ANTARCTIC VASCULAR PLANTS SUCH AS DESCHAMPSIA ANTARCTICA (DA) COULD GENERATE MORE SUITABLE MICRO-ENVIRONMENTAL CONDITIONS FOR THE ESTABLISHMENT OF OTHER PLANTS LIKE COLOBANTHUS QUITENSIS (CQ). ALTHOUGH POSITIVE PLANT?PLANT INTERACTIONS HAVE BEEN SHOWN TO CONTRIBUTE TO PLANT PERFORMANCE AND ESTABLISHMENT, LITTLE IS KNOWN ABOUT HOW MICROORGANISMS MIGHT MODULATE THOSE INTERACTIONS, PARTICULARLY IN STRESSFUL ENVIRONMENTAL CONDITIONS. SEVERAL REPORTS HAVE FOCUSED ON THE POSSIBLE ECOLOGICAL ROLES OF MICROORGANISMS ON VASCULAR PLANTS, BUT IF RHIZOSPHERIC MICROORGANISMS CAN IMPACT POSITIVE INTERACTIONS AMONG ANTARCTIC PLANTS HAS BEEN SELDOM STUDIED. HERE, WE ASSESSED THE PHYSICAL?CHEMICAL CHARACTERISTICS OF RHIZOSPHERIC SOILS FROM CQ GROWING ALONE OR ASSOCIATED WITH DA (CQ?+?DA). IN ADDITION, WE COMPARED THE RHIZOSPHERE MICROBIOMES ASSOCIATED WITH CQ, EITHER GROWING ALONE OR ASSOCIATED WITH DA (CQ?+?DA), USING A SHOTGUN METAGENOMIC DNA SEQUENCING APPROACH AND USING EGGNOG FOR COMPARATIVE AND FUNCTIONAL METAGENOMICS. OVERALL, THERE WERE NO DIFFERENCES AMONG RHIZOSPHERIC SOILS IN TERMS OF PHYSICAL?CHEMICAL CHARACTERISTICS. ON THE OTHER HAND, OUR RESULTS SHOW SIGNIFICANT DIFFERENCES IN TERMS OF TAXONOMIC DIVERSITY BETWEEN RHIZOSPHERIC SOILS. FUNCTIONAL ANNOTATION AND PATHWAY ANALYSIS SHOWED THAT MICROORGANISMS FROM RHIZOSPHERIC SOIL SAMPLES ALSO HAVE SIGNIFICANT DIFFERENCES IN GENE ABUNDANCE ASSOCIATED WITH SEVERAL FUNCTIONAL CATEGORIES RELATED TO ENVIRONMENTAL TOLERANCE AND IN METABOLIC PATHWAYS LINKED TO OSMOTIC STRESS, AMONG OTHERS. OVERALL, THIS STUDY PROVIDES FOUNDATIONAL INFORMATION WHICH WILL ALLOW TO EXPLORE THE BIOLOGICAL IMPACT OF THE RHIZOBIOME AND ITS FUNCTIONAL MECHANISMS AND MOLECULAR PATHWAYS ON PLANT PERFORMANCE AND HELP EXPLAIN THE CONCERTED STRATEGY DEPLOYED BY CQ TO INHABIT AND COPE WITH THE HARSH CONDITIONS PREVAILING IN ANTARCTICA.

STUDYING POPULATION STRUCTURE HAS MADE AN ESSENTIAL CONTRIBUTION TO UNDERSTANDING EVOLUTIONARY PROCESSES AND DEMOGRAPHIC HISTORY IN FOREST ECOLOGY RESEARCH. THIS INFERENCE PROCESS BASICALLY INVOLVES THE IDENTIFICATION OF COMMON GENETIC VARIANTS AMONG INDIVIDUALS, THEN GROUPING THE SIMILAR INDIVIDUALS INTO SUBPOPULATIONS. IN THIS STUDY, A SPECTRAL-BASED CLASSIFICATION OF GENETICALLY DIFFERENTIATED GROUPS WAS CARRIED OUT USING A PROVENANCE?PROGENY TRIAL OF EUCALYPTUS CLADOCALYX. FIRST, THE GENETIC STRUCTURE WAS INFERRED THROUGH A BAYESIAN ANALYSIS USING SINGLE-NUCLEOTIDE POLYMORPHISMS (SNPS). THEN, DIFFERENT MACHINE LEARNING MODELS WERE TRAINED WITH FOLIAR SPECTRAL INFORMATION TO ASSIGN INDIVIDUAL TREES TO SUBPOPULATIONS. THE RESULTS REVEALED THAT SPECTRAL-BASED CLASSIFICATION USING THE MULTILAYER PERCEPTRON METHOD WAS VERY SUCCESSFUL AT CLASSIFYING INDIVIDUALS INTO THEIR RESPECTIVE SUBPOPULATIONS (WITH AN AVERAGE OF 87% OF CORRECT INDIVIDUAL ASSIGNMENTS), WHEREAS 85% AND 81% OF INDIVIDUALS WERE ASSIGNED TO THEIR RESPECTIVE CLASSES CORRECTLY BY CONVOLUTIONAL NEURAL NETWORK AND PARTIAL LEAST SQUARES DISCRIMINANT ANALYSIS, RESPECTIVELY. NOTABLY, 93% OF INDIVIDUAL TREES WERE ASSIGNED CORRECTLY TO THE CLASS WITH THE SMALLEST SIZE USING THE SPECTRAL DATA-BASED MULTI-LAYER PERCEPTRON CLASSIFICATION METHOD. IN CONCLUSION, SPECTRAL DATA, ALONG WITH NEURAL NETWORK MODELS, ARE ABLE TO DISCRIMINATE AND ASSIGN INDIVIDUALS TO A GIVEN SUBPOPULATION, WHICH COULD FACILITATE THE IMPLEMENTATION AND APPLICATION OF POPULATION STRUCTURE STUDIES ON A LARGE SCALE.

ANTARCTICA IS ONE OF THE MOST EXTREME ENVIRONMENTS FOR VASCULAR PLANTS OCCURRENCE WORLDWIDE, AND ONLY TWO NATIVE VASCULAR PLANTS HAVE COLONIZED THIS CONTINENT: DESCHAMPSIA ANTARCTICA AND COLOBANTHUS QUITENSIS. NEVERTHELESS, IN RECENT YEARS, SEVERAL ALIEN PLANT SPECIES HAS BEEN FOUND IN ANTARCTICA WITH NEGATIVE EFFECTS ON THE NATIVE FLORA. IN THIS STUDY, WE SHOW A RECOLONIZATION RECORD OF THE MOST WIDESPREAD PLANT INVADER IN ANTARCTICA (POA ANNUA) AND THE RISK OF A POTENTIAL SPREADING IN A HIGHLY VISITED SITE ON THE ANTARCTIC PENINSULA. OVERALL, TWO NEW P. ANNUA INDIVIDUALS WERE RECORDED, WHERE FOUR SPECIMENS WERE PREVIOUSLY REPORTED AND REMOVED IN 2010, SUGGESTING THAT EITHER A PROPAGULE LOAD IS CONTINUOUS, OR THAT A SEED BANK PREVAILED IN THE SITE. ON THE OTHER HAND, THE SPREADING MODELING SUGGESTS THAT THE PROBABILITY TO COLONIZE AND SPREADING OF P. ANNUA INCREASES NOTORIOUSLY WITH THE POSSIBILITY OF DISPERSION OF PROPAGULES, WITH CONSEQUENT RISK OF DISPLACEMENT FOR THE NATIVE FLORA. BIOLOGICAL INVASIONS ARE A MAJOR THREAT TO THE INTEGRITY OF NATIVE BIODIVERSITY IN ALL BIOMES, AND THEY HAVE THE POTENTIAL TO CHANGE IRREVERSIBLY ANTARCTICA?S FRAGILE ECOSYSTEMS.

IN STRESSFUL ENVIRONMENTS, A NURSE PLANT CAN AMELIORATE HARSH BIOTIC AND ABIOTIC CONDITIONS FOR ANOTHER PLANT SPECIES THAT GROWS WITHIN ITS CANOPY. THIS CANOPY CAN ACT AS A BARRIER FOR HERBIVORES, REDUCING DAMAGE TO THE PROTECTED PLANTS INSIDE, BUT IT CAN ALSO REDUCE ACCESS TO POLLINATORS POSSIBLY RESULTING IN A TRADEOFF BETWEEN SURVIVAL AND REPRODUCTIVE OUTPUT. IN A SEMI-ARID ECOSYSTEM, THE SHRUB PORLIERIA CHILENSIS ACTS AS A NURSE, INCREASING SOIL MOISTURE, NUTRIENTS AND REDUCING TEMPERATURE INSIDE ITS CANOPY COMPARED TO OPEN AREAS. FLOURENSIA THURIFERA IS ONE OF THE BENEFICIARY SHRUBS THAT CAN GROW INSIDE P. CHILENSIS, WHERE IT SHOWS INCREASED SURVIVAL AND PERFORMANCE COMPARED TO OPEN AREAS. HOWEVER, GROWING INSIDE P. CHILENSIS? CANOPY MAY REDUCE POLLINATOR VISIT. WE AIM TO EVALUATE THE POSSIBLE TRADEOFF BETWEEN SURVIVAL AND REPRODUCTION IN F. THURIFERA INDIVIDUALS GROWING INSIDE AND OUTSIDE THE CANOPY OF P. CHILENSIS. THIS WAS ACHIEVED THROUGH A FIELD EXPERIMENT WERE WE MEASURED SURVIVAL, POLLINATOR VISITS AND SEED OUTPUT OF F. THURIFERA PLANTS GROWING INSIDE AND OUTSIDE THE CANOPY OF P. CHILENSIS. FLOURENSIA THURIFERA INDIVIDUALS HAD A HIGHER SURVIVAL WHEN GROWING WITHIN THE CANOPY OF P. CHILENSIS AND HAD LOWER POLLINATOR VISITS AND SEED OUTPUT COMPARED TO PLANTS GROWING IN OPEN AREAS. THUS, WE FOUND A SIGNIFICANT NEGATIVE CORRELATION BETWEEN PLANT SURVIVAL AND SEED OUTPUT CONSIDERING BOTH CONDITIONS (INSIDE OR OUTSIDE NURSES), EVIDENCING A TRADEOFF BETWEEN THESE TRAITS. THE TRADEOFF EVIDENCED HERE COULD HAVE LARGE IMPACT AT THE POPULATION AND COMMUNITY LEVEL. ON ONE HAND, THIS TRADEOFF COULD MASK POSSIBLE NURSE EFFECTS IN OTHER SPECIES, SINCE THEY COULD SHOW A SIMILAR NET FITNESS IN BOTH MICROHABITAT (INSIDE OR OUTSIDE NURSES). FINALLY, WE PROPOSE A THEORETICAL MODEL TO ASSESS THE CHANGE IN THE SHAPE OF THIS TRADEOFF UNDER FUTURE CLIMATIC CONDITIONS WHERE TEMPERATURE AND PRECIPITATION ARE PREDICTED TO VARY DUE TO CLIMATE CHANGE.

ANTARCTICA IS ONE OF THE LESS PRONE ENVIRONMENTS FOR PLANT INVASIONS, NEVERTHELESS A GROWING NUMBER OF NON-NATIVE SPECIES HAVE BEEN REGISTERED IN THE LAST DECADES WITH NEGATIVE EFFECTS ON NATIVE FLORA. HERE WE ASSESSED ADAPTIVE PHENOTYPIC PLASTICITY IN THREE PHOTOPROTECTIVE TRAITS (NON-PHOTOCHEMICAL QUENCHING, TOTAL SOLUBLE SUGARS, AND DE-EPOXIDATION STATE OF XANTHOPHYLLS CYCLE), AND FITNESS-RELATED TRAITS (MAXIMUM QUANTUM YIELD, PHOTOSYNTHETIC RATE AND TOTAL BIOMASS) IN THE INVASIVE SPECIES POA ANNUA AND DESCHAMPSIA ANTARCTICA UNDER CURRENT CONDITIONS OF WATER AVAILABILITY AND THOSE PROJECTED BY CLIMATE CHANGE MODELS. IN ADDITION, TWO MANIPULATIVE EXPERIMENTS IN CONTROLLED AND FIELD CONDITIONS WERE CONDUCTED TO EVALUATE THE COMPETITIVE ABILITY AND SURVIVAL OF BOTH SPECIES UNDER CURRENT AND CLIMATE CHANGE CONDITIONS. MOREOVER, WE PERFORMED AN EXPERIMENT WITH DIFFERENT WATER AVAILABILITIES TO ASSESS CELL DAMAGE AS A POTENTIAL MECHANISM INVOLVED IN THE COMPETITIVE ABILITY DEPLOYED IN BOTH SPECIES. FINALLY, WAS ASSESSED THE PLASTICITY AND BIOMASS OF BOTH SPECIES SUBJECT TO FACTORIAL ABIOTIC SCENARIOS (WATER × TEMPERATURE, AND WATER × NUTRIENTS) RANGING FROM CURRENT TO CLIMATE CHANGE CONDITION. OVERALL, RESULTS SHOWED THAT P. ANNUA HAD GREATER PHENOTYPIC PLASTICITY IN PHOTOPROTECTIVE STRATEGIES, HIGHER PERFORMANCE, AND GREATER COMPETITIVE ABILITY AND SURVIVAL THAN D. ANTARCTICA UNDER CURRENT AND CLIMATE CHANGE CONDITIONS. ALSO, CELL DAMAGE, ASSESSED BY LIPID PEROXIDATION, WAS SIGNIFICANTLY GREATER IN D. ANTARCTICA WHEN GROWN IN PRESENCE OF P. ANNUA COMPARED WHEN GROWN ALONE. FINALLY, P. ANNUA SHOWED A GREATER PLASTICITY AND BIOMASS THAN D. ANTARCTICA UNDER THE FACTORIAL ABIOTIC SCENARIOS, BEING MORE EVIDENT UNDER A CLIMATE CHANGE SCENARIO (I.E., HIGHER SOIL MOISTURE). OUR STUDY SUGGESTS THAT THE HIGH ADAPTIVE PLASTICITY AND COMPETITIVE ABILITY DEPLOYED BY P. ANNUA UNDER CURRENT AND CLIMATE CHANGE CONDITIONS ALLOWS IT TO COPE WITH HARSH ABIOTIC CONDITIONS AND COULD HELP

ECOLOGICAL RESTORATION IS THE DELIBERATE ACTION THAT SPEEDS RECOVERY FROM A DEGRADED SYSTEM BY DIRECT OR INDIRECT HUMAN INTERVENTION. XEROPHYTIC FORMATIONS ARE AMONG THE MOST DEGRADED ECOSYSTEMS WHERE LOW WATER AVAILABILITY MAKES REINTRODUCTION PLANS UNSUCCESSFUL AND EXTREMELY EXPENSIVE. ROOTS INOCULATION WITH ENDOPHYTIC FUNGI HAS BEEN REPORTED AS A SUCCESSFUL STRATEGY TO MAINTAIN OR IMPROVE THE ECOPHYSIOLOGICAL PERFORMANCE AND SURVIVAL IN DIFFERENT SPECIES OF SHRUBS AND TREES. IN HARSH ENVIRONMENTS, ENDOPHYTES HAVE BEEN SHOWN TO PROVIDE BENEFITS IN TERMS OF SURVIVAL AND GROWTH FOR THEIR ASSOCIATED VEGETATION. IN THIS STUDY, WE SHOWED THAT INOCULATION WITH ENDOPHYTES ISOLATED FROM PLANTS GROWING IN ANTARCTICA IMPROVE SURVIVAL AND WATER USE EFFICIENCY FOR IRRIGATION ON NATIVE SPECIES OF XEROPHYTIC FORMATIONS: FLOURENSIA THURIFERA, SENNA CUMINGII AND PUYA BERTERONIANA. OVERALL, THE PRESENCE OF ENDOPHYTES IMPROVED SURVIVAL OF ALL NATIVE SPECIES. FURTHERMORE, THE PRESENCE OF ENDOPHYTES IMPROVED WATER USE EFFICIENCY FOR IRRIGATION, REACHING HIGHER PERCENTAGES OF SURVIVAL IN PLANTS WITH A REDUCTION IN THE ADDED WATER. THE APPLICATION OF ANTARCTIC ENDOPHYTES COULD BE CONSIDERED A SUCCESSFUL STRATEGY FOR FUTURE PROJECTS AND REINTRODUCTION PROGRAMS IN ARID AND SEMI-ARID ZONES OF CHILE.

IN A CURRENT ARTICLE IN THE JOURNAL OF VEGETATION SCIENCE, CASANOVA-KATNY ET AL. ADDRESSED A COMMENT ABOUT AN ARTICLE BY MOLINA-MONTENEGRO ET AL., WHICH DEMONSTRATED THE CLIMATE MODIFICATION INDUCED BY THE MACROLICHEN USNEA ANTARCTICA AND ITS ROLE AS FACILITATOR. THEY PROVIDED USEFUL CORRECTIONS CONCERNING SPECIES IDENTIFICATION AND POINTED OUT SEVERAL ISSUES THAT, IN THEIR VIEW, WEAKENED OUR STUDY. THEY INDICATED THAT THE ROLE OF U. ANTARCTICA AS A FACILITATIVE SPECIES IN THE MARITIME ANTARCTICA IS MERELY PHILOSOPHICAL AND HAS NO ECOLOGICAL RELEVANCE. IN THIS COMMENTARY, WE ARGUE WHY THESE CRITIQUES ARE UNSUBSTANTIAL, AND PROVIDE EVIDENCE THAT THE MACROLICHEN CAN MODIFY THE MICROCLIMATE, AMELIORATING THE HARSH CONDITIONS PREVAILING IN ANTARCTICA, ESTABLISHING POSITIVE INTERACTIONS AND EVENTUALLY FACILITATING VASCULAR SPECIES. THUS, THE MACROLICHEN U. ANTARCTICA WOULD ACT AS A ?NURSE SPECIES?, PLAYING A KEY ROLE IN STRUCTURING THE MARITIME ANTARCTIC PLANT COMMUNITY.

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.

CLIMATIC CHANGE IS POINTED AS ONE OF THE MAJOR CHALLENGES FOR GLOBAL FOOD SECURITY. BASED ON CURRENT MODELS OF CLIMATE CHANGE, REDUCTION IN PRECIPITATIONS AND IN TURN, INCREASE IN THE SOIL SALINITY WILL BE A SHARP CONSTRAINT FOR CROPS PRODUCTIVITY WORLDWIDE. IN THIS CONTEXT, ROOT FUNGI APPEAR AS A NEW STRATEGY TO IMPROVE PLANT ECOPHYSIOLOGICAL PERFORMANCE AND CROP YIELD UNDER ABIOTIC STRESS. IN THIS STUDY, WE EVALUATED THE IMPACT OF THE TWO FUNGAL ENDOPHYTES PENICILLIUM BREVICOMPACTUM AND P. CHRYSOGENUM ISOLATED FROM ANTARCTIC PLANTS ON NUTRIENTS AND NA+ CONTENTS, NET PHOTOSYNTHESIS, WATER USE EFFICIENCY, YIELD AND SURVIVAL IN TOMATO AND LETTUCE, FACING SALINITY STRESS CONDITIONS. INOCULATION OF PLANT ROOTS WITH FUNGAL ENDOPHYTES RESULTED IN GREATER FRESH AND DRY BIOMASS PRODUCTION, AND AN ENHANCED SURVIVAL RATE UNDER SALT CONDITIONS. INOCULATION OF PLANTS WITH THE FUNGAL ENDOPHYTES WAS RELATED WITH A HIGHER UP/DOWN-REGULATION OF ION HOMEOSTASIS BY ENHANCED EXPRESSION OF THE NHX1 GENE. THE TWO ENDOPHYTES DIMINISHED THE EFFECTS OF SALT STRESS IN TOMATO AND LETTUCE, PROVOKED A HIGHER EFFICIENCY IN PHOTOSYNTHETIC ENERGY PRODUCTION AND AN IMPROVED SEQUESTRATION OF NA+ IN VACUOLES IS SUGGESTED BY THE UPREGULATING OF THE EXPRESSION OF VACUOLAR NHX1 NA+/H+ ANTIPORTERS. PROMOTING PLANT-BENEFICIAL INTERACTIONS WITH ROOT SYMBIONTS APPEARS TO BE AN ENVIRONMENTALLY FRIENDLY STRATEGY TO MITIGATE THE IMPACT OF CLIMATE CHANGE VARIABLES ON CROP PRODUCTION.

SEVERAL BACTERIA ASSOCIATED TO MACROALGAE CAN USE PHYCOCOLLOIDS AS CARBON SOURCE. ANTARCTIC BACTERIA'S HAVE PHYSIOLOGICAL CHARACTERISTICS THAT MIGHT HAVE EVOLVED TO ALLOW THE SURVIVAL AND FUNCTIONING UNDER THE HARSH CONDITIONS OF THAT ECOSYSTEM. THEREFORE, ANTARCTIC BACTERIA ISOLATED FROM ALGAE SHOULD HAVE THE ABILITY TO DEGRADE COMPLEX SUGARS AT LOWER TEMPERATURES THAN THOSE ISOLATED FROM WARMER AREAS, WHICH MAY HAVE APPLICATIONS IN THE IMPROVEMENT OF INDUSTRIAL PROCESSES THAT USES ENZYMES. THE BACTERIAL STRAIN ISOLATED FROM WRACK ALGAE, IN KING GEORGE ISLAND, ANTARCTICA, WAS IDENTIFIED AS BACILLUS ON THE BASE OF 16S RIBOSOMAL GENE ANALYSIS. THE CELL-FREE SUPERNATANT OF THE CULTURE MEDIUM SHOWED ALGINATE-LYASE AND AGARASE ACTIVITIES. SIGNIFICANT DIFFERENCES IN THE OPTIMAL TEMPERATURE TO HYDROLYZE AGAROSE AND ALGINATE WERE FOUND WITHIN A RANGE OF 4 TO 30 °C. WHILE THE AGARASE ACTIVITY WAS HIGHER AT 4° C, THE ALGINATE-LYASE ACTIVITY WAS HIGHER AT 30 °C. OUR RESULTS HAVE BIOTECHNOLOGICAL VALUE AND COULD BE USED WITH INDUSTRIAL AIMS.

FIRE IS A MAJOR DISTURBANCE AFFECTING ECOSYSTEMS WORLDWIDE. PHYLOGENETIC STUDIES HAVE SHOWN THAT THE EVOLUTION OF SEED PERSISTENCE (FIRE RESISTANCE) IS ASSOCIATED WITH FIRE FREQUENCY OR SEVERITY. HOWEVER, THE EXISTENCE OF SPECIFIC SEED TRAITS RESULTING FROM NATURAL SELECTION MEDIATED BY FIRE REMAINS A KEY QUESTION IN PLANT EVOLUTION. WE EVALUATED THE ROLE OF FIRE IN THE EVOLUTION OF SEED TRAITS FROM A MICROEVOLUTIONARY PERSPECTIVE, USING AS A STUDY SYSTEM A NATIVE FORB FROM THE CHILEAN MATORRAL, WHERE FIRE IS A NOVEL, ANTHROPOGENIC DISTURBANCE. WE SHOW THAT ANTHROPOGENIC FIRES ARE SHAPING THE EVOLUTION OF SEED TRAITS SUCH AS PUBESCENCE AND SHAPE. AMONG-POPULATION VARIATION IN SEED PUBESCENCE, SHAPE, AND PERICARP THICKNESS WAS STRONGLY ASSOCIATED WITH FIRE FREQUENCY, AND WITHIN A POPULATION, FIRE SELECTED THOSE PLANTS WITH MORE PUBESCENT SEEDS, THICKER PERICARPS, AND LESS ROUNDED SEEDS. SEED PUBESCENCE AND SHAPE WERE SHOWN TO BE HERITABLE TRAITS. OUR FINDINGS PROVIDE INSIGHTS INTO THE UNDERSTANDING OF THE EVOLUTION OF SEED TRAITS IN FIRE-PRONE ENVIRONMENTS AND DEMONSTRATE THAT HUMAN-MADE FIRES CAN BE DRIVING EVOLUTIONARY CHANGES IN PLANT SPECIES FROM ECOSYSTEMS WHERE FIRES DO NOT OCCUR NATURALLY.

AIM WE TESTED THE HYPOTHESIS THAT ANTHROPOGENIC FIRES FAVOUR THE SUCCESSFUL ESTABLISHMENT OF ALIEN ANNUAL SPECIES TO THE DETRIMENT OF NATIVES IN THE CHILEAN COASTAL MATORRAL. LOCATION VALPARAÍSO REGION, CENTRAL CHILE. METHODS WE SAMPLED SEED RAIN, SEEDBANK EMERGENCE AND ESTABLISHMENT OF SPECIES IN FOUR PAIRED BURNED AND UNBURNED AREAS AND COMPARED (USING GLMM) FIRE RESISTANCE AND PROPAGULE ARRIVAL OF ALIEN AND NATIVE SPECIES. TO ASSESS THE RELATIVE IMPORTANCE OF SEED DISPERSAL AND SEEDBANK SURVIVAL IN EXPLAINING PLANT ESTABLISHMENT AFTER FIRE, WE COMPARED SEED RAIN AND SEEDBANK STRUCTURE WITH POST-FIRE VEGETATION USING ORDINATION ANALYSES. RESULTS FIRE DID NOT CHANGE THE PROPORTION OF ALIEN SPECIES IN THE COASTAL MATORRAL. HOWEVER, FIRE INCREASED THE NUMBER OF ANNUAL SPECIES (NATIVES AND ALIENS) OF WHICH 87% WERE ALIENS. FIRE REDUCED THE ALIEN SEEDBANK AND NOT THE NATIVE SEEDBANK, BUT ALIEN SPECIES REMAINED DOMINANT IN BURNED SOIL SAMPLES (66% OF THE TOTAL SPECIES RICHNESS). SEED RAIN WAS HIGHER FOR ALIEN ANNUALS THAN FOR NATIVE ANNUALS OR PERENNIALS, THUS CONTRIBUTING TO THEIR ESTABLISHMENT AFTER FIRE. NEVERTHELESS, SEED RAIN WAS LESS IMPORTANT THAN SEEDBANK SURVIVAL IN EXPLAINING PLANT ESTABLISHMENT IN BURNED AREAS.

HIGH DIVERSIFICATION OF WOODY SEEDER LINEAGES IS CHARACTERISTIC OF THE SOUTH-WESTERN CAPE FLORISTIC REGION (CFR), SOUTH AFRICA, WHICH HAS BEEN EXPLAINED AS A CONSEQUENCE OF ITS MILD MEDITERRANEAN CLIMATE AND RELIABLE WINTER RAINFALL. SUCH CLIMATIC REGIME REDUCES THE RISK OF POST-FIRE RECRUITMENT FAILURE, ACTING AS AN ECOLOGICAL FILTER THAT FAVOURS SEEDER POPULATIONS, THUS PROMOTING GENETIC DIFFERENTIATION AND DIVERSIFICATION IN SEEDER POPULATIONS, AS PREVIOUSLY SEEN IN THE SOUTH AFRICAN HEATH ERICA COCCINEA. TO EXPLORE THIS HYPOTHESIS FURTHER, GENETIC POPULATION STRUCTURE WAS INVESTIGATED IN TWO MEDITERRANEAN ERICA SPECIES, ONE SEEDER (ERICA UMBELLATA) AND THE OTHER RESPROUTER (ERICA AUSTRALIS), USING NUCLEAR MICROSATELLITES. THESE TWO SPECIES ARE ENDEMIC TO THE WESTERN MEDITERRANEAN BASIN AND CO-OCCUR IN HEATHLANDS OF THE STRAIT OF GIBRALTAR REGION. MEAN ANNUAL RAINFALL IN THIS REGION IS SIMILAR TO THAT FROM THE SOUTH-WESTERN CFR, BUT SUMMER STRESS IS MORE MARKED AND WINTER RAINFALL IS MUCH LESS RELIABLE. CONTRARY TO WHAT WAS FOUND IN E. COCCINEA, AVERAGE GENETIC DIVERSITY LEVELS WERE CONSIDERABLY LOWER IN SEEDER POPULATIONS (E. UMBELLATA), REGARDLESS OF AN APPARENTLY HIGHER GENE FLOW AMONG THEM. NO DIFFERENCES IN GENETIC DIFFERENTIATION AMONG POPULATIONS WERE FOUND BETWEEN THE TWO SPECIES. THE OCCURRENCE OF LESS FAVOURABLE CLIMATIC CONDITIONS FOR POST-FIRE RECRUITMENT IN THE WESTERN MEDITERRANEAN COMPARED TO THE SOUTH-WESTERN CFR MAY AFFECT SEEDER POPULATIONS MORE STRONGLY THAN RESPROUTER AND MAY THUS ACCOUNT FOR LOWER LEVELS OF WITHIN-POPULATION GENETIC DIVERSITY IN THE SEEDER E. UMBELLATA. IN ADDITION, PUTATIVELY HIGHER MIGRATION RATES IN THE SEEDER E. UMBELLATA, MAY CONTRIBUTE TO REDUCE ITS POTENTIAL FOR GENETIC DIFFERENTIATION. THIS STUDY PROVIDES EVIDENCE THAT HIGH DIVERGENCE OF SEEDER POPULATIONS IS NOT A GENERAL RULE IN FIRE-PRONE, MEDITERRANEAN-TYPE ECOSYSTEMS.

BECAUSE OF ITS HARSH ENVIRONMENTAL CONDITIONS AND REMOTENESS, ANTARCTICA IS OFTEN CONSIDERED TO BE AT LOW RISK OF PLANT INVASION. HOWEVER, AN INCREASING NUMBER OF REPORTS HAVE SHOWN THE PRESENCE AND SPREAD OF NON-NATIVE PLANTS IN ANTARCTICA; IT IS THEREFORE IMPORTANT TO STUDY WHICH FACTORS CONTROL THE INVASION PROCESS IN THIS ECOSYSTEM. HERE, WE ASSESSED THE ROLE OF DIFFERENT HUMAN ACTIVITIES ON THE PRESENCE AND ABUNDANCE OF THE INVASIVE POA ANNUA. IN ADDITION, WE PERFORMED A RECIPROCAL TRANSPLANT EXPERIMENT IN THE FIELD, AND A MANIPULATIVE EXPERIMENT OF GERMINATION WITH P. ANNUA AND THE NATIVES COLOBANTHUS QUITENSIS AND DESCHAMPSIA ANTARCTICA, IN ORDER TO UNRAVEL THE EFFECTS OF PHYSICAL SOIL DISTURBANCE ON THE ESTABLISHMENT AND SURVIVAL OF P. ANNUA. WE FOUND A POSITIVE CORRELATION BETWEEN ABUNDANCE OF P. ANNUA AND LEVEL OF SOIL DISTURBANCE, AND THAT SURVIVAL OF P. ANNUA WAS 33% HIGHER IN SITES WITH DISTURBED SOIL THAN NON-DISTURBED. FINALLY, WE FOUND THAT DISTURBANCE CONDITIONS INCREASED GERMINATION FOR P. ANNUA, WHEREAS FOR NATIVE SPECIES GERMINATION IN EXPERIMENTALLY DISTURBED SOIL WAS EITHER UNCHANGED OR REDUCED COMPARED TO UNDISTURBED SOIL. OUR RESULTS INDICATE THAT HUMAN ACTIVITIES THAT MODIFY ABIOTIC SOIL CHARACTERISTICS COULD PLAY AN IMPORTANT ROLE IN THE ABUNDANCE OF THIS INVASIVE SPECIES. IF THE CURRENT PATTERNS OF HUMAN ACTIVITIES ARE MAINTAINED IN ANTARCTICA, THE ESTABLISHMENT SUCCESS AND SPREAD OF P. ANNUA COULD INCREASE, NEGATIVELY AFFECTING NATIVE FLORA.

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.

MOST CLIMATE AND ENVIRONMENTAL CHANGE MODELS PREDICT SIGNIFICANT INCREASES IN TEMPERATURE AND PRECIPITATION BY THE END OF THE 21ST CENTURY, FOR WHICH THE CURRENT FUNCTIONAL OUTPUT OF CERTAIN SYMBIOSES MAY ALSO BE ALTERED. IN THIS CONTEXT WE ADDRESS THE FOLLOWING QUESTIONS: 1) HOW THE EXPECTED CHANGES IN ABIOTIC FACTORS (TEMPERATURE, AND WATER) DIFFERENTIALLY AFFECT THE ECOPHYSIOLOGICAL PERFORMANCE OF THE PLANT COLOBANTHUS QUITENSIS? AND 2) WILL THIS ENVIRONMENTAL CHANGE INDIRECTLY AFFECT C. QUITENSIS PHOTOCHEMICAL PERFORMANCE AND BIOMASS ACCUMULATION BY MODIFYING ITS ASSOCIATION WITH FUNGAL ENDOPHYTES? PLANTS OF C. QUITENSIS FROM KING GEORGE ISLAND IN THE SOUTH SHETLAND ARCHIPELAGO (62°09? S), AND LAGOTELLERIE ISLAND IN THE ANTARCTIC PENINSULA (65°53? S) WERE PUT UNDER SIMULATED ABIOTIC CONDITIONS IN GROWTH CHAMBERS FOLLOWING PREDICTIVE MODELS OF GLOBAL CLIMATE CHANGE (GCC). THE INDIRECT EFFECT OF GCC ON THE INTERACTION BETWEEN C. QUITENSIS AND FUNGAL ENDOPHYTES WAS ASSESSED IN A FIELD EXPERIMENT CARRIED OUT IN THE ANTARCTICA, IN WHICH WE ELIMINATED ENDOPHYTES UNDER CONTEMPORARY CONDITIONS AND APPLIED EXPERIMENTAL WATERING TO SIMULATE INCREASED PRECIPITATION INPUT. WE MEASURED FOUR PROXIES OF PLANT PERFORMANCE. FIRST, WE FOUND THAT WARMING (+W) SIGNIFICANTLY INCREASED PLANT PERFORMANCE, HOWEVER ITS EFFECT TENDED TO BE LESS THAN WATERING (+W) AND COMBINED WARMING AND WATERING (+T°+W). SECOND, THE PRESENCE OF FUNGAL ENDOPHYTES IMPROVED PLANT PERFORMANCE, AND ITS EFFECT WAS SIGNIFICANTLY DECREASED UNDER EXPERIMENTAL WATERING. OUR RESULTS INDICATE THAT BOTH BIOTIC AND ABIOTIC FACTORS AFFECT ECOPHYSIOLOGICAL PERFORMANCE, AND THE DIRECTIONS OF THESE INFLUENCES WILL CHANGE WITH CLIMATE CHANGE. OUR FINDINGS PROVIDE VALUABLE INFORMATION THAT WILL HELP TO PREDICT FUTURE POPULATION SPREAD AND EVOLUTION THROUGH USING ECOLOGICAL NICHE MODELS UNDER DIFFERENT CLIMATIC SCENARIOS.

THE BIOGEOCHEMICAL CYCLES OF CARBON (C), NITROGEN (N) AND PHOSPHORUS (P) ARE INTERLINKED BY PRIMARY PRODUCTION, RESPIRATION AND DECOMPOSITION IN TERRESTRIAL ECOSYSTEMS1. IT HAS BEEN SUGGESTED THAT THE C, N AND P CYCLES COULD BECOME UNCOUPLED UNDER RAPID CLIMATE CHANGE BECAUSE OF THE DIFFERENT DEGREES OF CONTROL EXERTED ON THE SUPPLY OF THESE ELEMENTS BY BIOLOGICAL AND GEOCHEMICAL PROCESSES1,2,3,4,5. CLIMATIC CONTROLS ON BIOGEOCHEMICAL CYCLES ARE PARTICULARLY RELEVANT IN ARID, SEMI-ARID AND DRY SUB-HUMID ECOSYSTEMS (DRYLANDS) BECAUSE THEIR BIOLOGICAL ACTIVITY IS MAINLY DRIVEN BY WATER AVAILABILITY6,7,8. THE INCREASE IN ARIDITY PREDICTED FOR THE TWENTY-FIRST CENTURY IN MANY DRYLANDS WORLDWIDE9,10,11 MAY THEREFORE THREATEN THE BALANCE BETWEEN THESE CYCLES, DIFFERENTIALLY AFFECTING THE AVAILABILITY OF ESSENTIAL NUTRIENTS12,13,14. HERE WE EVALUATE HOW ARIDITY AFFECTS THE BALANCE BETWEEN C, N AND P IN SOILS COLLECTED FROM 224 DRYLAND SITES FROM ALL CONTINENTS EXCEPT ANTARCTICA. WE FIND A NEGATIVE EFFECT OF ARIDITY ON THE CONCENTRATION OF SOIL ORGANIC C AND TOTAL N, BUT A POSITIVE EFFECT ON THE CONCENTRATION OF INORGANIC P. ARIDITY IS NEGATIVELY RELATED TO PLANT COVER, WHICH MAY FAVOUR THE DOMINANCE OF PHYSICAL PROCESSES SUCH AS ROCK WEATHERING, A MAJOR SOURCE OF P TO ECOSYSTEMS, OVER BIOLOGICAL PROCESSES THAT PROVIDE MORE C AND N, SUCH AS LITTER DECOMPOSITION12,13,14. OUR FINDINGS SUGGEST THAT ANY PREDICTED INCREASE IN ARIDITY WITH CLIMATE CHANGE WILL PROBABLY REDUCE THE CONCENTRATIONS OF N AND C IN GLOBAL DRYLANDS, BUT INCREASE THAT OF P. THESE CHANGES WOULD UNCOUPLE THE C, N AND P CYCLES IN DRYLANDS AND COULD NEGATIVELY AFFECT THE PROVISION OF KEY SERVICES PROVIDED BY THESE ECOSYSTEMS.

THE BIODIVERSITY OF MOLLUSCS IS HIGHLY THREATENED IN MARINE, TERRESTRIAL AND FRESHWATER ECOSYSTEMS WORLDWIDE. THIS RESEARCH AIMED AT STUDYING THE DISTRIBUTION AND CONSERVATION STATUS OF EIGHT POORLY-KNOWN MICRO-SNAILS OF THE GENERA STEPHACHAROPA AND STEPHADISCUS IN CHILE. WE PERFORMED A COMPREHENSIVE REVIEW OF LITERATURE AND DATABASES TO DETERMINE THE OCCURRENCES OF THE SPECIES, WHICH WERE MAPPED ON VECTOR LAYERS CONTAINING PROTECTED AREAS AND HUMAN DEVELOPMENT INFRASTRUCTURE TO FIND POTENTIAL THREATS. CONSERVATION STATUS ASSESSMENT WAS PERFORMED FOLLOWING THE CRITERIA AND TOOLS IMPLEMENTED BY THE INTERNATIONAL UNION FOR THE CONSERVATION OF NATURE (IUCN) RED LIST AND NATURESERVE. WE ALSO CONDUCTED SPECIES DISTRIBUTION MODELS, BASED ON MAXIMUM ENTROPY, TO IDENTIFY AREAS THAT SHOULD BE PRIORITISED FOR CONSERVATION. TWO SPECIES MEET THE CRITERIA FOR IUCN LISTING AS CRITICALLY ENDANGERED (CR), FOUR ENDANGERED (EN), ONE VULNERABLE (VU) AND ONE LEAST CONCERN (LC). THIS CLASSIFICATION IS RATHER COINCIDENT WITH EQUIVALENT CATEGORIES OBTAINED UNDER THE NATURESERVE STANDARD, IN WHICH TWO SPECIES WERE RANKED AS CRITICALLY IMPERILED (N1), FIVE IMPERILED (N2) AND ONE VULNERABLE (N3). WE FOUND THAT STEPHACHAROPA PAPOSENSIS IS THE MOST AT-RISK SPECIES, WITH ONLY ONE OCCURRENCE NOT INCLUDED IN A PROTECTED AREA, FOLLOWED BY STEPHADISCUS STUARDOI, WITH TWO OCCURRENCES, ONE OF THEM WITHIN A PROTECTED AREA. STEPHADISCUS LYRATUS WAS THE SPECIES WITH THE GREATEST GEOGRAPHIC RANGE, ACCOUNTING FOR 17 OCCURRENCES, SEVEN MATCHING A PROTECTED AREA. WE FOUND WIDER POTENTIAL RANGES IN MODELLED SPECIES THAT MAY BE USEFUL FOR PRIORITISING CONSERVATION MEASURES. CONSIDERING DISTRIBUTIONAL DATA, PROTECTED AREAS AND MORE THAN 20 PLAUSIBLE THREATS IDENTIFIED, WE PROPOSE POTENTIAL IN SITU AND EX SITU CONSERVATION ACTIONS TO PROTECT THESE NEGLECTED MICRO-SNAILS.

THE GENUS RADIODISCUS INCLUDES MINUTE TERRESTRIAL SNAILS OCCURRING THROUGHOUT THE AMERICAN CONTINENT. WE ASSESSED THE CONSERVATION STATUS OF EIGHT POORLY KNOWN CHILEAN RADIODISCUS SPECIES USING THE INTERNATIONAL UNION FOR CONSERVATION OF NATURE (IUCN) AND NATURESERVE CATEGORIES AND CRITERIA. UNDER THE IUCN GUIDELINES THE SPECIES WERE ASSESSED USING THE CRITERION B OF GEOGRAPHIC RANGE, WHICH CONSIDERS THE EXTENT OF OCCURRENCE (EOO) AND AREA OF OCCUPANCY (AOO) AS SUBCRITERIA. FOR NATURESERVE WE USED THESE TWO PARAMETERS PLUS THE NUMBER OF OCCURRENCES, ECOLOGICAL VIABILITY, AND THREATS. CONSIDERING SPECIES RARITY AND POSSIBLE SAMPLING BIAS, WE ALSO USED ECOLOGICAL NICHE MODELING TO DETERMINE CLIMATE AND ENVIRONMENTAL TOLERANCES AND PREDICT POTENTIAL SPECIES DISTRIBUTIONS ANALYZING BIOCLIMATIC AND GEOGRAPHICAL LAYERS. RADIODISCUS AUSTRALIS, R. COARCTATUS AND R. QUILLAJICOLA WERE LISTED AS CRITICALLY ENDANGERED BY IUCN AND NATURESERVE STANDARDS; R. COPPINGERI, R. FLAMMULATUS, R. MAGELLANICUS AND R. VILLARRICENSIS AS ENDANGERED BY BOTH METHODS; WHILE R. RIOCHICOENSIS AS ENDANGERED BY IUCN STANDARDS AND VULNERABLE BY NATURESERVE STANDARDS. NICHE MODELING RESULTS INDICATED THAT RADIODISCUS SPECIES RESPOND TO DIFFERENT ENVIRONMENTAL CONDITIONS AND THAT THE PREDICTED DISTRIBUTION AREAS CONTAIN SUITABLE HABITATS BEYOND THE CURRENT RANGES, WHICH MAY BE HELPFUL FOR FUTURE MANAGEMENT PLANS. NATURE-BASED SPORT TOURISM, FORESTRY ACTIVITIES, URBANIZATION, ROADS, POLLUTION, MINING, FOREST FIRES, LIVESTOCK, VOLCANISM, TSUNAMIS, SOIL EROSION AND INTRODUCED SPECIES ARE AMONG THE MAJOR THREATS AFFECTING THESE SNAILS. BASED ON THE LOW NUMBER OF OCCURRENCES AND THE THREATS IDENTIFIED, THE MOST AT-RISK SPECIES ARE R. COARCTATUS AND R. QUILLAJICOLA (ONE RECORD), R. AUSTRALIS (TWO RECORDS) AND R. VILLARRICENSIS (THREE RECORDS); THE LATTER TWO LACKING OCCURRENCES WITHIN PROTECTED AREAS. COMPILING OUR FINDINGS, WE PROPOSE A LIST OF ACTIONS TO PRESERVE CHILEAN RADIODISCUS SPECIES.