be given to systems-biology approaches in the study of the above-mentioned topics, as genome-scale datasets (e.g. genomics, proteomics, phenomics) are beginning to expand for this group of organisms. In this context, a specific section dedicated to P. haloplanktis TAC125 will be presented to address the recent efforts in the elucidation of the metabolic rewiring of the organisms in its natural environment (Antarctica). • Pseudoalteromonas is a model bacterial genus for studying the adaptation to extreme environments. • To survive at low temperatures Pseudoalteromonas strains have developed unique strategies. • Pseudoalteromonas strains are exciting and promising from a biotechnological viewpoint. • Systems-biology approaches are central in the study of microbial adaptation. [ABSTRACT FROM AUTHOR]

The advantages of microbial induced carbonate mineralization for soil-stabilization and building-material industries are under extensive investigation. The pH is one of the influential parameters on the desired calcium carbonate mineralization due to the resulting textures of this mineral. Moreover, the decrease in microbial growth under the extreme alkaline environment compatible with the sustainability of concrete has been the bottleneck for an effective application of Microbial Induced Carbonate Precipitation (MICP) in the concrete industry. Microbial consortia have shown more robustness in their resistance to environmental fluctuations than pure cultures. In addition, microorganisms obtained from alkaline environments could facilitate their adaptation to extreme alkalinity. The aim of this study was to obtain urease producing bacteria (UPB) able to maintain a high MICP performance under extremely alkaline conditions compatible with concrete by adapting native microorganisms obtained from extreme environments. The growth performance, urease activity, strength of the generated biocement, and CaCO 3 mineralogy were compared with the best-performer urease-producing bacteria (UPB), S. pasteurii DSMZ 33. The native bacteria presented a similar performance in growth and urease activity than S. pasteurii under extreme alkaline conditions (pH 12.5). However, the generated biocement of native Sporosarcina sp. achieved 461 % more unconfined compressive strength (UCS) and 120 % more CaCO 3 content than the biocement generated by S. pasteurii DSMZ 33. The careful adaptation process performed in this study for native UPB and S. pasteurii DSMZ 33 is an interesting approach with promising and projectable results for future engineering and biotechnological applications. These results have important implications for the design of engineering solutions involving MICP. A consolidated and strong biocement was generated by a native species obtained from extreme ecosystems in an effort of bioprospecting to enhance the performance of biotechnological solutions for geotechnical applications in the concrete and soil-improvement industries. Biocement generated by the native species was stronger than the generated by one of the best-described biocementation performers. This native species was able to actively growing and do perform microbial-induced-carbonate-mineralization under extreme alkalinity conditions after a careful laboratory adaptation process. The native species presented unique and differentiating traits that gave it a better adaptability and biocementation performance. The same occurs with a priceless microbial diversity inhabiting little explored and unprotected extreme ecosystems. Extreme environments house a fascinating biodiversity with potential value for ecosystem services. Image, graphical abstract [ABSTRACT FROM AUTHOR]

Human adaptation to extreme environments has been explored for over a century to understand human psychology, integrated physiology, comparative pathologies, and exploratory potential. It has been demonstrated that these environments can provide multiple external stimuli and stressors, which are sufficient to disrupt internal homeostasis and induce adaptation processes. Multiday hyperbaric and/or saturated (HBS) environments represent the most understudied of environmental extremes due to inherent experimental, analytical, technical, temporal, and safety limitations. National Aeronautic Space Agency (NASA) Extreme Environment Mission Operation (NEEMO) is a space-flight analog mission conducted within Florida International University's Aquarius Undersea Research Laboratory (AURL), the only existing operational and habitable undersea saturated environment. To investigate human objective and subjective adaptations to multiday HBS, we evaluated aquanauts living at saturation for 9–10 days via NASA NEEMO 22 and 23, across psychologic, cardiac, respiratory, autonomic, thermic, hemodynamic, sleep, and body composition parameters. We found that aquanauts exposed to saturation over 9–10 days experienced intrapersonal physical and mental burden, sustained good mood and work satisfaction, decreased heart and respiratory rates, increased parasympathetic and reduced sympathetic modulation, lower cerebral blood flow velocity, intact cerebral autoregulation and maintenance of baroreflex functionality, as well as losses in systemic bodyweight and adipose tissue. Together, these findings illustrate novel insights into human adaptation across multiple body systems in response to multiday hyperbaric saturation. [ABSTRACT FROM AUTHOR]

Although soil-borne methanogens are known to be highly diverse and adapted to extreme environments, their application as potential (anaerobic) inocula to improve anaerobic digestion has not been investigated until now. The present study aimed at evaluating if soil-derived communities can be beneficial for biogas (methane, CH4) production and endure unfavorable conditions commonly associated with digestion failure. Nine study sites were chosen and tested for suitability as inoculation sources to improve biogas production via in situ measurements (CH4 fluxes, physical and chemical soil properties, and abundance of methanogens) and during a series of anaerobic digestions with (a) combinations of both sterile or unsterile soil and diluted fermenter sludge, and (b) pH-, acetate-, propionate-, and ammonium-induced disturbance. Amplicon sequencing was performed to assess key microbial communities pivotal for successful biogas production. Four out of nine tested soil inocula exerted sufficient methanogenic activity and repeatedly allowed satisfactory CH4/biogas production even under deteriorated conditions. Remarkably, the significantly highest CH4 production was observed using unsterile soil combined with sterile sludge, which coincided with both a higher relative abundance of methanogens and predicted genes involved in CH4 metabolism in these variants. Different bacterial and archaeal community patterns depending on the soil/sludge combinations and disturbance variations were established and these patterns significantly impacted CH4 production. Methanosarcina spp. seemed to play a key role in CH4 formation and prevailed even under stressed conditions. Overall, the results provided evidence that soil-borne methanogens can be effective in enhancing digestion performance and stability and, thus, harbor vast potential for further exploitation. [ABSTRACT FROM AUTHOR]

Hydrothermal vents are unique deep‐sea environments exhibiting extreme temperature gradients and toxic concentrations of H2S that limit the growth of biological communities. Notably, some decapod crustaceans are the dominant organisms inhabiting these environments, and share similar phenotypic and physiological traits, such as white body coloration and chemosynthetic capacity. However, a lack of genomic information has precluded an understanding of these convergent phenotypes. Here, comparative transcriptomic analyses were performed in 14 decapod species, including four deep‐sea hydrothermal vent species and 10 shallow‐water relatives. Phylogenetic analysis suggested that the four deep‐sea species stemmed from different ancestors despite being geographically close, and therefore their similar traits were probably the product of convergent evolution rather than lineal inheritance. A total of 391 positively selected genes, 109 parallel substituted genes and 33 significantly expanded gene families were identified in the deep‐sea decapods. Among these, only the SNARE interactions in vesicular transport pathway was significantly enriched, with both positively selected genes and parallel substituted genes, suggesting that specific macromolecule transport might be a strong convergent evolution trait in deep‐sea decapods. Furthermore, many genes involved in protein synthesis, processing and energy metabolism were detected under convergent evolution, suggesting a role for adaptive evolution in association with a specific metabolic pathway in response to chemosynthetic nutrition patterns. Moreover, our study suggests that convergently evolved white body colour might have resulted from the contraction of the crustacyanin gene family and the low content of astaxanthin in the body of deep‐sea decapods. Therefore, this study provides valuable genetic evidence for convergent evolution in deep‐sea decapods. [ABSTRACT FROM AUTHOR]

In late July 2018, we studied the chemical composition of the water and benthic communities in two hydrogen sulfide springs in the catchment of the Iska-Shor Creek (lefthand tributary of the Usa River), as well as zoobenthos and plankton in the Usa River around the creek’s mouth. Compared to the reference site, water in the springs contained manyfold higher concentrations of chlorine, sodium, calcium, sulfate ions, and differed in the content of organic matter, heavy metals, and several micro elements. Water temperature did not exceed +6 °С. Zoobenthos abundance and biomass was low, comprising31 taxa of invertebrates. Chironomid larvae and harpacticoids prevailed. Chironomids were the most diverse group in the creek – 20 taxa, of which 17 were found directly in the springs. Tanytarsus verralli Goetghebuer, 1928 was the most numerous species. Apart from chironomids, we found nematodes, ostracods, cladocerans, first instar larvae of mayflies, stoneflies and caddisflies, and others Dipteran families. The diversityof planktic and benthic invertebrates, and the set of dominant species showed little variation among the sites surveyed in the Usa River. The dominants in terms of abundance in the river’s benthic fauna were chironomid species from the subfamily Chironomini: Tanytarsus verralli, Cladotanytarsus (Cladotanytarsus) mancus (Walker, 1856), and Polypedilum (Pentapedilum) exsectum (Kieffer 1916). The share of roundworms decreased and the share of cyclops and water mites increased in the zoobenthos of the river downstream from the mouth of the creek. Among zooplankton dominants, the abundance of Euchlanis dilatata Ehrenberg, 1832 decreased and the share of Cladocera from the genus Bosmina increased downstream the river. Inside the area directly affected bythe mineral water springs, we found a high abundance of euplanktic rotifers Asplanchna priodonta Gosse, 1850 and copepods Mesocyclops leuckarti (Claus, 1857), as well asan increased abundance of juvenile Cyclopoida. The studies have expanded our knowledge of the adaptive capabilities of invertebrates, and the ecology of aquatic communities forming in this extreme environment.

Insects are the most evolutionarily and ecologically successful group of living animals, being present in almost all possible mainland habitats; however, they are virtually absent in the ocean, which constitutes more than 99% of the Earth’s biosphere. Only a few insect species can be found in the sea but they remain at the surface, in salt marshes, estuaries, or shallow waters. Remarkably, a group of 13 species manages to endure long immersion periods in the open sea, as well as deep dives, i.e., seal lice. Sucking lice (Phthiraptera: Anoplura) are ectoparasites of mammals, living while attached to the hosts’ skin, into their fur, or among their hairs. Among them, the family Echinophthiriidae is peculiar because it infests amphibious hosts, such as pinnipeds and otters, who make deep dives and spend from weeks to months in the open sea. During the evolutionary transition of pinnipeds from land to the ocean, echinophthiriid lice had to manage the gradual change to an amphibian lifestyle along with their hosts, some of which may spend more than 80% of the time submerged and performing extreme dives, some beyond 2000 m under the surface. These obligate and permanent ectoparasites have adapted to cope with hypoxia, high salinity, low temperature, and, in particular, conditions of huge hydrostatic pressures. We will discuss some of these adaptations allowing seal lice to cope with their hosts’ amphibious habits and how they can help us understand why insects are so rare in the ocean.

Anthropogenic extreme environments are emphasized as interesting sites for the study of evolutionary pathways, biodiversity, and extremophile bioprospection. Organisms that grow under these conditions are usually regarded as extremophiles; however, the extreme novelty of these environments may have favor adaptive radiations of facultative extremophiles. At the Iberian Peninsula, uranium mining operations have rendered highly polluted extreme environments in multiple locations. In this study, we examined the phytoplankton diversity, community structure, and possible determining factors in separate uranium mining-impacted waters. Some of these human-induced extreme environments may be able to sustain indigenous facultative extremophile phytoplankton species, as well as alleged obligate extremophiles. Therefore, we investigated the adaptation capacity of three laboratory strains, two Chlamydomonas reinhardtii and a Dictyosphaerium chlorelloides, to uranium-polluted waters. The biodiversity among the sampled waters was very low, and despite presenting unique taxonomic records, ecological patterns can be identified. The microalgae adaptation experiments indicated a gradient of ecological novelty and different phenomena of adaptation, from acclimation in some waters to non-adaptation in the harshest anthropogenic environment. Certainly, phytoplankton extremophiles might have been often overlooked, and the ability to flourish in extreme environments might be a functional feature in some neutrophilic species. Evolutionary biology and microbial biodiversity can benefit the study of recently evolved systems such as uranium-polluted waters. Moreover, anthropogenic extremophiles can be harnessed for industrial applications. [ABSTRACT FROM AUTHOR]