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The Ediacaran Period is of interest for the emergence of multicellular life, one or more glaciations, and the occurrence of the largest δ13C excursion in Earth history (the Shuram). The Ediacaran stratigraphic succession in the Flinders Ranges of South Australia is distinctive also for well‐exposed outcrop examples of palaeocanyons and salt diapirs. We present data placing a level of salt‐sheet breakout during deposition of the Wonoka Formation, within the time span of the Shuram, and at a datum indistinguishable from the canyon incision level. We hypothesize that canyon incision and salt breakout were triggered by subaerial erosion and non‐deposition associated with sea‐level drawdown in a temporarily isolated embayment. This mechanism provides support for the idea that the palaeocanyons were fluvially incised, and imposes a new constraint on the palaeoenvironmental setting of Australia at the time of the Shuram and the Ediacara fauna. [ABSTRACT FROM AUTHOR]

The sedimentary infill of the Quibas karstic site (Early Pleistocene, southern Spain) represents the only continuous succession with remains of continental vertebrates in Europe from pre-Jaramillo to post-Jaramillo age. The Quibas site, with a significant paleontological record, is dated between 1.1 and 0.9 Ma and offers a unique opportunity to carry out a paleoclimatic reconstruction of the time period immediately after the arrival of the first humans to western Europe. For this reason, defining the dominant sedimentary processes in the different stratigraphic units and the associated paleoenvironment is essential. The Quibas site is made up of two karstic features with two stratigraphic sequences: Quibas-Cueva, containing six lithostratigraphic units, and Quibas-Sima, which contains seven lithostratigraphic units. The detailed description and analyses of the stratigraphic sections have allowed the characterization of various autochthonous and allochthonous facies of cave deposits. Paleoclimatic proxies, inferred from sedimentological analyses, reveal a record of several alternating humid and arid phases resulting from the Early Pleistocene glacial-interglacial cycles, allowing correlation to the marine oxygen isotope record. The lowermost units (pre-Jaramillo) were deposited during a long-lasting interglacial, correlated to MIS 33–31. It was followed by an increase in aridity in the intermediate units of Quibas-Sima and uppermost unit of Quibas-Cueva (Jaramillo), revealing the beginning of a glacial period at the start of the Jaramillo subchron (1 Ma), which can be correlated to MIS 30. The upper Jaramillo and post-Jaramillo units suggest these were deposited in alternating periods of aridity and humid conditions, although less humid than the pre-Jaramillo period, probably representing the MIS 29 interglacial, the MIS 28 glacial and the MIS 27 interglacial. [ABSTRACT FROM AUTHOR]

Based on the distribution of 275 species of ants native to the Iberian Peninsula (IP), we identified areas of endemism (AE) within its geographical limits and present a biogeographic regionalization using two complementary methods and two types of operational geographical units. For endemicity analysis (EA), we used a 100 km2 grid cell, and for parsimony analysis of endemicity (PAE), we used hydrological basins as natural units. The EA revealed twelve areas of endemism that were grouped into five consensus areas. These are the Northeastern area, South plateau, Guadalquivir Valley, Baetic System, and Iberian Peninsula (whole). PAE resulted in a cladogram that classified hydrological basins into at least two successively nested subsets: an Atlantic group that is more related to northern European fauna and an Iberian subset that is well supported by synapomorphies. The Iberian subset was differentiated into four main areas: (a) a Northeastern area formed by the Pyrenees and the Catalan Coastal Range, (b) a mainland area containing the Central System and Guadiana and Tajo valleys, (c) a Southern area consisting of the Guadalquivir Valley and the Baetic System, and (d) a Northern coastal area. The results showed congruence between the two methods since many of the synapomorphies are shared among the diagnostic and IP endemic species of the EA. Both EA and PAE showed the relevance of the heterogeneous peninsular orography that combines mountainous regions with valleys and plateaus, which have acted as historical barriers or corridors. The presence of numerous endemic species, particularly in the southern third of the IP, suggests that several Iberian refuges for ants originated during glacial periods. These areas constitute priority sites for the conservation of ants in particular and biodiversity in general on the IP and allow further research about the processes that generated these distributional patterns. [ABSTRACT FROM AUTHOR]

This research was carried out in north-central Poland, which was occupied by the ice sheet of the Saalian (Marine Isotope Stage [MIS] 6) and Upper Stadial of the Weichselian (MIS 2) glaciation. The application of the anisotropy of magnetic susceptibility (AMS) method supported by a digital elevation model (DEM) analysis of the orientation of glacial landforms allowed for the reconstruction of ice-sheet extent and ice movement directions of these two Pleistocene glaciations. The research used an innovative method of collecting AMS till samples from the glacial plateau areas. Based on the research, it was found that during the general recession of the ice sheet of the Saalian glaciation, a previously undescribed glacial transgression occurred, characterized by a different direction of ice-sheet movement. On the basis of detailed geomorphological studies of the area of terminal moraines, previously described in fragments, the maximum extent of the ice sheet during the Weichselian glaciation was clarified. The recession of the ice sheet of the Weichselian glaciation from the area of north-central Poland took place in four regressive or transgressive–regressive stages with variable directions of ice-sheet movement. The results obtained indicate the great potential of the AMS method in paleoenvironmental studies of glaciated areas. [ABSTRACT FROM AUTHOR]

The high-resolution pollen record retrieved from dated sediments of the Khanka Depression has made it possible for the first time to reconstruct evolution of vegetation in the south of the Russian Far East that occurred during one of the coldest phase of MIS 2 – the Younger Dryas. The results of the spore-pollen analysis have shown that worsening of climate conditions between 18 200 and 15 500 cal yr BP that occurred after the first, slight warming during MIS 2, caused boreal flora plants, dominating in the south of Russian Far East, to spread again in the drier and colder climate comparable to the Gydan Stage of the Sartan Glaciation. Their distribution areas in the cold climate that differed significantly from the modern ones again started to shift to the south due to increasing cooling. The spruce and small-leaved forests, sparse larch and dwarf birch, alder and dwarf pine forests, and also sphagnum bogs dominated in the ecosystems of the region. [ABSTRACT FROM AUTHOR]

Habitat fragmentation can facilitate local adaptation of species to heterogeneous environments and affect population demographic history. To understand the factors influencing evolutionary dynamics, such as climatic fluctuations and complex geomorphological features, we used 18 chloroplast microsatellites, 15 nuclear microsatellites, three chloroplast fragments, and two nuclear regions to explore the genetic structure and phylogeographical history of Pseudotaxus chienii. Furthermore, its current and past distributions were constructed based on ecological niche modelling. Moderate to high levels of genetic diversity were found at the species level. Precipitation was a decisive factor influencing the genetic structure of P. chienii. In addition, local adaptation to heterogeneous environments also contributed to maintain the fragmented distribution. Finally, incomplete lineage sorting led to the cyto-nuclear discordance. Overall, we show that pre-Quaternary and Quaternary climatic fluctuations and restricted gene flow exerted significant effects on the formation and maintenance of the fragmented distribution of P. chienii. The study provides new insights into the evolutionary history of plants in subtropical China. [ABSTRACT FROM AUTHOR]

Phylogeography bears an important part in ecology and evolution. However, current phylogeographic studies are largely constrained by limited numbers of individual samples. Using an environmental DNA (eDNA) assay for phylogeographic analyses, this study provides detailed information regarding the history of Siberian stone loach Barbatula toni, a primary freshwater fish across the whole range of Hokkaido, Japan. Based on an eDNA metabarcoding on 293 river water samples, we detected eDNA from B. toni in 189 rivers. A total of 51 samples, representing the entire island, were then selected from the B. toni eDNA‐positive sample set for the subsequent analyses. To elucidate the phylogeographic structure of B. toni, newly developed eDNA metabarcoding primers (Barba‐cytb‐F/R) were applied to these samples, specifically targeting their haplotypic variation in cytochrome b. After a bioinformatic processing to mitigate haplotypic false positives, a total of 50 eDNA haplotypes were identified. Two regionally restricted, genetically distinct lineages of the species were revealed as a result of phylogeographic analyses on the haplotypes and tissue‐derived DNA from B. toni. According to a molecular clock analysis, they have been genetically isolated for at least 1.5 million years, suggesting their ancient origin and colonisation of Hokkaido, presumably in the glacial periods. These results demonstrate how freshwater fishes can alter their distributions over evolutionary timescales and how eDNA assay can deepen our understanding of phylogeography. [ABSTRACT FROM AUTHOR]

Aim: The continental island system comprising Sakhalin, Hokkaido and the southern Kuril Islands (SHSK) in northeastern Asia serves as one of the southernmost habitats for many boreal and arctic organisms, with colonization via land bridges formed during glacial periods. To understand the impacts of past land‐bridge formation under Quaternary climate changes across SHSK, we investigated the demographic history of forest‐dwelling marten species. Location: Sakhalin, Hokkaido and the southern Kuril Islands in northeastern Asia. Taxon: Sable, Martes zibellina (Carnivora, Mustelidae). Methods: We employed multiplexed inter‐simple sequence repeat genotyping by sequencing (MIG‐seq) to obtain genome‐wide single nucleotide polymorphisms (SNPs). We tested possible scenarios of colonization and diversification for SHSK sables using several population genetics approaches including clustering analysis, population tree estimation and approximate Bayesian computation modelling. We also examined haplotype diversity for the mitochondrial ND2 gene. Results: The genetic diversity of the island populations and their affinity for continental populations were found to be higher in the order Sakhalin > Hokkaido > Iturup in both nuclear SNP and mitochondrial DNA analyses. Demographic analyses indicated that the sable migrated repeatedly from the continent, particularly to the neighbouring Sakhalin Island. However, only an earlier colonized lineage has persisted on marginal Iturup Island since the Middle Pleistocene. The stronger effects of repeated migrations and/or isolation influenced by the distance to the continent have shaped the contemporary genetic diversity and differentiation of sable populations in SHSK. Main Conclusions: Genome‐wide and comprehensive sampling approaches demonstrated that the forest‐dwelling sable had long‐term persistence with partial admixture of multiple lineages in SHSK, suggesting the existence of forest corridors and refugia on the islands during the last several glacial periods. The SHSK system of continental islands is valuable for understanding the impacts of Quaternary climate changes on the genetic diversity and evolutionary histories of boreal organisms. [ABSTRACT FROM AUTHOR]

The Southern Ocean regulates atmospheric CO2 and Earth's climate as a critical region for air‐sea gas exchange, delicately poised between being a CO2 source and sink. Here, we estimate how long a water mass has remained isolated from the atmosphere and utilize 14C/12C ratios (Δ14C) to trace the pathway and escape route of carbon sequestered in the deep ocean through the mixed layer to the atmosphere. The position of our core at the northern margin of the Southern Indian Ocean, tracks latitudinal shifts of the Southern Ocean frontal zones across the deglaciation. Our results suggest an expanded glacial Antarctic region trapped CO2, whereas deglacial expansion of the subantarctic permitted ventilation of the trapped CO2, contributing to a rapid atmospheric CO2 rise. We identify frontal positions as a key factor balancing CO2 outgassing versus sequestration in a region currently responsible for nearly half of global ocean CO2 uptake. Plain Language Summary: The Southern Ocean is a key region for the inhalation and exhalation of carbon dioxide, responsible for absorbing nearly half of the total amount of atmospheric c taken up by the modern global ocean. Today, regions of communication between the deep ocean and atmosphere are bounded by oceanographic fronts. During cold glacial periods, when sea ice cover expanded in the Southern Ocean, these regions were shifted northward. Our data shows that this northward movement pinched together the fronts in the Southern Indian Ocean, restricting glacial ocean‐atmosphere gas exchange, allowing CO2 to accumulate in the deep ocean. We find that at the end of the glaciation, the fronts returned southward and expanded, allowing transfer of the stored CO2 into intermediate and surface waters before escaping to the atmosphere. This trapping and releasing mechanism driven by frontal shifts is important for understanding how changes in Southern Ocean dynamics can affect the ability of the oceans to take up the additional atmospheric CO2 produced from human activities. Key Points: Indian Ocean Antarctic Intermediate Water was a pathway for ventilation of a deglacial carbon reservoirLatitudinal shifts in the Southern Ocean fronts contributed to glacial carbon storage and deglacial ventilationIntermediate waters of the Southern Indian Ocean were more than 2,000 years older in the deglaciation than the glacial and Holocene [ABSTRACT FROM AUTHOR]

Aim Location Taxon Methods Results Main Conclusions In northern environments, periods of isolation during Pleistocene glaciations and subsequent recolonization and secondary contact have had a significant influence on contemporary diversity of many species. The recent advent of high‐resolution genomic analyses allows unprecedented power to resolve genomic signatures of such events in northern species. Here, we provide the highest resolution genomic characterization of Atlantic salmon in North America to date to infer glacial refugia and the geographic scales of post‐glacial secondary contact.North America.Atlantic salmon, Salmo salar.Samples were collected for 5455 individuals from 148 populations, encompassing the majority of the Atlantic salmon's native range in North America, from Labrador to Maine. Individuals were genotyped using a 220K single nucleotide polymorphism array aligned to the Atlantic salmon (Salmo salar) genome. Spatial genetic structure (principal component analysis, k‐means clustering, admixture) was evaluated in conjunction with genomic comparisons of these identified lineages to infer the refugia during the last glacial maximum and regions of secondary contact following recolonization.Spatial genomic analyses identified three phylogeographic groups, consistent with the northward recolonization from two southern glacial refugia in North America (a western Maritime lineage and an eastern Newfoundland and Labrador lineage), with subsequent differentiation of the eastern lineage into two separate groups. Secondary contact among these North American groups was observed within the northern Gulf of St. Lawrence, and evidence of trans‐Atlantic secondary contact was detected within the eastern Newfoundland and Labrador lineage. Comparison of groups from insular Newfoundland with those from mainland Labrador suggests genomic regions displaying high differentiation were characterized by elevated European admixture, suggesting a possible role of European secondary contact in population divergence.These findings present the first evidence suggesting that genomic diversity in extant North American Atlantic salmon populations has resulted from allopatric isolation in two glacial refugia followed by both regional and trans‐Atlantic recolonization and secondary contact and demonstrate the power of genomic tools to resolve historical drivers of diversity in wild populations. [ABSTRACT FROM AUTHOR]

The pressure knapping technique develops circa 25,000 cal BP in Northeast Asia and excels at producing highly standardized microblades. Microblade pressure knapping spreads throughout most of Northeast Asia up to the Russian Arctic, and Alaska, in areas where the human presence was unknown. Swan Point CZ4b is the earliest uncontested evidence of human occupation of Alaska, at around 14,000 cal BP. It yields a pressure microblade component produced with the Yubetsu method, which is widespread in Northeast Asia during the Late Glacial period. Through the techno-functional analysis of 634 lithic pieces from this site, this study seeks to identify the techno-economical purposes for which the Yubetsu method was implemented. Data show that the microblade production system is related to an economy based on the planning of future needs, which is visible through blanks standardization, their overproduction, their functional versatility, and the segmentation of part of the chaîne opératoire. This expresses the efficiency and economic value of the microblade production system. The flexible use of pressure microblades identified at Swan Point CZ4b is also found in Japan, Korea, Kamchatka, and the North Baikal region, suggesting that their modes of use accompany the spread of early microblade pressure knapping over an immense territory across Beringia. [ABSTRACT FROM AUTHOR]

Uniformitarian theories of Martian history present many problems. A Biblical alternative is proposed that includes the Day-4 cratering hypothesis and Mars' crustal magnetism. Greatly reduced magnetism in the centers of the four largest impact craters suggests that most large Mars impacts occurred during the Genesis Flood. These impacts, and subsequent volcanism generated by them, produced a climate with sufficient liquid water for the Martian floods. A young age for Mars is supported by several geological observations. Rapid flooding can explain the valley networks and the outflow channels and provide a tighter volume estimate of around a 100 m Global Equivalent Layer (GEL). The flood water was absorbed into the subsurface and into hydrated minerals. That temporary atmosphere disappeared as water vapor precipitated out and the atmosphere cooled. Precipitation also absorbed CO2 and SO2 which helps account for their atmospheric disappearance. [ABSTRACT FROM AUTHOR]

The Intergovernmental Panel on Climate Change (IPCC) concluded that the latest decade was warmer than any multi-century period over the past 125,000 years. This statement rests on a comparison of modern instrumental measurements against the course of past temperatures reconstructed from natural proxy archives, such as lake and marine sediments, and peat bogs. Here, we evaluate this comparison with a focus on the hundreds of proxy records developed by paleoclimatologists across the globe to reconstruct climate variability over the Holocene (12,000 years) and preceded by the Last Glacial Period (125,000 years). Although the existing proxy data provide a unique opportunity to reconstruct low-frequency climate variability on centennial timescales, they lack temporal resolution and dating precision for contextualizing the most recent temperature extremes. While the IPCC's conclusion on the uniqueness of latest-decade warming is thus not supported by comparison with these smoothed paleotemperatures, it is still likely correct as ice core-derived forcing timeseries show that greenhouse gases were not elevated during any pre-instrumental period of the Holocene. [ABSTRACT FROM AUTHOR]

Investigation of rarely studied gravel layers found in the loess in Shandong Province, eastern China, reveals the fabric characteristics of two gravel layers (G1, G2) and the sedimentary characteristics of loess at the typical and well‐preserved Heiyu section (HY), where, to determine the paleoclimatic changes during Marine Isotope Stage 3a. Optically stimulated luminescence dates of the HY formation range from 0.26 ± 0.02 ka to 39.00 ± 2.00 ka. In addition, the ages of G1 and G2 were estimated using the Bayesian model to be 39.60–40.50 and 29.00–29.50 ka. G1 and G2 are mainly composed of fine and medium gravel, both of which were subangular to subrounded limestone, with gravel directions to NE and E. The average flow velocity, average depth, and flood peak flow of G1 are 1.10 m/s, 0.49 m, and 37.04 m3/s, respectively, calculated using the flow energy method, whereas those of G2 are 0.98 m/s, 0.38 m, and 18.38 m3/s, respectively. Analysis of climate proxy indices show that the sedimentary environment of the gravel and loess in HY might be a regional response to global change. [ABSTRACT FROM AUTHOR]

Evolutionary processes behind lineage divergence often involve multidimensional differentiation. However, in the context of recent divergences, the signals exhibited by each dimension may not converge. In such scenarios, incomplete lineage sorting, gene flow, and scarce phenotypic differentiation are pervasive. Here, we integrated genomic (RAD loci of 90 individuals), phenotypic (linear and geometric traits of 823 and 411 individuals, respectively), spatial, and climatic data to reconstruct the evolutionary history of a speciation continuum of liolaemid lizards (Liolaemus kingii group). Specifically, we (a) inferred the population structure of the group and contrasted it with the phenotypic variability; (b) assessed the role of postdivergence gene flow in shaping phylogeographic and phenotypic patterns; and (c) explored ecogeographic drivers of diversification across time and space. We inferred eight genomic clusters exhibiting leaky genetic borders coincident with geographic transitions. We also found evidence of postdivergence gene flow resulting in transgressive phenotypic evolution in one species. Predicted ancestral niches unveiled suitable areas in southern and eastern Patagonia during glacial and interglacial periods. Our study underscores integrating different data and model-based approaches to determine the underlying causes of diversification, a challenge faced in the study of recently diverged groups. We also highlight Liolaemus as a model system for phylogeographic and broader evolutionary studies. [ABSTRACT FROM AUTHOR]

Cherries (subg. Cerasus) belong to Prunus s.l. (Rosaceae) and are widely distributed in temperate and subtropical regions of the Northern Hemisphere. Given its ornamental and edible functions, it is a hugely preferred germplasm resource for human societies. However, the interspecific phylogenetic relationships, divergence times, and routes of this subgenus remain unclear. To reveal its enigmatic and intricate evolutionary history, we newly sequenced 12 subg. Cerasus species, reconstructed the plastome phylogeny with 24 previously published subg. Cerasus species. This study supports that subg. Cerasus split into five clades, among which P. mahaleb is the basal group of subg. Cerasus ; P. campanulata is genetically distantly related to P. cerasoides and is not recommended for treatment as a variety of the latter; P. subhirtella is involved in the speciation of P. yedoensis. Molecular dating and ancestral area reconstructions infer that subg. Cerasus originated in the Eastern Mediterranean–Central Asia before 11.57 Mya (95% HPD = 5.34–19.1 Mya) and subsequently spread into the Qinghai-Tibetan Plateau (QTP) and adjacent regions. The first dispersal event of modern subg. Cerasus was facilitated by 'out-of-QTP', colonizing North America across the Bering Land Bridge and re-dispersing into Europe from the Late Miocene to Pliocene and forming the initial distribution pattern of extant subg. Cerasus in the Pliocene; The end of the Quaternary glacial period witnessed a second dispersal event, and core subg. Cerasus population diversity flourished radially in its separate refugia during the Late Pleistocene. [ABSTRACT FROM AUTHOR]

This study presents the results of a 2D numerical basin and petroleum systems model of the Olga Basin in the NW Barents Sea offshore northern Norway, a frontier exploration area in which there are abundant seafloor oil and gas seepages. The effects of Pleistocene ice sheet advances on rock properties and subsurface fluid migration in this area, and on seafloor hydrocarbon seepage, are not well understood. The 2D numerical model takes account of recurrent ice advances and retreats, together with related erosional and temperature effects, and investigates the influence of these parameters on fluid migration. Model results show that Pleistocene glaciations reduced the temperature in the sedimentary succession in the Olga Basin by up to 20 °C, for example in the uppermost Cretaceous and Jurassic sediments which underlie the seafloor down to a depth of 0.5 to 1 km. The decrease in temperature was in general predominantly related to the intensity of glacial erosion, which was set in this study to a depth of 600 m based on previous studies. Hydrocarbon fluids expelled from potential thermogenic source rocks of Carboniferous to Triassic ages on the SW margin of the Olga Basin migrated to the seafloor through permeable carrier beds. However, fluid migration to the surface in the NE of the study area took place along fault conduits. In a closed fault model scenario, only 0.3 Mt of hydrocarbons are modelled to have migrated along the 0.5 km wide model section; in a second scenario with partially open faults, about 22 Mt of hydrocarbons, representing about 11% of the total hydrocarbons generated by potential thermogenic source rocks in the study area, were lost to the surface during the Pleistocene. The potential for microbial methane generation in the Olga Basin was limited both during the Pleistocene and at the present day due to the significant reduction in temperature during glacial episodes, and due to the intense glacial‐related erosion of the Mesozoic to Cenozoic stratigraphy. During glacial stages, the gas hydrate stability zone beneath the ice sheet is modelled to have extended to a depth of up to 900 m for a pure methane composition, and to a depth of up to 1100 m for a possible thermogenic‐sourced mixed gas composition of 90% methane, 7% propane and 3% ethane. Gas hydrates with this mixed composition are modelled to have been stable in the Olga Basin during the last three glacial advances and into the present. These modelling results provide an insight into the key factors controlling the migration and surface leakage of hydrocarbon fluids in the Olga Basin region, and into the effects of glaciations on rock properties in a glaciated basin. [ABSTRACT FROM AUTHOR]

The Sturtian "Snowball Earth" glaciation (ca. 717-661 Ma) is regarded as the most extreme interval of icehouse climate in Earth's history. The exact trigger and sustention mechanisms for this long-lived global glaciation remain obscure. The most widely debated causes are silicate weathering of the ca. 718 Ma Franklin large igneous province (LIP) and changes in the length and degassing of continental arcs. A new generation of two independent Neoproterozoic full-plate tectonic models now allows us to quantify the role of tectonics in initiating and sustaining the Sturtian glaciation. We find that continental arc length remains relatively constant from 850 Ma until the end of the glaciation in both models and is unlikely to play a role. The two plate motion models diverge in their predictions of the timing and progression of Rodinia break-up, ocean-basin age, ocean-basement depth, sea-level evolution, and mid-ocean ridge (MOR) carbon outflux. One model predicts MOR outflux and ocean basin volume-driven sea level lower than during the Late Cenozoic glaciation, while the other predicts outgassing and sea level exceeding those of the Late Cretaceous hothouse climate. The second model would preclude a major glaciation, while the first model implies that the trigger for the Sturtian glaciation could have been a combination of an extremely low MOR outflux (~9 Mt C/yr) and Franklin LIP weathering. Such minimal outflux could have maintained an icehouse state for 57 m.y. when silicate weathering was markedly reduced, with a gradual build-up of MOR CO2 in the atmosphere paired with terrestrial volcanism leading to its termination. [ABSTRACT FROM AUTHOR]

Glacial cycles lead to periodic population interbreeding and isolation in warm‐adapted species, which impact genetic structure and evolution. However, the effects of these processes on highly mobile and more cold‐tolerant species are not well understood. This study aims to shed light on the phylogeographic history of Aglais urticae, a butterfly species with considerable dispersal ability, and a wide Palearctic distribution reaching the Arctic. Through the analysis of genomic data, four main genetic lineages are identified: European, Sierra Nevada, Sicily/Calabria/Peloponnese, and Eastern. The results indicate that the Sardo‐Corsican endemic taxon ichnusa is a distinct species. The split between the relict lineages in southern Europe and the main European lineage is estimated to have happened 400–450 thousand years ago, with admixture observed during the Quaternary glacial cycles, and still ongoing, albeit to a much smaller extent. These results suggest that these lineages may be better treated as subspecific parapatric taxa. Ecological niche modelling supported the existence of both Mediterranean and extra‐Mediterranean refugia during the glacial periods, with the main one located on the Atlantic coast. Nevertheless, gene flow between populations was possible, indicating that both differentiation and admixture have acted continuously across glacial cycles in this cold‐tolerant butterfly, generally balancing each other but producing differentiated lineages in the southern peninsulas. We conclude that the population dynamics and the processes shaping the population genetic structure of cold‐adapted species during the Quaternary ice ages may be different than those classically accepted for warm‐adapted species. [ABSTRACT FROM AUTHOR]

Millennial-scale climate variations during the last glacial period, such as Dansgaard–Oeschger (DO) cycles and Heinrich events, have been extensively studied using ice core and marine proxy records. However, there is a limited understanding of the magnitude of these temperature fluctuations in continental regions, and questions remain about the seasonal signal of these climate events. This study presents a 60 000-year-long temperature reconstruction based on branched glycerol dialkyl glycerol tetraethers (brGDGTs) extracted from lake sediments from the Eifel Volcanic Field, Germany. brGDGTs are bacterial membrane-spanning lipids that are known to have a strong relationship with temperature, making them suitable for temperature reconstructions. We test several temperature calibration models on modern samples taken from soils and multiple maar lakes. We find a negative bias in brGDGT-based temperature estimates associated with water depth and anoxic conditions that can be corrected for by accounting for a brGDGT isomer that is only produced in anoxic conditions. The corrected temperature reconstruction correlates with proxy and climate model estimates of temperature spanning the same time period, validating the calibration approach we selected. However, millennial-scale variability is significantly dampened in the brGDGT record, and in contrast to other Northern Hemisphere climate records, during several Heinrich stadials, temperatures actually increase. We demonstrate that these apparent discrepancies can be explained by the unique seasonal response of the brGDGT paleothermometer to temperatures of months above freezing (TMAF). Our data support the view that warm-season temperatures in Europe varied minimally during the last glacial period and that abrupt millennial-scale events were defined by colder, longer winters. Our continuous high-resolution temperature reconstruction provides important information about the magnitude of seasonal climate variability during the last glacial period that can be used to test climate models and inform studies of paleoecological change. [ABSTRACT FROM AUTHOR]

Understanding the microscopic variability of impurities in glacier ice on a quantitative level has importance for assessing the preservation of paleoclimatic signals and enables the study of macroscopic deformational as well as dielectric ice properties. Two‐dimensional imaging via laser‐ablation‐inductively‐coupled‐plasma‐mass‐spectrometry (LA‐ICP‐MS) can provide key insight into the localization of impurities in the ice. So far, these findings are mostly qualitative and gaining quantitative insights remains challenging. Recent advances in LA‐ICP‐MS high‐resolution imaging now allow ice grains and grain boundaries to be resolved individually. These resolutions require new adequate quantification strategies and, consequently, accurate calibration with matrix‐matched standards. Here, we present three different quantification methods, which provide a high level of homogeneity at the scale of a few tens of microns and are dedicated to imaging applications of ice cores. One of the proposed methods has a second application, offering laboratory experiments to investigate the displacement of impurities by grain growth, with important future potential to study ice‐impurity interactions. Standards were analyzed to enable absolute quantification of impurities in selected ice core samples. Calibrated LA‐ICP‐MS maps indicate similar spatial distributions of impurities in all samples, while impurity levels vary distinctly: Higher concentrations were detected in glacial periods and Greenland, and lower levels in interglacial periods and samples from central Antarctica. These results are consistent with ranges from complementary meltwater analysis. Further comparison with cm‐scale melting techniques calls for a more sophisticated understanding of the ice chemistry across spatial scales, to which calibrated LA‐ICP‐MS maps now contribute quantitatively. Plain Language Summary: Compared to the large amount of information relating to paleoclimate signals reconstructed from cm‐scale impurity measurements on ice cores, knowledge about the spatial variability of impurities at the micro‐scale is extremely sparse—and becomes even more rare once quantitative datasets are concerned. However, there is an increasing demand for quantitative data for assessing the preservation of paleoclimatic signals and for the study of macroscopic deformational as well as dielectric ice properties in ice flow modeling and remote sensing. Two‐dimensional imaging via laser‐ablation‐inductively‐coupled‐plasma‐mass‐spectrometry (LA‐ICP‐MS) has shown great potential in this context, but so far, gaining reliable quantitative results for micro‐scale imaging has not been possible. Here, we present new quantification strategies that finally allow accurate calibration using ice standards. We carefully discuss the pros and cons of each method, apply the calibration to different samples from Greenland and Antarctica, and deliver the first calibrated LA‐ICP‐MS impurity maps at 40 μm resolution. Our results are consistent with bulk measurements performed on melted samples. The calibrated LA‐ICP‐MS maps will be essential for further comparison with bulk meltwater analysis, which may ultimately deliver an improved understanding of paleoclimate signals stored in deep ice. Key Points: This study presents new quantification strategies for two‐dimensional micro‐scale impurity imaging on ice cores with laser‐ablation‐inductively‐coupled‐plasma‐mass‐spectrometry (LA‐ICP‐MS)Calibrated LA‐ICP‐MS maps reveal similar spatial distributions of impurities in all ice core samples, while concentrations vary distinctlyWe developed a method to investigate the displacement of impurities by grain growth and to study ice‐impurity interactions in the laboratory [ABSTRACT FROM AUTHOR]

To describe the composition of the penultimate glacial Brazilian Atlantic forest, we analyzed pollen, charcoal and diatoms deposited in the section from 871 to 1400 cm of core CO14 drilled in the Colônia basin in southeastern Brazil. The landscape was characterized by a cool grassland with three conifer genera: Araucaria, Podocarpus and Ephedra. Total arboreal pollen frequency did not change during the transition from glacial to interglacial conditions. Changes in Podocarpus frequency and concentration showed out‐of‐phase responses with austral summer insolation at an orbital scale while, at a millennial scale, both northern and southern hemisphere ice volume controlled the interplay between positions of the Inter‐Tropical Convergence Zone and South Tropical Front (STF), which in turn defined the latitudinal distribution of rainfall. The disappearance of Podocarpus and the decrease of Araucaria observed between ~167 and 160 ka were related to a dry interval which was not observed elsewhere. During Termination II a progressive decrease in conifer pollen taxa was in phase with a southward shift in the STF and increase in Atlantic sea surface temperatures. Our results show that southern hemisphere conifer distribution is strongly linked to austral summer insolation and winter precipitation and will be threatened by the southward expansion of the summer rainfall boundary. [ABSTRACT FROM AUTHOR]

The California Current system (CCS) hosts one of the largest oxygen minimum zones (OMZs) in the world: the eastern North Pacific (ENP) OMZ, which is dissociated into subtropical and tropical regions (i.e. the ESTNP and ETNP). In the modern ENP OMZ, bioavailable nitrogen (N) is lost via denitrification and anaerobic ammonium oxidation (anammox). Even so, paleo-reconstructions of N loss have focused solely on denitrification. Fluctuations in bulk sedimentary δ15 N over glacial–interglacial cycles have been interpreted to reflect variations in denitrification rates in response to ETNP OMZ intensity changes. This δ15 N signal is thought to be transported northwards to the ESTNP OMZ. Here, we present the first CCS sedimentary record of ladderane lipids, biomarkers for anammox, located within the ESTNP OMZ (32° N, 118° W). Over the last two glacial terminations (∼ 160 kyr cal BP), ladderane concentrations were analysed in combination with the index of ladderanes with five cyclobutane moieties (NL 5), short-chain (SC) ladderane degradation products, and productivity proxies. This shows that (1) ladderanes were derived from anammox bacteria living within the ESTNP OMZ water column; (2) ladderanes were continuously present, with relatively high concentrations during both glacial and interglacial periods, showcasing that the ESTNP OMZ must have retained an anoxic core in which N loss occurred; and (3) anammox abundance appears to have been driven by both organic matter (OM) remineralization and advection changes, which regulated nutrient and oxygen levels. Our study shows that anammox was an important feature in the CCS, and it provides a more holistic picture of N-loss dynamics and the development of the ESTNP OMZ over glacial–interglacial cycles. Lastly, ladderanes and their SC products were also detected in 160–500 kyr cal BP sediments (15.7–37.5 m b.s.f., metres below sea floor; analysed at a low temporal resolution), highlighting their potential as anammox biomarkers in relatively deeper buried sediments for future studies. [ABSTRACT FROM AUTHOR]

The Mediterranean Sea is recognized as a hotspot of marine biodiversity. Analysing its past biodiversity can help in understanding species' response to climate change. We built a species-level dataset of bivalve occurrences across the Zanclean-Calabrian interval, a time characterized by significant changes in climate, and by bivalve extinctions. The dataset includes more than 400 species distributed from the eastern to the western Mediterranean Sea. We measured changes in richness and turnover through time, for the entire dataset, and for different palaeoenvironments and combinations of tiering and feeding categories to test if specific environmental conditions and different lifestyles were correlated to species extinction or survival through time. We also compared niche breadth, geographical range size, and species abundance of extinct and extant species, to test which of these parameters potentially affected extinction risk. Our results confirm a loss of biodiversity between 3 Ma and the Early Pleistocene, although this loss was less intense and more gradual than previously estimated. We also found significant differences in niche breadth and geographical range size between extinct and extant species. Suspension feeders lost a higher proportion of species and suffered a higher reduction of geographical range compared to infaunal deposit feeders. Species loss was more protracted and higher on the shoreface than on the shelf, which is probably related to the reduction of shallow-water vegetated environments and to the disaggregation of heterozoan carbonate ramp habitats with cooling and sea-level drop at the onset of the northern hemisphere glaciation. [ABSTRACT FROM AUTHOR]

The interpretation of high-resolution remote-sensed data (i.e., LiDAR-derived DTMs, aerial photos and satellite images), compared with ground-penetrating radar surveys, historical cartography, geomorphological surveys and stratigraphic data, allowed us to map a large system of dunes near the Grado-Marano Lagoon (NE Italy) and reconstruct its evolution. Remote sensing investigations allowed us to recognize, map and interpret the sandy reliefs as a field of continental aeolian landforms extending for over 15 km2 and consisting of parabolic dunes elongated in the WSW direction. Radar soundings, together with the description of stratigraphic sections and cores, documented the internal clinostratification of the dunes, supporting their aeolian origin. Radiocarbon dating documents that the dunes formed 22 ka ago, at the end of the Last Glacial Maximum, and probably evolved until the first part of the Late Glacial, when vegetation was scarce. The landforms were fed by the sands blown from a paleochannel of Isonzo River flowing eastward of the dune's field and blown by Bora. This is a very strong katabatic wind, still characterizing the area, but that was likely much stronger during last glaciation, when it was probably sustained by a stronger wind pattern in Central Europe. [ABSTRACT FROM AUTHOR]

Many north‐temperate tree species survived glacial periods in small, low‐density populations in refugia. These refugia are located in eastern and western North America, South Europe, East Asia, and western Asia. As a part of western Asia, Georgia harbors two main refugia: the Colchis in western Georgia and the eastern Great Caucasus, where many Cenozoic relict plants still exist. In this article, we report a new population of Pterocarya fraxinifolia (the Caucasian wingnut) which was discovered in the eastern Great Caucasus, near the village Lapankuri. The Lapankuri P. fraxinifolia stand is unique because the species grows not only in a narrow strip of riparian vegetation, but is also occurring in a broad band up to 100 m away from the river. Pterocarya fraxinifolia is dominant in the stand and is represented by large and old trees. Many other relict trees such as Diospyros lotus and Juglans regia are also present in the Lapankuri stand. Although some Cenozoic relict species are widely cultivated and naturalized in Central and Western Europe, natural stands of these plants provide the only evidence of their past growing conditions; therefore, conservation of this place is strongly advocated. [ABSTRACT FROM AUTHOR]

The southern three-banded armadillo, Tolypeutes matacus , is one of the most representative species of the South American Chaco region. The susceptibility of this species to climatic changes and its good number of paleontological records has led to the study of their range dynamics for untangling the effects of Quaternary oscillations. These studies yielded contradictory results, suggesting expansion processes under opposite conditions: some during glacial periods and others during interglacial periods. Here, we assess the population structure of T. matacus in Argentina based on mitochondrial genes, and estimate demographic and spatial dynamics that contribute to unveiling the evolutionary process that moulded its biogeography. We found no clear phylogeographical breaks, although there were differences in the composition and frequency of haplotypes between the northern and southern localities studied. Demographic inferences indicate that the species has undergone population and range expansion processes. The higher diversity found in the north and the spatial diffusion analysis allow us to infer a north–south direction of this expansive process. Our results yield essential evidence for disentangling the evolution of this Chacoan species linked with Quaternary climates and provide genetic information about its populations that should be taken into account for the conservation of this threatened mammal. [ABSTRACT FROM AUTHOR]

Only at Cape Surprise, central Transantarctic Mountains, is there exposed stratigraphic evidence for major offset along the range front, which marks a major boundary in Antarctica. Several faults parallel to the range front have been identified in the Devonian to Triassic Gondwana strata in the hinterland. Analysis of the stratigraphy based on field observations and the United States Geological Survey (USGS) aerial photographs, in conjunction with USGS topographic sheets and satellite-derived elevation measurements, suggests an array of faults with varying orientations and displacements. Fault offsets range up to an estimated 850 metres. No additional range-parallel faults have been identified and no clear pattern of faulting is evident in the hinterland of the frontal escarpment. Faulting may date from the time of slow uplift during the Cretaceous as well as the more rapid Cenozoic uplift of the range. Only a few faults in the hinterland can be allied with the fontal fault system. Cenozoic uplift and associated denudation was accompanied by glaciation of Antarctica, which is documented by Sirius Group strata. These deposits, which pre-date today's polar landscape, are older than mid Miocene, and in part may date from the earliest stages of warm-based glaciation in the early Oligocene. [ABSTRACT FROM AUTHOR]

Eriophyoid mites are among the most species‐rich superfamilies (Eriophyoidea) in the Acari, consisting of over 5000 named species. Although they exhibit a geographically uneven worldwide distribution, their regional spatiotemporal evolutionary patterns remain largely unknown. Here, we compiled a data set including 3058 occurrence records assigned into 1203 species in China. We found that eriophyoid mite species richness is higher in the southeast and lower in the northwest of China, coinciding with the 500‐mm annual precipitation isoline. Using fragments of two mitochondrial genes (COI, 12S rRNA) and two nuclear genes (18S rRNA, 28S rRNA) of 304 eriophyoid mite species, we constructed a regional dated phylogenetic tree in China. Our spatiotemporal analysis revealed that mountains in eastern and southern China had high eriophyoid mite species richness and phylogenetic clustering, possessing both ancient and young mite lineages. Species distribution modelling (SDM) results showed that the predicted suitable area of eriophyoid mites slightly expanded from the last inter‐glacial period to the last glacial maximum period. In comparison with the current SDM, a significantly larger distribution range was observed in future scenarios. These findings suggest that mountains in eastern and southern China acted as not only cradles—recent rapid speciation, but also museums—centre of gradual accumulation and preservation and provide insights into monitoring and conserving eriophyoid mites. [ABSTRACT FROM AUTHOR]

Given growing concerns about climate tipping points and their risks, it is important to investigate the capability of identifying robust precursor signals for the associated transitions. In general, the variance and short-lag autocorrelations of the fluctuations increase in a stochastically forced system approaching a critical or bifurcation-induced transition, making them theoretically suitable indicators to warn of such transitions. Paleoclimate records provide useful test beds if such a warning of a forthcoming transition could work in practice. The Dansgaard–Oeschger (DO) events are characterized by millennial-scale abrupt climate changes during the glacial period, manifesting most clearly as abrupt temperature shifts in the North Atlantic region. Some previous studies have found such statistical precursor signals for the DO warming transitions. On the other hand, statistical precursor signals for the abrupt DO cooling transitions have not been identified. Analyzing Greenland ice core records, we find robust and statistically significant precursor signals of DO cooling transitions in most of the interstadials longer than roughly 1500 years but not in the shorter interstadials. The origin of the statistical precursor signals is mainly related to so-called rebound events, humps in the temperature observed at the end of interstadial, some decades to centuries prior to the actual transition. We discuss several dynamical mechanisms that give rise to such rebound events and statistical precursor signals. [ABSTRACT FROM AUTHOR]

The late Asbian appears to mark the initial, well‐documented, onset of far‐field glacio‐eustatic changes in equatorial Mississippian strata. This work unravels the nature of cyclicity in upper Asbian shallow marine carbonates, using a combination of petrographic study, rock magnetic proxies and astrochronological testing on samples from the Trowbarrow section, NW England. Rock magnetic data express the content of two types of siliciclastic sources; a marine‐delivered magnetite‐dominated source, and an eolian‐delivered, hematite‐dominated source. The eolian‐sourced material generally peaked during regressive and low‐stand parts of the carbonate rhythms. Astrochronologic testing methods based around the average spectral misfit and TimeOpt methodology show the magnetite abundance proxies are principally carrying the astronomically forced signal. Two likely sedimentation rate models are derived from the five better magnetic proxies using evolutive methods. In addition, a set of three likely major hiatus levels are inferred in the sedimentation rate models, based on testing possible major hiatus scenarios with TimeOpt methods, using eccentricity modulation. From these, using the three best proxies, an average astrochronologic duration for the Trowbarrow section suggests a late Asbian duration of 1976 ± 86 kyr (1σ), and a basal late Asbian age of 334.48 ± 0.35 Ma (2σ). Coupled atmosphere‐ocean models for the late Paleozoic, suggest that lows in short eccentricity correspond to glacials, when inferred delivery of siliciclastic sediment to the carbonate ramp is generally at a maximum. The glacial and lower sea‐level intervals also coincide with maximum delivery of eolian siliciclastics, likely linked to increased aridity and less vegetation cover on adjacent and distal parts of Laurentia. Plain Language Summary: Around 332–333 million years ago changes in sea‐level driven by changes in polar ice volume were an important control on the sedimentation patterns through time in carbonates from low paleolatitudes. Understanding the pacing of these changes has implications for timescales and paleoceanographic processes. These cyclical changes in carbonate lithology are related to changes in magnetic properties within the late Asbian (late Visean) section at Trowbarrow in NW England. The magnetic changes principally express differences in the small content of silica‐based clastics, but also reflect changing Fe‐oxide mineralogy between times of hematite‐rich and magnetite‐rich clastic input. The changes are responding to differences in eolian delivery and marine dispersal of the clastics. Eolian delivery of clastics was at its peak near sea‐level lowstands, when nearby terrestrial systems were the most arid and supplying the most dust. Statistical assessments show that the magnetite abundance signal principally expresses changes in astronomical eccentricity. Primarily using the expected eccentricity pacing, two age models are constructed, which includes three levels of detectable hiatus in the section. Using these two age models and the three best magnetic proxies, the average late Asbian duration is 1976 ± 86 kyr, with the base of the late Asbian at 334.48 ± 0.35 Ma. Key Points: Rock magnetic properties show the included siliciclastics are from hematite‐rich eolian dust and marine‐dispersed sourcesThe magnetite mineral abundance proxies principally carry the primary eccentricity‐driven astronomical signalAn astrochronology for the late Asbian indicates its duration is 1976 ± 86 kyr [ABSTRACT FROM AUTHOR]

Estuaries are among the most productive ecosystems on Earth, yet they are at risk in high-latitude regions due to climate-driven effects on the connected terrestrial and marine realms. Northern Hemisphere warming exceeds the global average and accelerates the melting of glaciers. As a result, the magnitude of freshwater discharge into estuaries may increase during the peak in glacial meltwater, ultimately affecting the riverine flux of organic matter (OM) from the land to coastal environments and food webs within. We investigated the extent to which terrestrial OM subsidizes nearshore food webs in northern Gulf of Alaska watersheds and if differences in the relative proportion of terrestrial versus marine OM supporting these food webs are explained by watershed glacial cover and/or by seasonal glacial discharge regimes. A stable isotope mixing model was employed to determine the contribution of marine (phytoplankton, macroalgae) and terrestrial (vascular plant) sources to the diets of grazing/detritivore and filter/suspension-feeding coastal invertebrates at the outflows of watersheds of varying glacial influence and across three distinct discharge periods. Additionally, a distance-based redundancy analysis was conducted to investigate the effects of watershed-characteristic (e.g., slope, vegetation cover) sourcing and transport of terrestrial OM on consumer diets. The diets of both feeding groups were predominantly marine (> 90%) and varied little among estuarine study sites at watersheds of different glacial cover or glacial discharge periods. Our findings suggest that terrestrial OM is not readily used by nearshore food webs in this productive study system, presumably due to the high quantity and quality of available marine OM. [ABSTRACT FROM AUTHOR]

The Lac Fallère area in the upper Clusellaz Valley (tributary of the middle Aosta Valley) is shaped in micaschist and gneiss (Mont Fort Unit, Middle Penninic) and in calcschist and marble (Aouilletta Unit, Combin Zone). Lac Fallère exhibits an elongated shape and is hosted in a WSW–ENE-trending depression, according to the slope direction. This lake also shows a semi-submerged WSW–ENE rocky ridge that longitudinally divides the lake. This evidence, in addition to the extremely fractured rocks, indicates a wide, deep-seated gravitational slope deformation (DSGSD), even if this area is not yet included within the regional landslide inventory of the Aosta Valley Region. The Lac Fallère area also shows reliefs involved in glacial erosion (roches moutonnée), an extensive cover of subglacial sediments, and many moraines essentially referred to as Lateglacial. The DSGSD evolution in a glacial environment produced, as observed in other areas, effects on the facies of Quaternary sediments and the formation of a lot of wide moraines. Glacial slope sectors and lateral moraines displaced by minor scarps and counterscarps, and glaciers using trenches forming several arched moraines, suggest an interplay between glacial and gravitational processes, which share part of their evolution history. [ABSTRACT FROM AUTHOR]

Sharks are virtually absent from coastal Antarctica since the Late Eocene glaciations, but this group exhibited a notable austral diversity during the Cretaceous and Paleogene. Several species have already been described from the Aptian-Eocene successions of the Larsen Basin exposed in the James Ross Island area (northern Antarctic Peninsula) and the predominantly deep-water Hexanchiformes have a record that, although still rare, has been continually increased. Four species of this group are currently known from that basin: Notidanodon pectinatus, Xampylodon dentatus, Rolfodon thompsoni, and Rolfodon tatere. Such records are especially concentrated in the Gamma Member of the Snow Hill Island Formation (or Herbert Sound Member of Santa Marta Formation), on James Ross Island. Here we described four teeth assigned to X. dentatus and one identified as R. tatere from upper Campanian sections of James Ross Island, highlighting the nomenclatural changes that led to the definition of Xampylodon and Rolfodon. Some specimens of X. dentatus presented here are considerably more complete or represent teeth of different positions than most previous records. The material assigned to R. tatere represents the oldest record of this species in the world, extending its time range by more than 10 million years. [ABSTRACT FROM AUTHOR]

The drained shear strength of overconsolidated glaciolacustrine clays in the Seattle area can range from the overconsolidated peak to residual strength depending on its geologic history, depth, softening, prior shear displacements, size of excavation, and application, e.g., long-term cut slope versus short-term braced excavation. An inverse analysis of slope failures shows the mobilized shear strength for cut slopes in the overconsolidated and sparsely jointed Qvgl glaciolacustrine clay ranges from the fully softened strength to in between fully softened and residual strength depending on the level of jointing, prior shear displacements, assumed piezometric levels, and Atterberg limits used in the analysis. Conversely, an inverse analysis of a 2011 slope failure in the frequently jointed and random slickensided overconsolidated Qpgl glaciolacustrine clay shows the mobilized shear strength for this deposit near residual to in between residual and fully softened strengths because of repeated glaciation cycles, softening, and local shear displacements due to glacial bulldozing, solifluction, and high lateral stresses. [ABSTRACT FROM AUTHOR]

Information on the nature of processes occurring in modern glaciers can be obtained through the study of diamictons and landforms that are the product of past glaciations. Macrofabric and grain size analysis of late Quaternary glacial diamictons and moraines present in several valleys of the Serra da Cabreira Mountains in northwest Portugal revealed the presence of two types of diamictons deposited in different stages and were used to re-construct the glacial paleo process history of this mountainous region. Supraglacial melt-out tills and paraglacially reworked tills by debris flows are dominant in this range. Supraglacial melt-out tills, representative of periods of glacial stability followed by recession, present girdle to transitional fabrics and coarser to medium, poorly sorted sediments. Paraglacially reworked tills by debris flows, representative of postglacial mass wasting activity, present girdle fabrics and coarser, poorly sorted sediments. These diamictons and landforms are of particular importance in the reconstruction of the glacial dynamics and history of the Serra da Cabreira Mountains due to a scarcity of chronological data based on absolute dating methods. These Atlantic mountains are also the lowest glaciated range in the Iberian Peninsula, which makes them a compelling area to investigate mountain glacial dynamics in low-elevation Atlantic ranges. [ABSTRACT FROM AUTHOR]

Climate warming at the end of the last glacial period had profound effects on the distribution of cold-adapted species. As their range shifted towards northern latitudes, they were able to colonise previously glaciated areas, including remote Arctic islands. However, there is still uncertainty about the routes and timing of colonisation. At the end of the last ice age, reindeer/caribou (Rangifer tarandus) expanded to the Holarctic region and colonised the archipelagos of Svalbard and Franz Josef Land. Earlier studies have proposed two possible colonisation routes, either from the Eurasian mainland or from Canada via Greenland. Here, we used 174 ancient, historical and modern mitogenomes to reconstruct the phylogeny of reindeer across its whole range and to infer the colonisation route of the Arctic islands. Our data shows a close affinity among Svalbard, Franz Josef Land and Novaya Zemlya reindeer. We also found tentative evidence for positive selection in the mitochondrial gene ND4, which is possibly associated with increased heat production. Our results thus support a colonisation of the Eurasian Arctic archipelagos from the Eurasian mainland and provide some insights into the evolutionary history and adaptation of the species to its High Arctic habitat. [ABSTRACT FROM AUTHOR]

Dipterocarpoideae species form the emergent layer of Asian rainforests. They are the indicator species for Asian rainforest distribution, but they are severely threatened. Here, to understand their adaptation and population decline, we assemble high-quality genomes of seven Dipterocarpoideae species including two autotetraploid species. We estimate the divergence time between Dipterocarpoideae and Malvaceae and within Dipterocarpoideae to be 108.2 (97.8‒118.2) and 88.4 (77.7‒102.9) million years ago, and we identify a whole genome duplication event preceding dipterocarp lineage diversification. We find several genes that showed a signature of selection, likely associated with the adaptation to Asian rainforests. By resequencing of two endangered species, we detect an expansion of effective population size after the last glacial period and a recent sharp decline coinciding with the history of local human activities. Our findings contribute to understanding the diversification and adaptation of dipterocarps and highlight anthropogenic disturbances as a major factor in their endangered status. Dipterocarp trees are iconic but severely threatened species in Asian rainforests. This study assembles high-quality genomes of seven dipterocarp species to reveal the molecular basis of key adaptations and identifies a recent sharp population decline coinciding with local human activity. [ABSTRACT FROM AUTHOR]

The timing of the initial peopling of the Americas is unresolved. Because the archaeological record necessitates discussion of human entry from Beringia into southern North America during the last glaciation, addressing this problem routinely involves evaluating environmental parameters then targeting areas suitable for human settlement. Vertebrate remains indicate landscape quality and are a key dataset for assessing coastal migration theories and the viability of coastal routes. Here, radiocarbon dates on vertebrate specimens and archaeological sites are calibrated to document species occurrences and the ages of human settlements across the western expansion and decay of the Cordilleran Ice Sheet (CIS) during the Late Wisconsin Fraser Glaciation in four subregions of the north Pacific coast of North America. The results show archaeological sites occur after glacial maxima and are generally consistent with the age of other securely dated earliest sites in southern North America. They also highlight gaps in the vertebrate chronologies around CIS maxima in each of the subregions that point to species redistributions and extirpations and signal times of low potential for human settlement and subsistence in a key portion of the proposed coastal migration route. This study, therefore, defines new age constraints for human coastal migration theories in the peopling of the Americas debate. [ABSTRACT FROM AUTHOR]

To extract climatically relevant chemical signals from the deepest, oldest Antarctic ice, we must first understand the degree to which chemical ions diffuse within solid ice. Volcanic sulfate peaks are the ideal target for such an investigation because they are high amplitude, short duration (~3 years) events with a quasi-uniform structure. Here we present analysis of the EPICA Dome C sulfate record over the last 450 kyr. We identify volcanic peaks and isolate them from the non-sea salt sulfate background to reveal the effects of diffusion: amplitude damping and broadening of peaks in the time domain with increasing depth/age. Sulfate peak shape is also altered by the thinning of ice layers with depth that results from ice flow. Both processes must be simulated to derive effective diffusion rates. This is achieved by running a forward model to diffuse idealised sulfate peaks at different rates while also accounting for ice thinning. Our simulations suggest a median effective diffusion rate of sulfate ions of 2.4 ± 1.7 x 10-7 m2 yr-1 in the Holocene ice, slightly faster than suggested by previous work. The effective diffusion rate observed in deeper ice is significantly lower, and the Holocene ice shows the highest rate of the last 450 kyr. Beyond the Holocene, there is no systematic difference between the effective diffusion rates of glacial and interglacial periods despite variations in soluble ions concentrations, dust loading and ice grain radii. Effective diffusion rates for 40 to 200 ka are relatively constant, on the order of 1 x 10-8 m2 yr-1. Our results suggests that the diffusion of sulfate ions within volcanic peaks is relatively fast initially, perhaps through the inter-connected vein network, but slows significantly after 40 kyr. In the absence of clear evidence for a controlling environmental factor on sulfate diffusivity with depth/age, we hypothesize that the rapid decrease in diffusion rate from the time of deposition to ice of 50 ka age may be due to a switch in the mechanism of diffusion resulting from the changing location of sulfate ions within the ice microstructure. [ABSTRACT FROM AUTHOR]

The long-term burial of organic carbon in marginal seas plays a critical role in Earth's carbon cycle and climate change. However, the mechanism of organic carbon (OC) burial in the Okinawa Trough (OT) during glacial-interglacial timescales remains unclear. In this study, we analyzed the foraminiferal carbon isotopes, total organic carbon (TOC), and d13C-TOC over the past 200 ka in core Z1 collected in the central OT. We aimed to reveal the history of OC burial in the middle Okinawa Trough during the past 200 ka, and we combined our findings with relevant paleoenvironmental indices to reveal underlying mechanisms. We found reduced surface primary productivity during MIS 6, which may indicate changes in the pathways of the Kuroshio Current (KC). Furthermore, we observed decoupling between high TOC flux and low OC burial during glacial periods. We proposed that the dilution effect caused by the high sedimentation rate and poor OC preservation during the glacial period resulted in the low TOC content. Ventilation of the North Pacific Intermediate Water (NPIW) regulated the redox conditions of the intermediate water in the Okinawa Trough. Additionally, the intensified Kuroshio Current during interglacial phases led to water column stratification, creating reducing conditions in the bottom water and facilitating improved OC preservation. Subsequently, the enhanced water column oxygenation resulting from the oxygen carried by the intensified glacial NPIW weakened the burial of OC. This study sheds new light on our understanding of the carbon cycle in marginal seas on a glacial-interglacial timescale. [ABSTRACT FROM AUTHOR]

The variability of Arctic sea-ice during abrupt stadial-interstadial shifts in the last glacial period remain poorly understood. Here, we investigated the millennial-scale relationship, with a focus on Heinrich Stadials (HS), between sea-ice cover and bottom water temperature (BWT) during Marine Isotope Stages (MIS) 3 and 2 (64–13 ka) in the Fram Strait using new molecular sea ice biomarker data and published benthic foraminiferal BWT records. Widespread spring sea-ice cover (SpSIC) dominated the studied interval, especially in mid-late MIS 3 (45–29 ka). Yet, warm interstadials were characterized by relatively more open-ocean conditions compared to cold stadials. At the transition between a HS and the subsequent interstadial, sea ice was tightly linked to BWT with rapid reductions in SpSIC coinciding with lower BWT at the end of HS. The relative timing of the events, especially during HS 1, points to ocean warming as the key controlling factor for sea ice reduction at millennial timescales. [ABSTRACT FROM AUTHOR]

Biological systems occurring in ecologically heterogeneous and spatially discontinuous habitats provide an ideal opportunity to investigate the relative roles of neutral and selective factors in driving lineage diversification. The grey mangroves (Avicennia marina) of Arabia occur at the northern edge of the species' range and are subject to variable, often extreme, environmental conditions, as well as historic large fluctuations in habitat availability and connectivity resulting from Quaternary glacial cycles. Here, we analyse fully sequenced genomes sampled from 19 locations across the Red Sea, the Arabian Sea and the Persian/Arabian Gulf (PAG) to reconstruct the evolutionary history of the species in the region and to identify adaptive mechanisms of lineage diversification. Population structure and phylogenetic analyses revealed marked genetic structure correlating with geographic distance and highly supported clades among and within the seas surrounding the Arabian Peninsula. Demographic modelling showed times of divergence consistent with recent periods of geographic isolation and low marine connectivity during glaciations, suggesting the presence of (cryptic) glacial refugia in the Red Sea and the PAG. Significant migration was detected within the Red Sea and the PAG, and across the Strait of Hormuz to the Arabian Sea, suggesting gene flow upon secondary contact among populations. Genetic‐environment association analyses revealed high levels of adaptive divergence and detected signs of multi‐loci local adaptation driven by temperature extremes and hypersalinity. These results support a process of rapid diversification resulting from the combined effects of historical factors and ecological selection and reveal mangrove peripheral environments as relevant drivers of lineage diversity. [ABSTRACT FROM AUTHOR]

The reduction in the area and volume of glaciation in all mountain regions of the Earth has strongly accelerated for the last decades. In this work, we analysed the trends of the main climatic parameters which caused the glacier recession in the Kamchatka Peninsula. It was shown that the glaciers of the northern part of the Sredinny Range decreased by 125 km2 (35.6%) from 1950 to 2016–2017. The average rate of their reduction in the period from 2002 to 2016–2017 (1.45%/year) increased approximately 4.3 times compared to the period 1950–2002 (0.34%/year). The greatest reduction is observed in small glaciers with an area of less than 0.1 km2 and in glaciers with southeastern and southern expositions. On the Kronotsky Peninsula, the glacier area reduction for 1957–2019 was equal to 32.1 km2 (35.6%), and the rates were almost the same in the periods of 1957–2000 (0.61%/year) and 2000–2019 (0.67%/year). According to the data of weather stations and ERA5 reanalysis, it was shown that, in the ablation (summer) period the warming rate was minimal (0.3°C/10 years) and in the accumulation period a significant decrease in precipitation (5%–10%/10 years) was revealed in some areas. At the same time, a significant increase in the radiation balance was revealed in the warm season along with a tendency in downward shortwave radiation increase for the last two decades due to a decrease in cloud amount. These trends are in good agreement with the growth of the geopotential height over the North Pacific during the warm season in the 21st century, and with the growth of velocity divergence in the middle troposphere and the intensification of downward air movements. All this confirms an increase in anticyclone frequency in the warm season, which could be the cause of a radiation balance increase and, consequently, an increase in glacier ablation. [ABSTRACT FROM AUTHOR]

A tipping point is defined by the IPCC as a critical threshold beyond which a system reorganizes, often abruptly and/or irreversibly. Tipping points can be crossed solely by internal variation in the system or by approaching a bifurcation point where the current state loses stability and forces the system to move to another stable state. It is currently debated whether or not Dansgaard-Oeschger (DO) events, abrupt warmings occurring during the last glacial period, are noise-induced or caused by the system reaching a bifurcation point. It can be shown that before a bifurcation point is reached there are observable changes in the statistical properties of the state variable. These are known as early warning signals and include increased fluctuation and correlation time. To express this behaviour we propose a new model based on the well-known first order autoregressive process (AR), with modifications to the correlation parameter such that it depends linearly on time. In order to estimate the time evolution of the correlation parameter we adopt a hierarchical Bayesian modeling framework, from which Bayesian analysis can be performed using the methodology of integrated nested Laplace approximations. We then apply the model to segments of the oxygen isotope ratios from the Northern Greenland Ice Core Project record corresponding to 17 DO events. Early warning signals were detected and found statistically significant for a number of DO events, suggesting that such events could indeed be caused by approaching a bifurcation point. The methodology developed to perform the given early warning analyses can be applied more generally, and is publicly available as the R-package INLA.ews. [ABSTRACT FROM AUTHOR]