Understanding lineage divergence is crucial for uncovering cryptic biodiversity. Adaptive divergence, geographic isolation and life-history traits drive speciation in heterogeneous environments. The gentoo penguin complex (Pygoscelis spp.), historically treated as a single species, provides an ideal system to examine divergence across its full distribution. Here, we show the existence of four divergent evolutionary lineages (northern, southern, southeastern, and eastern), supported by phylogenomic and lineage-specific selective pressures, despite ancestral gene flow. South Georgia and Macquarie individuals whose status has been debated, were included. Genomic scans reveal lineage-specific signals of positive selection in genes related to thermoregulation, oxygen transport, metabolism, and skeletal development, consistent with ecological and morphological differentiation across the Antarctic Polar Front. Future niche projections indicate severe habitat losses for three lineages, whereas the southern gentoo may expand its range. We propose a taxonomic revision recognizing four distinct gentoo penguin species, including Pygoscelis kerguelensis sp. nov., with important conservation implications.

Mediterranean ecosystems, one of the most significant global hotspots of biodiversity, are threatened by invasive weeds. Although endomicrobiomes - the vast array of microbes colonising living plant tissues - are known to affect plant fitness, their contribution to weed invasiveness remains virtually unknown. Here, we experimentally assess the role of the endomicrobiome in the invasiveness of Taraxacum officinale (common dandelion), a widespread weed in Mediterranean ecosystems worldwide. In a culling experiment across five generations, we compare the fitness of T. officinale from these ecosystems on five continents grown with intact or reduced native seed-borne endomicrobiomes. Additionally, we report a competition experiment with F1 and F5 individuals assessing their impacts on native local Asteraceae species. We found that T. officinale individuals harboring intact endomicrobiomes show faster and more favorable trait development compared with individuals with reduced endomicrobiomes. Enhanced competitiveness of endomicrobiome-colonised T. officinale plants with local Asteraceae species is apparently caused by increased synthesis of allelochemicals in shoots and rhizosphere soil, with gene expression analyses also showing the endomicrobiome to affect the expression by T. officinale of stress response and RNA-directed DNA methylation genes. Our findings provide insights into the mechanisms underlying weed invasiveness in Mediterranean ecosystems.

Antarctica harbors many distinctive features of life, yet much about the diversity and functioning of Antarctica’s life remains unknown. Evolutionary histories and functional ecology are well understood only for vertebrates, whereas research on invertebrates is largely limited to species descriptions and some studies on environmental tolerances. Knowledge on Antarctic vegetation cover showcases the challenges of characterizing population trends for most groups. Recent community-level microbial studies have provided insights into the functioning of life at its limits. Overall, biotic interactions remain largely unknown across all groups, restricted to basic information on trophic level placement. Insufficient knowledge of many groups limits the understanding of ecological processes on the continent. Remedies for the current situation rely on identifying the caveats of each ecological discipline and finding targeted solutions. Such precise delimitation of knowledge gaps will enable a more aware, representative, and strategic systematic conservation planning of Antarctica.

Genomic adaptation and introgression can occur during the speciation process, enabling species to diverge in their frequencies of adaptive alleles or acquire new alleles that may promote adaptation to environmental changes. There is limited information on introgression in organisms from extreme environments and their responses to climate change. To address these questions, we focused on the 3 southern skua species, selected for their widespread distribution across the Southern Hemisphere and their complex history of speciation and introgression events. Our genomic data reveal that these skuas underwent diversification around the Penultimate Glacial Period, followed by subsequent demographic expansion. We identified a geographic region of introgression among species that followed a directional pattern sourced from the Antarctic continent, South America, and east to west in subantarctic islands, all converging towards the Antarctic Peninsula. The 3 skua species and admixed individuals exhibited a unique pattern of putative genes under selection, allowing adaptation to extreme conditions. Individuals with a higher proportion of Brown Skua ancestry showed signs of selection on genes related to reproductive isolation, while admixed individuals with a higher proportion of South Polar Skua ancestry displayed patterns resembling those of the South Polar Skua. Introgression may be a key mechanism of adaptation for many species that may help buffer against the ongoing climate change.

Antarctica, which has always been of great interest to researchers worldwide, is currently attracting considerable attention owing to climate change and other topics. In this context, bibliometric analysis allows the identification of hot topics, scientific productivity, cooperation, research gaps and strategic areas of potential interest. We conducted a bibliometric study to evaluate the global production of Antarctic research between 1980 and 2023 and analysed Spanish National Antarctic Programme (NAP) production as a case study. Scientific publications were reviewed and classified based on their main themes, key word co-occurrence and international collaborations. We found that scientific production worldwide and in the Spanish NAP has progressively increased since 1980. Globally, the main areas of research are the geosciences, oceanography and atmospheric sciences. However, the Spanish NAP, which reported 2287 publications, has focused more on the geosciences and ecology. Spanish Antarctic researchers have mainly collaborated with researchers from the USA, the UK, Germany and Italy. Our research highlights the importance of strengthening research plans to diversify and facilitate international collaboration, promoting a more interdisciplinary approach to address the current and future challenges identified by the scientific community. In this context, specific opportunities for developing a Spanish NAP strategic plan are discussed.

Climate change is projected to substantially alter the Southern Ocean’s physical and chemical properties, thereby impacting its marine ecosystems and species, particularly those in Antarctic and sub-Antarctic regions. This study focuses on Neobuccinum eatoni, a polar marine ‘true whelk’ endemic to these regions, utilizing 166 spatially independent occurrence data records to model potential distribution shifts under future climate scenarios. Employing Species Distribution Models (SDMs) on spatially cross-validated occurrences, we achieved high predictive accuracy, identifying "sea water salinity range" at mean bottom depth as the most significant predictor of habitat preferences. Additionally, dissolved iron (minimum), ocean temperature (range), and pH (long-term maximum) emerged as critical factors influencing the species’ modeled distribution. By 2050, future projections under the SSP2-4.5 scenario predict an eastward expansion, particularly in the Antarctic Peninsula, the Scotia Arc and the Weddell Sea, with an expansion in the latter region also predicted under the SSP5-8.5 scenario. However, in both scenarios, a reduction in habitat suitability is expected in certain sectors around the Antarctic continent and the Kerguelen Archipelago. By 2100, under the moderate emissions scenario (SSP2-4.5), the species is projected to move to deeper areas and lower latitudes, with notable expansions in the Weddell Sea and in the Southern Ocean surrounding the Kerguelen Archipelago. However, under the SSP5-8.5 scenario, expansion is projected in the Weddell Sea and reductions in Antarctic and subantarctic regions. This study highlights the critical influence of changing salinity on N. eatoni’s distribution, predicting a significant habitat reduction under high CO2 emissions scenarios (SSP5-8.5). The findings underscore the urgent need for focused research on the vulnerability of endemic marine invertebrates to develop effective conservation strategies in the face of rapid climatic changes.

Aims Cold environments, such as polar systems, are highly vulnerable to global change drivers such as climate change and invasive species. Therefore, it is essential to assess what drives the diversity of native and invasive species in these systems. LocationWe investigated what drives native and alien plant species richness on sub-Antarctic Marion Island and determined the scale-dependence of these drivers. Methods Native and alien plant species richness was surveyed at "small" (1 m2) and "large" (9 m2) sampling grains. Difference in richness between the two sampling grains was calculated to assess how local turnover contributes to species assemblage. The factors driving richness at both grains, and the differences in richness between the two grains, were analysed using simultaneous auto-regressive models. Drivers related to energy and environmental heterogeneity were correlated with native richness, whilst drivers related to productivity were related to alien richness. Results Biotic interactions with a cushion plant facilitated native richness, but restricted alien richness at low elevations. Further, some drivers of richness depended on spatial grain. Native richness was positively related to northness at large, but not small grain size, suggesting that higher northness increases local turnover at a grain size > 1 m2. On the other hand, topographical wetness index (TWI) boosted native richness at small but not large grains, implying that competition for water limits coexistence at low TWI (i.e., low moisture availability) only at small grain. Differences in native species richness between large and small grain sizes were more pronounced at low elevations, suggesting higher compositional heterogeneity at low altitudes. Conclusions Our study highlights that drivers of plant species richness in a polar ecosystem differ between native and alien plant species. Additionally, the effects of some drivers on richness differ between sampling grains, and considering these differences provides insight into drivers of local patterns of species assemblage.

In temperate grasslands, periodic or seasonal burning is considered critical for maintaining plant diversity and ecosystems. Under global change scenarios such as warmer and wetter climates and increasing alien invasions, fire is predicted to increase in intensity in many ecosystems. While the effects of fire on many terrestrial habitats (e.g., grassland, forest) have been extensively studied, less attention has been paid to the effects of fire intensity on the underlying soil microbiome. In this study, we used metagenomics, via 16S rRNA amplicon sequencing, coupled with functional assays and thermal profiling, to investigate the effects of increased fire intensity on the short- and medium-term composition and functionality of grassland soil microbiomes. The results indicated that an increase in fire calorific output had a short-term negative effect on soil microbial activity in grassland plots supplemented with plant biomass to simulate increases in fire intensity. In turn, the taxonomic profiling of soil microbial communities revealed that these plots were enriched in fast-growing bacterial taxa 4 weeks after the fire event when compared to plots without biomass supplementation. This suggests that increased fire intensity exerts a medium-term effect on the recovery of grassland soil microbiomes.

Rapid environmental changes in Subantarctic and Antarctic regions pose significant threats to fauna dependent on interconnected terrestrial and marine ecosystems. Here, we investigate the ecological niches and potential distribution dynamics of two sister species of sheathbills, Chionis albus and C. minor, which range from South America to the Antarctic Peninsula (C. albus) or are restricted to some Subantarctic islands (C. minor). Ecological niches were estimated in environmental space through a principal component analysis-based modelling approach, while species distribution models provided geographically explicit projections; together, these complementary methods allowed us to assess niche dynamics. Projections for 2070 under two climate scenarios (SSP1-2.6 and SSP5-8.5) show that C. albus occupies a broader ecological niche, with high stability in both terrestrial (99%) and marine (94-95%) habitats, and when combined, 95% of its range remains stable with low extinction (≤1%) and moderate expansion (4.2-4.3%). In contrast, C. minor shows lower stability (83-96%), higher extinction potential (up to 6%) and greater expansion variation (2.8-13.6%). However, when habitats are combined, extinction zones decrease to near zero under both scenarios. Our findings underscore the vulnerability of island species to environment-driven range shifts and show that integrating terrestrial and marine habitats provides more conservative and robust risk projections.

Temperature is a primary driver to define the ecophysiological activity and performance of ectotherms. Thus, thermal tolerance limits have a profound effect in determining geographic ranges. In regions with extreme cold temperatures, lower thermal limits of species are a key physiological trait for survival. Moreover, thermal niche breadth also plays an important role in allowing organisms to withstand climatic variability and confers species with broader potential to establish in new regions. Here we study the evolution of thermal tolerance limits among Collembola (Arthropoda) and explore how they are affected by the colonization of polar environments. In addition, we test the hypothesis that globally invasive species are more eurythermal than non‐invasive ones. Critical thermal limits (CT min and CT max ), classic measurements of thermal tolerance, were compiled from the literature and complemented with experimental assays for springtail species. Genetic data of the mitochondrial gene cytochrome oxidase subunit 1 (COI) was used to assemble a phylogeny. Our results show that polar springtails have lower CT min and lower CT max compared to species from temperate and tropical regions, consistent with the Polar pressure hypothesis. We found no phylogenetic signal for CT max , but low values of phylogenetic signal for CT min . Globally invasive species do not have significantly broader thermal tolerance breadth (CT range ) than non‐invasive ones, thus not supporting the predictions of the Eurythermality hypothesis. We conclude that polar springtails have evolved their thermal niches in order to adapt to extremely cold environments, which has led to decreasing both upper and lower thermal tolerance limits.

The relative importance of genetic drift and local adaptation in facilitating speciation remains unclear. This is particularly true for seabirds, which can disperse over large geographic distances, providing opportunities for intermittent gene flow among distant colonies that span the temperature and salinity gradients of the oceans. Here, we delve into the genomic basis of adaptation and speciation of banded penguins, Galápagos (Spheniscus mendiculus), Humboldt (Spheniscus humboldti), Magellanic (Spheniscus magellanicus), and African penguins (Spheniscus demersus), by analyzing 114 genomes from the main 16 breeding colonies. We aim to identify the molecular mechanism and genomic adaptive traits that have facilitated their diversifications. Through positive selection and gene family expansion analyses, we identified candidate genes that may be related to reproductive isolation processes mediated by ecological thermal niche divergence. We recover signals of positive selection on key loci associated with spermatogenesis, especially during the recent peripatric divergence of the Galápagos penguin from the Humboldt penguin. High temperatures in tropical habitats may have favored selection on loci associated with spermatogenesis to maintain sperm viability, leading to reproductive isolation among young species. Our results suggest that genome-wide selection on loci associated with molecular pathways that underpin thermoregulation, osmoregulation, hypoxia, and social behavior appears to have been crucial in local adaptation of banded penguins. Overall, these results contribute to our understanding of how the complexity of biotic, but especially abiotic, factors, along with the high dispersal capabilities of these marine species, may promote both neutral and adaptive lineage divergence even in the presence of gene flow.

The increased availability of quality genomic data has greatly improved the scope and resolution of our understanding of the recent evolutionary history of wild species adapted to extreme environments and their susceptibility to anthropogenic impacts. The guanaco (Lama guanicoe), the largest wild ungulate in South America, is a good example. The guanaco is well adapted to a wide range of habitats, including the Sechura Desert, the high Andes Mountains to the north, and the extreme temperatures and conditions of Navarino Island to the south. Guanacos also have a long history of overexploitation by humans. To assess the evolutionary impact of these challenging habitats on the genomic diversity, we analyzed 38 genomes (∼10 to 16×) throughout their extensive latitudinal distribution from the Sechura and Atacama Desert to southward into Tierra del Fuego Island. These included analyses of patterns of unique differentiation in the north and geographic region further south with admixture among L. g. cacsilensis and L. g. guanicoe. Our findings provide new insights on the divergence of the subspecies ∼800,000 yr BP and document two divergent demographic trajectories and to the initial expansion of guanaco into the more southern portions of the Atacama Desert. Patagonian guanacos have experienced contemporary reductions in effective population sizes, likely the consequence of anthropogenic impacts. The lowest levels of genetic diversity corresponded to their northern and western limits of distribution and some varying degrees of genetic differentiation. Adaptive genomic diversity was strongly linked with environmental variables and was linked with colonization toward the south followed by adaptation.

The extreme low humidity and temperatures in Antarctica make it one of the harsher areas for life on our planet. In a global change context, environmental barriers that prevented the arrival of alien species in Antarctica are weakening. Deception Island, one of the four active volcanoes of Antarctica, is especially vulnerable to the impacts of alien species. Geothermal areas (GA) in this Island offer unique microclimatic conditions that could differentially affect native and alien soil arthropods. Here we explore the desiccation tolerance of a native (Cryptopygus antarcticus) and an alien (Proisotoma minuta) springtail (Collembola) species to these extreme environmental conditions. GA and non-geothermal areas (NGA) were selected to evaluate intra- and interspecific variation in desiccation tolerance. Populations of P. minuta from GA had greater desiccation tolerance than populations from NGA. However, desiccation tolerance of C. antarcticus did not differ between GA and NGA. This native species had greater desiccation tolerance than the alien P. minuta, but also greater body size. Our findings show that the alien P. minuta responds differently to environmental conditions than the native C. antarcticus. Furthermore, body size may influence desiccation tolerance in these two springtail species.

Background Incomplete species inventories for Antarctica represent a key challenge for comprehensive ecological research and conservation in the region. Additionally, data required to understand population dynamics, rates of evolution, spatial ranges, functional traits, physiological tolerances and species interactions, all of which are fundamental to disentangle the different functional elements of Antarctic biodiversity, are mostly missing. However, much of the fauna, flora and microbiota in the emerged ice -free land of the continent have an uncertain presence and/or unresolved status, with entire biodiversity compendia of prokaryotic groups (e.g. bacteria) being missing. All the available biodiversity information requires consolidation, cross -validation, re -assessment and steady systematic inclusion in order to create a robust catalogue of biodiversity for the continent. New information We compiled, completed and revised eukaryotic species inventories present in terrestrial and freshwater ecosystems in Antarctica in a new living database: terrANTALife (version 1.0). The database includes the first integration in a compendium for many groups of eukaryotic microorganisms. We also introduce a first catalogue of amplicon sequence variants (ASVs) of prokaryotic biodiversity. Available compendia and literature to date were searched for Antarctic terrestrial and freshwater species, integrated, taxonomically harmonised and curated by experts to create comprehensive checklists of Antarctic organisms. The final inventories comprises 470 animal species (including vertebrates, freeliving invertebrates and parasites), 306 plants (including all Viridiplantae: embryophytes and green algae), 997 fungal species and 434 protists (sensu lato). We also provide a first account for many groups of microorganisms, including non-lichenised fungi and multiple groups of eukaryotic unicellular species (Stramenophila, Alveolata and Rhizaria (SAR), Chromists and Amoeba), jointly referred to as "protists". In addition, we identify 1753 bacterial (obtained from 348117 ASVs) and 34 archaeal genera (from 1848 ASVs), as well as, at least, 14 virus families. We formulate a basic tree of life in Antarctica with the main lineages listed in the region and their "known-accepted-species" numbers.

The terrestrial high-Arctic has, so far, escaped the worst impacts of non-native plant establishment. However, increasing human activity and changing climate raise the risk of introductions and establishment, respectively. The lack of biosecurity in the terrestrial Arctic is thus of concern. To facilitate the development of biosecurity measures on the rapidly warming and highly trafficked archipelago of Svalbard, we generated ecological niche models to map the bioclimatic niche potential of 27 non-native established or door-knocker vascular plant species across Svalbard, identify species with a high risk of widespread occupancy, and locate hotspots of potential current and future invasions. Under the current climate the three species with the highest threat in terms of broad potential area of occupancy and known invasion potential were Deschampsia cespitosa, Ranunculus subborealis subsp. villosus and Saussurea alpina. However, under future climate, most of the considered species have potentially wide distributions across the archipelago. Remote eastern islands were a hotspot region for broader potential establishment of non-native species under the current climate. Our results suggest that many non-native plant species have a broader macroclimatic niche on Svalbard than they currently occupy, and that other factors probably limit both dispersal and establishment outside their current localised distributions. Environmental management on Svalbard has a limited window of opportunity to act early in containing and preventing the spread of non-native plant species beyond the few settlements where they currently exist. Moreover, preventing introductions and establishments on the remote and rarely visited islands of Edgeøya, Barentsøya and Bjørnøya could be also a priority action to safeguard sanctuaries of the archipelago’s natural ecosystems.

Grasses (Family Poaceae) are among the most successful invasive plants in the world. Here we evaluate phylogenetic and biogeographic patterns of emergence of naturalized and invasive species among grasses globally. In our data, circa 19% of the grasses are currently catalogued as invasive and almost 38% are listed as naturalized; these are among the highest ratios for single families of organisms. Remarkably, most tribes of grasses contain numerous naturalized and invasive species, suggesting that the invasion success is rooted broadly in ancestral traits in the Poaceae. Moreover, the probability of invasiveness is positively related to the diversification rates in the family also suggesting a link with recent radiation events. The phylogenetic distribution of the invasive condition is neither strongly conserved nor purely random. Phylogenetic clumping levels also vary between Poaceae subclades. We postulate that this diffuse clumping could be partially attributed to the expression of labile traits that contribute to species invasiveness. In addition, floristic regions (biomes and biogeographic realms) have different proportions of invasive species, with the temperate Palearctic region having the highest ratio of invasive vs. non-invasive species. The phylodiversity of aliens across regions is also variable in space. Comparison of alien phylodiversity levels across biogeographic realms and biomes reveals regions producing highly restricted invasive lineages and others where the diversity of aliens exported is no different from global mean diversity levels in grasses. Elucidating the evolutionary patterns and drivers of invasiveness is useful for understanding and managing invasions, with the low phylogenetic structure of alien grasses warning of their overall high invasiveness potential.

Environmental and biotic factors drive species richness patterns, but the nature of this relationship can vary with sampling grain. Understanding the scale-dependent effects of these factors is crucial for interpreting species richness patterns in ecosystems experiencing rapid environmental change. We investigated the effects of local environmental drivers on plant species richness at small (1 x 1 m) and large (3 x 3 m) sampling grains, and the factors correlated with differences in richness between the two grains, on a sub-Antarctic island. Broadly, richness was higher in warmer (i.e., lower altitude, north-facing) and wetter (i.e., higher topographic wetness index, lower distance from drainage line) sites, and in more topographically heterogenous (i.e., steeper slopes) sites. Additionally, there was some evidence of competition with a keystone plant limiting species richness, though this was only evident at low elevations. However, the effects of several drivers on richness depended on spatial grain. Differences in species richness between large and small grain sizes were more pronounced at low elevations, indicating that there is more compositional heterogeneity at low altitudes at both grains. Richness was positively related to northness at large grain size but not at small grain size, suggesting that higher northness increases local turnover at a grain size > 1 m2. On the other hand, TWI boosted richness at small but not large grains, implying that competition limited coexistence at low TWI, and that higher TWI only resulted in more species coexisting at a grain of 1 m2, while having no effect on richness at large grains. Our study therefore highlights that drivers of plant species richness can vary with sampling grain, suggesting that environmental effects on local species turnover affect richness patterns at different grains. Assessing how the influence of such drivers differ with grain size provides insight into local patterns of species assemblage.