Predicting natural arsenic enrichment in peat-bearing, alluvial and coastal depositional systems: A generalized model based on sequence stratigraphy

Hazardously high concentrations of arsenic exceeding the threshold limits for soils and drinking waters have been widely reported from Quaternary sedimentary successions and shallow aquifers of alluvial and coastal lowlands worldwide, raising public health concerns due to potential human exposure to arsenic. A combined sedimentological and geochemical analysis of subsurface deposits, 2.5-50 m deep, from the SE Po Plain (Italy) documents a systematic tendency for naturally-occurring arsenic to accumulate in peat-rich layers, with concentrations invariably greater than maximum permissible levels. A total of 366 bulk sediment samples from 40 cores that penetrated peat-bearing deposits were analysed by X-ray fluorescence. Arsenic concentrations associated with 7 peat-free lithofacies associations (fluvial-channel, levee/crevasse, floodplain, swamp, lagoon/bay, beach-barrier, and offshore/prodelta) exhibit background values invariably below threshold levels (<20 mg/kg). In contrast, total arsenic contents from peaty clay and peat showed 2-6 times larger As accumulation. A total of 204 near-surface (0-2.5 m) samples from modern alluvial and coastal depositional environments exhibit the same trends as their deeper counterparts, total arsenic peaking at peat horizons above the threshold values for contaminated soils. The arsenic-bearing, peat-rich Quaternary successions of the Po Plain accumulated under persisting reducing conditions in wetlands of backstepping estuarine and prograding deltaic depositional environments during the Early-Middle Holocene sea-level rise and subsequent stillstand. Contamination of the Holocene and underlying Pleistocene aquifer systems likely occurred through the release of As by microbially-mediated reductive dissolution. Using high-resolution sequence-stratigraphic concepts, we document that the Late Pleistocene-Holocene lithofacies architecture dictates the subsurface distribution of As. The "wetland trajectory", i.e. the path taken by the landward/seaward shift of peat-rich depositional environments during the Holocene, may help predict spatial patterns of natural As distribution, delineating the highest As-hazard zones and providing a realistic view of aquifer contamination even in unknown areas.

A 1 Ma sedimentary ancient DNA (sedaDNA) record of catchment vegetation changes and the developmental history of tropical Lake Towuti (Sulawesi, Indonesia)

Studying past ecosystems from ancient environmental DNA preserved in lake sediments (sedaDNA) is a rapidly expanding field. This research has mainly involved Holocene sediments from lakes in cool climates, with little known about the suitability of sedaDNA to reconstruct substantially older ecosystems in the warm tropics. Here, we report the successful recovery of chloroplast trnL (UAA) sequences (trnL-P6 loop) from the sedimentary record of Lake Towuti (Sulawesi, Indonesia) to elucidate changes in regional tropical vegetation assemblages during the lake's Late Quaternary paleodepositional history. After the stringent removal of contaminants and sequence artifacts, taxonomic assignment of the remaining genuine trnL-P6 reads showed that native nitrogen-fixing legumes, C3 grasses, and shallow wetland vegetation (Alocasia) were most strongly associated with >1-million-year-old (>1 Ma) peats and silts (114-98.8 m composite depth; mcd), which were deposited in a landscape of active river channels, shallow lakes, and peat-swamps. A statistically significant shift toward partly submerged shoreline vegetation that was likely rooted in anoxic muddy soils (i.e., peatland forest trees and wetland C3 grasses (Oryzaceae) and nutrient-demanding aquatic herbs (presumably Oenanthe javanica)) occurred at 76 mcd (~0.8 Ma), ~0.2 Ma after the transition into a permanent lake. This wetland vegetation was most strongly associated with diatom ooze (46-37 mcd), thought to be deposited during maximum nutrient availability and primary productivity. Herbs (Brassicaceae), trees/shrubs (Fabaceae and Theaceae), and C3 grasses correlated with inorganic parameters, indicating increased drainage of ultramafic sediments and laterite soils from the lakes' catchment, particularly at times of inferred drying. Downcore variability in trnL-P6 from tropical forest trees (Toona), shady ground cover herbs (Zingiberaceae), and tree orchids (Luisia) most strongly correlated with sediments of a predominantly felsic signature considered to be originating from the catchment of the Loeha River draining into Lake Towuti during wetter climate conditions. However, the co-correlation with dry climate-adapted trees (i.e., Castanopsis or Lithocarpus) plus C4 grasses suggests that increased precipitation seasonality also contributed to the increased drainage of felsic Loeha River sediments. This multiproxy approach shows that despite elevated in situ temperatures, tropical lake sediments potentially comprise long-term archives of ancient environmental DNA for reconstructing ecosystems, which warrants further exploration.

Nomenclatural history of Megalonyx Jefferson, 1799 (Mammalia, Xenarthra, Pilosa, Megalonychidae)

Both authorship and spelling of the extinct giant sloth genus Megalonyx and its type species, M.jeffersonii (Mammalia, Xenarthra, Pilosa, Megalonychidae), have been inconsistent. The genus-group name has been cited with two different authorships and three dates, and it has been spelled with two different suffixes. The species-group name has been cited with four different authors and dates, and it has been spelled with two different endings. Megalonyx Jefferson, 1799 is the first valid use of the genus-group name; the correct original spelling has the -onyx suffix. The type species of Megalonyx is Megatheriumjeffersonii Desmarest, 1822; the correct original spelling has an -ii ending. A vernacular word, megalonyx, refers to species classified in the genus Megalonyx Jefferson, 1799.

Evolutionary history of a cold-adapted limnephilid caddisfly: Effects of climate change and topography on genetic structure

The distribution of organisms is influenced by complex factors such as the phylogenetic evolutionary histories of species, the physiological and ecological characteristics of organisms, climate, and geographical and geohistorical features. In this study, we focused on a caddisfly, Asynarchus sachalinensis (Trichoptera: Limnephilidae), which has adapted to cold habitats. From phylogeographic analyses based on the mitochondrial DNA (mtDNA) cytochrome c oxidase subunit I (COI) and 16S rRNA regions and the nuclear DNA (nDNA) 18S rRNA, 28S rRNA, carbamoyl-phosphate synthetase (CAD), elongation factor-1 alpha (EF1-α), and RNA polymerase II (POLII) regions, two distinct genetic clades were detected. Clade I was shown to be widely distributed from Sakhalin to Honshu, whereas Clade II was only distributed within Honshu. The distributions of these clades overlapped in Honshu. The habitats were located at relatively lower altitudes for Clade I and higher altitudes for Clade II. The divergence time of these clades was estimated to be during the Pleistocene, indicating that repeated climatic changes facilitated distributional shifts. Haplotype network and demographic analyses based on the mtDNA COI region showed contrasting genetic structures in the two clades. It was indicated that the population sizes of Clade I had expanded rapidly in a recent period, whereas Clade II had maintained stable population sizes. The habitats of Clade II were typically isolated and scattered at high altitudes, resulting in restricted migration and dispersal because of their discontinuous "Sky Island" habitats. The habitats of Clade I were located at relatively low altitudes, and it was assumed that the populations were continuous, which resulted in a higher frequency of migration and dispersal between populations. Thus, differences in the spatial scale of the adapted habitats of each clade may have resulted in different patterns of population connectivity and fragmentation associated with repeated climatic changes during the Pleistocene. Our study provided new insight into the distributional patterns of cold-adapted aquatic insects in the Japanese Archipelago. Furthermore, the distributional shifts predicted by ecological niche modeling under future climatic change conditions were different for each clade. Therefore, different principles are required in the assessment of each clade to predict temporal changes in their distributions.

The Holocene record of the slow loris (Nycticebus sp.) in Java (Indonesia)

OBJECTIVES

(Sub)fossil lorises are rare in Southeast Asia. Their taxonomic relationship with extant populations, and the extent to which their distribution and morphology are influenced by changing environmental conditions, remains poorly understood. This study provides a synthesis of Nycticebus occurrences in Holocene Java. A morphometric analysis of a sample of craniodental remains aims to improve our understanding of their taxonomic status. Morphometrics were also used to explore potential size changes during the Holocene.

MATERIALS AND METHODS

Based on the literature and a review of museum catalogs, a synthesis was compiled of (sub)fossil slow loris occurrences in Java. Morphometric data on the mandible and maxilla of 10 (sub)fossil lorises were compared with a dataset of extant specimens to assess variation in size and shape.

RESULTS

Five Holocene Nycticebus occurrences were identified in eastern Java. All specimens fall in the range of N. javanicus and N. coucang. The specimens from Hoekgrot, Gua Jimbe, and Sampung suggest an affinity to N. javanicus. The remains from Gua Jimbe and Hoekgrot gave values close to the largest N. javanicus specimens, but the (presumably older) Song Terus specimen was of average size.

DISCUSSION AND CONCLUSIONS

The distribution of Nycticebus suggests that it originally occurred throughout the island. The remains are probably best identified as N. javanicus or N. coucang, but the Neolithic finds from Hoekgrot and Gua Jimbe are presumably N. javanicus. Size variation in Nycticebus was clinal, but although some large specimens were present, no evidence was found for size diminution during the Holocene.

Biogeography and environmental preferences of Butia yatay (Mart.) Becc

During the Quaternary, Chaco Phytogeographic Domain (Chaco) flora in subtropical South America experienced temperature and humidity fluctuations, primarily driven by wind dynamics, leading to significant shifts in species distribution. The palm Butia yatay is endemic to the Chaco and thrives in areas characterized by a warm-rainy climate and mostly restricted to sandy soils. To investigate the current geographic distribution of suitable habitat for B. yatay while assessing the significance of soil variables, we employed two distinct algorithms in species distribution modeling (SDM). We also determined whether the distribution of B. yatay has changed since the Pleistocene and whether these changes align with previously proposed Pleistocene refugia. In the present SDMs, we considered two separate sets of predictors, one set with bioclimatic variables only and the other set with bioclimatic topographic and soil variables. Additionally, we reconstructed the historical geographic distribution of suitable habitats using bioclimatic data. Our results suggested that the primary determinants of B. yatay's current distribution include precipitation and temperature of the driest month and soil cation exchange capacity. Incorporating soil variables affected the estimated size and range of suitable areas. Projections into the past indicated similar suitable habitat distributions during interglacial periods compared with the present. During the Last Glacial Maximum, climatically suitable habitat may have shifted northward, partially overlapping with previously suggested Pleistocene refugia located between the Paraná and Uruguay Rivers. These findings indicate the main factors driving the distribution and ecology of B. yatay and enhance understanding of subtropical flora shifts during the Quaternary. The approach also may prove valuable for other studies within the Chaco.

The Deep Past of the White Shark, Carcharodon carcharias, in the Mediterranean Sea: A Synthesis of Its Palaeobiology and Palaeoecology

The white shark, Carcharodon carcharias, is the main top predator of the present-day Mediterranean Sea. The deep past of C. carcharias in the Mediterranean is witnessed by a rather conspicuous, mostly Pliocene fossil record. Here, we provide a synthesis of the palaeobiology and palaeoecology of the Mediterranean white sharks. Phenetically modern white shark teeth first appeared around the Miocene-Pliocene transition in the Pacific, and soon after in the Mediterranean. Molecular phylogenetic analyses support an origin of the Mediterranean white shark population from the dispersal of Australian/Pacific palaeopopulations, which may have occurred through the Central American Seaway. Tooth dimensions suggest that the Mediterranean white sharks could have grown up to about 7 m total length during the Pliocene. A richer-than-today marine mammal fauna was likely pivotal in supporting the Mediterranean white sharks through the Pliocene and most of the Quaternary. White sharks have seemingly become more common as other macropredators declined and disappeared, notwithstanding the concurrent demise of many potential prey items in the context of the latest Pliocene and Quaternary climatic and environmental perturbations of the Mediterranean region. The overall generalist trophic habits of C. carcharias were likely crucial for securing ecological success in the highly variable Mediterranean scenario by allowing the transition to a mostly piscivorous diet as the regional marine mammal fauna shrank.

Distribution patterns of Quercus ilex from the last interglacial period to the future by ecological niche modeling

The plants' geographic distribution is affected by natural or human-induced climate change. Numerous studies at both the global and regional levels currently focus on the potential changes in plant distribution areas. Ecological niche modeling can help predict the likely distribution of species according to environmental variables under different climate scenarios. In this study, we predicted the potential geographic distributions of Quercus ilex L. (holm oak), a keystone species of the Mediterranean ecosystem, for the Last Interglacial period (LIG: ~130 Ka), the Last Glacial Maximum (LGM: ~22 Ka), mid-Holocene (MH: ~6 Ka), and future climate scenarios (Representative Concentration Pathway (RCP) 4.5 and 8.5 scenarios) for 2050-2070 obtained from CCSM4 and MIROC-ESM global climate scenarios respectively. The models were produced with algorithms from the R-package "biomod2" and assessed by AUC of the receiver operating characteristic plot and true skill statistics. Aside from BIOCLIM (SRE), all model algorithms performed similarly and produced projections that are supported by good evaluation scores, although random forest (RF) slightly outperformed all the others. Additionally, distribution maps generated for the past period were validated through a comparison with pollen data acquired from the Neotoma Pollen Database. The results revealed that southern areas of the Mediterranean Basin, particularly coastal regions, served as long-term refugia for Q. ilex, which was supported by fossil pollen data. Furthermore, the models suggest long-term refugia role for Anatolia and we argue that Anatolia may have served as a founding population for the species. Future climate scenarios indicated that Q. ilex distribution varied by region, with some areas experiencing range contractions and others range expands. This study provides significant insights into the vulnerability of the Q. ilex to future climate change in the Mediterranean ecosystem and highlights the crucial role of Anatolia in the species' historical distribution.

Pampean megamammals in Europe: the fossil collections from Santiago Roth

Santiago Roth was a Swiss fossil finder, naturalist, and paleontologist that emigrated to Argentina in 1866. His work largely influenced the discipline in the country at the end of the twentieth century, particularly the stratigraphy of the Pampean region. Some of his collections of Pampean fossils were sold to museums and private collectors in Europe and were accompanied by elaborated catalogues. Fossils in the Roth's catalogues N° 2 and 3 are housed today in the Natural History Museum of Denmark, fossils from catalogues N° 4 to 6, were sold to Swiss museums, with Catalogue N° 5 currently housed at the Department of Paleontology, Universität Zürich. Here, we provide a general framework on the stratigraphy from the Roth's Pampean fossil sites, summarize the history of the Pampean fossils in Europe originally collected by Roth, and provide historical and curatorial details of the Roth's collection at the Department of Paleontology, Universität Zürich.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13358-023-00283-5.

Quaternary 2D Monolayer Cu2Cl2Se2Hg2: Anisotropic Carrier Mobility and Tunable Bandgap for Transistor and Photocatalytic Applications

Despite the advantages of quaternary 2D materials, fewer studies have been done on them than binary 2D materials. Calculations of quaternary 2D monolayer Cu2Cl2Se2Hg2 based on density functional theory and Green's function surface analysis provide insights into its structural, dynamic, and thermal stability. This material has a direct band gap of 0.91/2.0 eV (PBE/HSE06) and demonstrates anisotropic carrier mobility. The electron mobility in the a direction is 1.2×103 cm2/V/s, which is significantly higher than the hole mobility of 0.48×103 cm2/V/s. In the b direction, the electron mobility is 1.01×103 cm2/V/s and is 8.9 times larger than the hole mobility of 0.11×103 cm2/V/s. The light absorption coefficients of Cu2Cl2Se2Hg2 are 1.0 ×105 /cm and 2.5 ×105 /cm in the visible and ultraviolet ranges, respectively. Uniaxial strain leads to an anisotropic alteration in the band gap and band edge position. By manipulating the strain direction and level in Cu2Cl2Se2Hg2, it is possible to increase the current ON/OFF ratio for field-effect transistors and to facilitate photocatalytic water splitting through a redox reaction. The research reveals that Cu2Cl2Se2Hg2, a 2D monolayer in the quaternary form, has promising capabilities as an alternative for creating crystal-oriented field-effect transistors and photocatalytic water splitting systems.

Caviomorph rodents from the Pampean region (Argentina) in the historical Santiago Roth Collection in Switzerland

Here I reviewed the Pleistocene caviomorphs collected by Santiago Roth (collection from Catalog No. 5) and housed at the paleontological collection of the Paläontologisches Institut und Museum, Universität Zürich, Zurich (Switzerland). The fossils were found in Pleistocene strata from Buenos Aires and Santa Fé provinces (Argentina) during the late nineteenth century. The material includes craniomandibular remains assigned to Lagostomus maximus (Chinchilloidea: Chinchillidae), craniomandibular and postcranial (thoracic and sacral vertebra, left scapula, left femur, and right tibia) bones identified as Dolichotis sp. (Cavioidea: Caviidae), and a fragmented hemimandible and isolated tooth of Myocastor sp. (Octodontoidea: Echimyidae). Other rodent specimens from this collection (Ctenomys sp. and Cavia sp.) are possibly sub-recent materials.

Study on the relationship between hydrodynamic conditions and arsenic content in Quaternary sediments

Groundwater is susceptible to arsenic contamination by sediment with high arsenic content, which is the primary culprit of regional arsenic pollution and poisoning. To explore the influence of the change in hydrodynamic conditions caused by changes in the sedimentary environment over time on arsenic content in sediments during the Quaternary, the hydrodynamic characteristics and arsenic content enrichment of borehole sediments were studied in typical high-arsenic groundwater areas of the Jianghan-Dongting Basin, China. The regional hydrodynamic conditions represented by each borehole location were analyzed, the correlation between the variation in groundwater dynamics characteristics and arsenic content in different hydrodynamic periods was analyzed, and the relationship between arsenic content and grain size distribution was quantitatively investigated using grain size parameter calculation, elemental analysis, and statistical estimates of arsenic content in borehole sediments. We observed that the relationship between arsenic content and hydrodynamic conditions differed between sedimentary periods. Furthermore, arsenic content in the sediments from the borehole at Xinfei Village was significantly and positively correlated with a grain size of 127.0-240.0 μm. For the borehole at Wuai Village, arsenic content was significantly and positively correlated with a grain size of 1.38-9.82 μm size (at 0.05 level of significance). However, arsenic content was inversely correlated with grain sizes of 110.99-716.87 and 133.75-282.07 μm at p values of 0.05 and 0.01, respectively. For the borehole at Fuxing Water Works, arsenic content was significantly and positively correlated with a grain size of 409.6-655.0 μm size (at 0.05 level of significance). Arsenic tended to be enriched in transitional and turbidity facies sediments with normal corresponding hydrodynamic strength but poor sorting. Furthermore, continuous and stable sedimentary sequences were conducive to arsenic enrichment. Fine-grain sediments provided abundant potential adsorption sites for high-arsenic sediments, but finer particle size was not correlated with higher arsenic levels.

Centers of Excellence: If We Build It, Will They Come?

Pediatric surgeons have been pursuing high quality, affordable care or value-based care for over 50 years. One approach to streamlining the clinical care for a complex problem was the development of a center of excellence (COE). The concept of COE focuses on a shared vision of providing high quality care through a multidisciplinary approach. The goal is to improve diagnostic accuracy as well as therapeutic outcomes using focused expertise within a group. COEs are often resource intensive before becoming fiscally viable and therefore require initial support from hospital leadership. This review discusses the key steps to consider before building a COE, strategies to help build one, and how to keep one successful as defined by quality, accessibility, equity, training, and maintaining teams within the group.

Defaunation and species introductions alter long-term functional trait diversity in insular reptiles

Biodiversity loss poses a major threat to ecosystem function, which has already been severely impacted by global late-Quaternary defaunation. The loss of mammalian megafauna from many insular systems has rendered reptiles into key modulators of many ecosystem services, such as seed dispersal and pollination. How late-Quaternary extinction events impacted reptile functional diversity remains unclear but can provide critical guidance on traits that render reptiles vulnerable to extinction, as well as anthropogenic, environmental, and evolutionary histories that may promote stability and resilience. This study reconstructs the trajectory of functional diversity change in the Caribbean reptile fauna, a speciose biota distributed over a diverse set of islands with heterogeneous histories of human habitation and exploitation. Human-induced Quaternary extinctions have completely removed key functional entities (FEs)-groupings of species with similar traits that are expected to provide similar ecosystem services-from the region, but functional redundancy on large islands served as a buffer to major functional diversity loss. Small islands, on the other hand, lose up to 67% of their native FEs with only a few exceptions, underscoring the importance of a place's anthropogenic history in shaping present-day biodiversity. While functional redundancy has shielded ecosystems from significant functional diversity loss in the past, it is being eroded and not replenished by species introductions, leaving many native FEs and the communities that they support vulnerable to extinction and functional collapse. This research provides critical data on long-term functional diversity loss for a taxonomic group whose contributions to ecosystem function are understudied and undervalued.

Beringia and the peopling of the Western Hemisphere

Did Beringian environments represent an ecological barrier to humans until less than 15 000 years ago or was access to the Americas controlled by the spatial-temporal distribution of North American ice sheets? Beringian environments varied with respect to climate and biota, especially in the two major areas of exposed continental shelf. The East Siberian Arctic Shelf ('Great Arctic Plain' (GAP)) supported a dry steppe-tundra biome inhabited by a diverse large-mammal community, while the southern Bering-Chukchi Platform ('Bering Land Bridge' (BLB)) supported mesic tundra and probably a lower large-mammal biomass. A human population with west Eurasian roots occupied the GAP before the Last Glacial Maximum (LGM) and may have accessed mid-latitude North America via an interior ice-free corridor. Re-opening of the corridor less than 14 000 years ago indicates that the primary ancestors of living First Peoples, who already had spread widely in the Americas at this time, probably dispersed from the NW Pacific coast. A genetic 'arctic signal' in non-arctic First Peoples suggests that their parent population inhabited the GAP during the LGM, before their split from the former. We infer a shift from GAP terrestrial to a subarctic maritime economy on the southern BLB coast before dispersal in the Americas from the NW Pacific coast.

Dating the Paleolithic: Trapped charge methods and amino acid geochronology

Despite the vast array of different geochronological tools available, dating the Paleolithic remains one of the discipline’s greatest challenges. This review focuses on two different dating approaches: trapped charge and amino acid geochronology. While differing in their fundamental principles, both exploit time-dependent changes in signals found within crystals to generate a chronology for the material dated and hence, the associated deposits. Within each method, there is a diverse range of signals that can be analyzed, each covering different time ranges, applicable to different materials and suitable for different paleoenvironmental and archaeological contexts. This multiplicity of signals can at first sight appear confusing, but it is a fundamental strength of the techniques, allowing internal checks for consistency and providing more information than simply a chronology. For each technique, we present an overview of the basis for the time-dependent signals and the types of material that can be analyzed, with examples of their archaeological application, as well as their future potential.

Cirques of the Southeastern Tibetan Plateau and Their Links to Climatic and Non-Climatic Factors

Cirque morphology is used to reflect the patterns of paleoclimate, paleoglaciation, and landscape evolution. Cirque study has been conducted in the Gangdise Mountains of the southern Tibetan Plateau (TP) and the central TP (dominated by a weak Indian summer monsoon (ISM) or a continental climate). This study focused on the cirques in the southeastern TP, which is dominated by a strong ISM, to analyse the controlling factors on cirque morphology. A total of 361 cirques were mapped in the Taniantaweng Range of the southeastern TP, and their metrics were calculated. The results showed that the cirque sizes increased with temperature and decreased with precipitation, which may be due to the development of valley-type glaciers and the effect of non-climatic factors. The cirques tended to face NE, implying that they prefer leeward slopes, and they were under the 'morning-afternoon' effect. With altitude, the tendency of the cirque aspect shifted from N to SE, and the cirque size decreased. The former may indicate the ability of the high altitude to support cirque development on climatically unfavourable slopes; the latter may be due to the development of valley-type glaciers or insufficient space for cirque development. The cirque size and shape did not show statistical differences between aspects. The cirques on soft bedrocks had larger heights than those on hard bedrocks, indicating that soft bedrocks promote subglacial erosion. A comparison with the results of the western, central, and eastern sectors of the Gangdise Mountains and the central TP reveals that the strength of the ISM did not necessarily increase the cirque density but limited the cirque size on a regional scale. The CFA did not show a reverse relationship with precipitation, but it showed a positive correlation with the cirque Z_mean, which implies that the CFA was greatly affected by altitude, and its distribution does not always reflect paleoclimatic patterns.

A comprehensive review on performance, combustion and emissions of ternary and quaternary biodiesel/diesel blends

Global dependency and exhaustive usage of fossil fuels is leading to depletion of fossil fuel energy. The exponential rise in energy demand is an alarming sign; and added to that, emission generation, from burning of fossil fuel, has caused adverse effect on the environment. This paves the way in harvesting renewable energy options for a futuristic clean and healthy environment. The potentiality of biodiesel as an alternate energy option is well explored in past couple of decades. However with biodiesel, NO_x emissions as well as performance of engine from biodiesel is reported to be inferior to that of diesel owing to their inferior physical properties like density and viscosity. The mixture of biodiesels and different types of alcohols neutralizes the inferior property of blends. Ternary or quaternary blends of biodiesel have reported positive engine results. Initially, detailed study of different types of binary blends with respect to performance and emissions is done, trying to identify the research gap with the usage of binary mixture. The paper then dives into detailed study of ternary and quaternary blends with respect to performance, emission and combustion characteristics, trying to highlight different research outcomes.

Timing and dynamics of Late Wolstonian Substage 'Moreton Stadial' (MIS 6) glaciation in the English West Midlands, UK

Glaciation during the late Middle Pleistocene is widely recognized across continental northwest Europe, but its extent and palaeoenvironmental significance in the British Isles are disputed. Although glaciogenic sediments at Wolston, Warwickshire, in the English West Midlands, have been used to define the stratotype of the Wolstonian Stage, their age has been variably assigned between marine isotope stages (MIS) 12 and 6. Here we present sedimentological and stratigraphical observations from five sites across the English West Midlands whose chronology is constrained by new luminescence ages from glaciofluvial sediments, supplemented by cosmogenic ³⁶Cl exposure dating of erratic boulders. The ages suggest that between 199 ± 5 and 147 ± 2.5 ka the British Ice Sheet advanced into the English West Midlands as far south as Moreton-in-Marsh, Gloucestershire. This advance is assigned to the Moreton Stadial of the Late Wolstonian Substage. Dating of the glaciation to this substage allows correlation of the Moreton Stadial glacial deposits in the English West Midlands with those of the Drenthe Stadial during the Late Saalian Substage across continental northwest Europe.

Genetic evidence for post-glacial expansion from a southern refugium in the eastern moa (Emeus crassus)

Cycles of glacial expansion and contraction throughout the Pleistocene drove increases and decreases, respectively, in the geographical range and population size of many animal species. Genetic data have revealed that during glacial maxima the distribution of many Eurasian animals was restricted to small refugial areas, from which species expanded to reoccupy parts of their former range as the climate warmed. It has been suggested that the extinct eastern moa (Emeus crassus)-a large, flightless bird from New Zealand-behaved analogously during glacial maxima, possibly surviving only in a restricted area of lowland habitat in the southern South Island of New Zealand during the Last Glacial Maximum (LGM). However, previous studies have lacked the power and geographical sampling to explicitly test this hypothesis using genetic data. Here we analyse 46 ancient mitochondrial genomes from Late Pleistocene and Holocene bones of the eastern moa from across their post-LGM distribution. Our results are consistent with a post-LGM increase in the population size and genetic diversity of eastern moa. We also demonstrate that genetic diversity was higher in eastern moa from the southern extent of their range, supporting the hypothesis that they expanded from a single glacial refugium following the LGM.

The Late Middle Pleistocene mammalian fauna of Oumm Qatafa Cave, Judean Desert: taxonomy, taphonomy and palaeoenvironment

The Middle Pleistocene archaeological record of the southern Levant has proven key to understanding human evolution and intercontinental faunal biogeography. Knowledge of archaeological sites of that period in the southern Levant is biased, with most Middle Pleistocene localities in the Mediterranean areas in the north, despite the mosaic of environments that mark the entire region. A key Middle Pleistocene location in the Judean Desert - on the eastern margin of the Mediterranean zone - is the site of Oumm Qatafa, excavated in the early 1900s, which yielded a faunal collection spanning an estimated time period of 600-200 kya. Here, we present a revised taxonomy of the macromammalian fauna from the site, discuss the palaeoenvironmental implications of this assemblage, and relate the finds to other Pleistocene sites from the Levant. These data enable a more precise palaeoenvironmental reconstruction which attests to an open landscape, but with the addition of a mesic Mediterranean component close by. In addition, detailed taphonomic observations on butchery marks and Fourier transform infrared spectroscopy analysis of burnt bone link the fauna for the first time to anthropogenic activities in the cave.

Morphometric analyses of the vertebrae of Ambystoma (Tschudi, 1838) and the implications for identification of fossil salamanders

Ambystoma (Tschudi, 1838) represents a speciose clade of salamanders that are found across much of North America. Fossils referred to Ambystoma are reported from early Cenozoic deposits and are common in Quaternary fossil deposits. Most fossils identified as Ambystoma are isolated vertebrae. Both quantitative and qualitative characters were reported as being useful for identifying fossilized vertebrae of Ambystoma below the genus level. However, there is limited information on intraspecific variation in those characters and previous studies noted intracolumnar variation which affects the utility of those characters for fossil identification. A lack of understanding of variation in modern species of Ambystoma casts uncertainty on our ability to identify fossil vertebrae confidently. We aimed to document intraspecific and intracolumnar variation in vertebral morphology among species of Ambystoma and examine the implications for fossil identification. We assembled one of the largest skeletal datasets for Ambystoma and took linear measurements on 15 species. We used 2D geometric morphometric analyses to characterize atlantal shape variation in Ambystoma. We apply those morphometric data in a case study where we identify fossil vertebrae from Hall's Cave, a Quaternary fossil locality in central Texas. We found patterns of intraspecific and intracolumnar variation that have substantial implications for fossil identification. Classification accuracies for species and clades within Ambystoma varied considerably. Overall classification accuracies based on size adjusted measurements and 2D geometric morphometric landmarks were lower compared to classifications from non-size adjusted linear measurements and were similar to accuracies based on size adjusted linear measurements. We identified fossil vertebrae from our case study as likely belonging to the tiger salamander clade within Ambystoma, but found that some fossils with lower classification probabilities are of uncertain identity. We discuss biogeographic implications for our fossil identifications and comment on challenges and next steps for advancing our understanding of morphological variation in Ambystoma.

Photodynamic therapy characteristics of phthalocyanines in the presence of boron doped detonation nanodiamonds: Effect of symmetry and charge

The synthesis, photophysicochemical and photodynamic therapy (PDT) activity of benzothiazole substituted zinc phthalocyanine: 1 (asymmetrically substituted and composed of no charges), 2 (asymmetrically substituted and composed of three positive charges), and 3 (symmetrically substituted and composed of four positive charges), are presented. The triplet and singlet oxygen quantum yields were highest for complex 2 showing the importance of asymmetry and charge. The complexes are covalently and non-covalently linked to B doped detonation nanodiamonds (B@DNDs) to yield nanohybrids (B@DNDs-1, B@DNDs-2, B@DNDs-3). The presence of B@DNDs, asymmetry and positive charge resulted in improved PDT with the lowest cell viability being observed for B@DNDs-2 at 5%. The cell viability ranged from 5 to 7% for the nanohybrids compared to 19 to 26% for Pcs alone.

Zoogeographic significance of Dmanisi large mammal assemblage

We undertake a comparative mammalian zoogeographic analysis with the aim of revealing the extent to which the Dmanisi Early Pleistocene large mammal assemblage resembles, at the genus level, African, Arabian, and Eurasian localities of similar age. The inclusion of Old World Pliocene and Pleistocene mammalian faunas provides us with insights into the provincial origins of specific mammalian taxa and permits us to assess the relative affiliation of the Dmanisi mammalian faunas to other faunas in the Old World. Our analysis also allows us to consider hypotheses about the timing and direction of zoogeographic connections between western Eurasia and Africa during the Early Pleistocene. We utilize multiple zoogeographic analytical tools as a cross-comparison of Dmanisi with 42 other Eurasian and African mammalian-bearing localities between 2.7 and 0.7 Ma. Overall, we find that Dmanisi compares most closely with a subgroup of Greek, Italian, and Spanish localities that are slightly younger than Dmanisi itself. This could suggest a progressive dispersal from East to West of the large mammal communities during the late Early Pleistocene and the first occurrence at Dmanisi, and then later in Western Europe, of some taxa such as Stephanorhinus ex gr. etruscus-hundsheimensis, Equus altidens, Bison georgicus, Soergelia minor, Megantereon whitei, Canis borjgali, Canis (Xenocyon) lycaonoides. Dmanisi's habitats included drier areas, probably of open wooded savannah and grassland and by mountainous to semiarid rocky terrain. There is evidence that Dmanisi records short intervals of increased aridity in the middle part of the succession contemporaneous with the occurrence of Homo.

Comparative riverscape genomics of the rainbow darter (Etheostoma caeruleum) in glaciated and unglaciated environments

Periodic glaciation during the Quaternary period shaped the contemporary riverscape and distribution of freshwater fishes in the Mississippi River drainage of central North America. The rainbow darter (Etheostoma caeruleum) is a member of this ichthyofauna and has a disjunct distribution in glaciated and unglaciated environments west of the Mississippi River. Based on glacial history of the region, there are different expectations on the observed spatial genetic structure of populations in these environments. The aim of this study was to utilize genome-wide SNP data to compare the population genomic structure of the rainbow darter in river networks with disparate glacial histories; the Volga River in the glaciated upper Mississippi River basin and the Meramec River in the unglaciated Ozark Plateau. Individuals were sampled from localities within each river system at distances dictated by the organismal life history and habitat preferences. Riverscape analyses were performed on three datasets: total combined localities of both rivers and one for each river independently. The results revealed a lasting influence of historic glaciation on the population genomic structure of rainbow darter populations. There was evidence of population expansion into the glaciated northern region following glacial retreat. The population genetic signature within the Volga River did not fit expectations of the stream hierarchy model, but revealed a pattern of repeated colonization and extirpation due to cyclic glaciation. The population within the unglaciated Meramec River adhered to the stream hierarchy model, with a directional order of genetic diversity based on the life history and habitat preferences of the species. These results demonstrate the importance of considering the geologic and climatic history of a region as well as the life history of an organism when interpreting spatial genetic patterns.

A comparative study of the Early Pleistocene carnivore guild from Dmanisi (Georgia)

The carnivore guild of the Early Pleistocene site of Dmanisi is among the most diverse of the Early Pleistocene of the entire Old World. It includes 14 carnivoran taxa: Homotherium latidens, Megantereon whitei, Panthera onca georgica, Acinonyx pardinensis, Lynx issiodorensis; Pachycrocuta brevirostris; Canis (Xenocyon) lycaonoides, Canis borjgali, Vulpes alopecoides; Ursus etruscus; Lutra sp., Martes sp., Meles sp., and Pannonictis sp. The analysis of this rich carnivore guild was carried out under different methodological approaches to compare the assemblage with other chronological coeval European, Asian, and African sites from a paleobiological perspective. To achieve the goal, we used a permutational hierarchical method called boostrapping cluster analysis based on taxonomic absence/presence matrices (at both generic and specific level) and on ecological matrices (considering dietary preferences/hunting strategies of each carnivoran) and carried out Mantels tests assessing magnitude of time, space, ecology, and taxonomy as source of difference between guilds. Our results suggest a close similarity among the Dmanisi carnivore assemblage and other guilds recorded from European late Villafranchian sites such as Pirro Nord, Venta Micena, and Apollonia 1 and, in a lesser extent, to European Epivillafranchian sites as Vallonnet, Untermassfeld, or the Vallparadís Section. Early to Middle Pleistocene Asian carnivore assemblages display several similarities with the Dmanisi guild mainly in the record and diversity of felid and the canid ecomorphotypes. Eastern African sites such as Olduvai and Omo, as well as South African sites, display a lower similarity with the studied sample, basically for the most diverse hyenid taphocoenoses. To sum up, the present study suggests a close similarity between the Dmanisi carnivore guild and other European Late Early Pleistocene assemblages without close parallels with African or Asian assemblages.

Visual detection of binary, ternary and quaternary protein interactions in fission yeast using a Pil1 co-tethering assay

Protein-protein interactions are vital for executing nearly all cellular processes. To facilitate the detection of protein-protein interactions in living cells of the fission yeast Schizosaccharomyces pombe, here we present an efficient and convenient method termed the Pil1 co-tethering assay. In its basic form, we tether a bait protein to mCherry-tagged Pil1, which forms cortical filamentary structures, and examine whether a GFP-tagged prey protein colocalizes with the bait. We demonstrate that this assay is capable of detecting pairwise protein-protein interactions of cytosolic proteins and nuclear proteins. Furthermore, we show that this assay can be used for detecting not only binary protein-protein interactions, but also ternary and quaternary protein-protein interactions. Using this assay, we systematically characterized the protein-protein interactions in the Atg1 complex and in the phosphatidylinositol 3-kinase (PtdIns3K) complexes and found that Atg38 is incorporated into the PtdIns3K complex I via an Atg38-Vps34 interaction. Our data show that this assay is a useful and versatile tool and should be added to the routine toolbox of fission yeast researchers. This article has an associated First Person interview with the first author of the paper.

Review of the Early-Middle Pleistocene boundary and Marine Isotope Stage 19

The Global Boundary Stratotype Section and Point (GSSP) defining the base of the Chibanian Stage and Middle Pleistocene Subseries at the Chiba section, Japan, was ratified on January 17, 2020. Although this completed a process initiated by the International Union for Quaternary Research in 1973, the term Middle Pleistocene had been in use since the 1860s. The Chiba GSSP occurs immediately below the top of Marine Isotope Substage (MIS) 19c and has an astronomical age of 774.1 ka. The Matuyama-Brunhes paleomagnetic reversal has a directional midpoint just 1.1 m above the GSSP and serves as the primary guide to the boundary. This reversal lies within the Early-Middle Pleistocene transition and has long been favoured to mark the base of the Middle Pleistocene. MIS 19 occurs within an interval of low-amplitude orbital eccentricity and was triggered by an obliquity cycle. It spans two insolation peaks resulting from precession minima and has a duration of ~ 28 to 33 kyr. MIS 19c begins ~ 791-787.5 ka, includes full interglacial conditions which lasted for ~ 8-12.5 kyr, and ends with glacial inception at ~ 774-777 ka. This inception has left an array of climatostratigraphic signals close to the Early-Middle Pleistocene boundary. MIS 19b-a contains a series of three or four interstadials often with rectangular-shaped waveforms and marked by abrupt (< 200 year) transitions. Intervening stadials including the inception of glaciation are linked to the calving of ice sheets into the northern North Atlantic and consequent disruption of the Atlantic meridional overturning circulation (AMOC), which by means of the thermal bipolar seesaw caused phase-lagged warming events in the Antarctic. The coherence of stadial-interstadial oscillations during MIS 19b-a across the Asian-Pacific and North Atlantic-Mediterranean realms suggests AMOC-originated shifts in the Intertropical Convergence Zone and pacing by equatorial insolation forcing. Low-latitude monsoon dynamics appear to have amplified responses regionally although high-latitude teleconnections may also have played a role.

Effect of Using Different Chemical Dispersing Agents in Grain Size Analyses of Fluvial Sediments via Laser Diffraction Spectrometry

Laser diffraction spectrometry allows for efficiently obtaining high-resolution grain size data. However, pretreatment and dispersion of aggregates in sediment samples are essential pre-requisites for acquiring accurate results using this method. This study evaluates the effectiveness of five dispersing agents in deflocculating the investigated fluvial sediments and the resulting grain size distribution obtained by laser diffraction spectrometry. We also examine the ability of the different dispersing agents to deflocculate sediment samples treated by thermal combustion. Distilled water presented a low efficiency in deflocculating the samples and yielded a near-zero clay content for samples with an expected clay content. The other chemical dispersants were effective in dispersing aggregates and yielding clay, albeit with different efficiencies. Calgon had the highest dispersing ability, followed closely by sodium tripolyphosphate. The performance of chemical treatment with sodium oxalate approaches that of sodium tripolyphosphate. However, it leads to the formation of precipitates in the samples, obscuring the actual grain size data. Sodium pyrophosphate derived the least amount of deflocculation among the four chemical dispersants. Furthermore, all the chemical dispersants were found to be ineffective in dispersing aggregates in samples treated by thermal combustion.

The micro from mega: Dental calculus description and the first record of fossilized oral bacteria from an extinct proboscidean

OBJECTIVE

This study explores the chemical composition and surface aspects of fossilized dental calculus from the South American Quaternary proboscidean Notiomastodon platensis and the first record of fossilized oral bacteria from extinct megafauna.

MATERIALS

Blocks of dental calculus removed from the third molar of five specimens of Notiomastodon platensis collected from Brazil, Argentina, and Ecuador.

METHODS

We analyzed five samples of dental calculus by SEM and SEM-EDS, following a rigid protocol to avoid bacterial contamination.

RESULTS

The dental calculus surface is homogeneous, porous, with various crystals, and composed mainly by oxygen and calcium. One sample revealed a well-preserved mineralized biofilm, with several rods and cocci bacteria.

CONCLUSIONS

This is the first fossilized record of oral bacterial communities associated with extinct proboscideans.

SIGNIFICANCE

This record confirms the parasitism between oral bacteria and Notiomastodon platensis and will enable the study of paleogenomic aspects of oral microbiota of proboscideans.

LIMITATIONS

Fossilization conditions of proboscidean teeth with dental calculus are variable among specimens. Although rare, the preservation of oral bacteria is expected because of the oral biofilm composition.

Phylogenetics of mud snakes (Squamata: Serpentes: Homalopsidae): A paradox of both undescribed diversity and taxonomic inflation

Mud snakes (Serpentes: Homalopsidae) are a family of 55 described, mainly aquatic, species primarily distributed throughout mainland Southeast Asia and the Indo-Australian Archipelago. Although they have been the focus of prior research, the basic relationships amongst genera and species remain poorly known. We used a combined mitochondrial and nuclear gene dataset to infer their phylogenetic relationships, using the highest levels of taxon and geographic sampling for any homalopsid phylogeny to date (62% generic and 62% species coverage; 140 individuals). Our results recover two reciprocally monophyletic groups: the fangless Brachyorrhos and its sister clade comprised of all rear-fanged homalopsids. Most genera and interspecific relationships were monophyletic and strongly supported, but intergeneric relationships and intraspecific population structure lack support. We find evidence of both undescribed diversity as well as cases of taxonomic inflation within several species. Tree-based species delimitation approaches (mPTP) support potential new candidate species as distinct from their conspecifics and also suggest that many named taxa may not be distinct species. Divergence date estimation and lineage-through-time analyses indicate lower levels of speciation in the Eocene, with a subsequent burst in diversification in the Miocene. Homalopsids may have diversified most rapidly during the Pliocene and Pleistocene, possibly in relation to tectonic shifts and sea-level fluctuations that took place in Sundaland and the Sahul Shelf. Our analyses provide new insights on homalopsid taxonomy, a baseline phylogeny for the family, and further biogeographic implications demonstrating how dynamic tectonics and Quaternary sea level changes may have shaped a widespread, diverse family of snakes.

Insights Into the Significance of the Chinense Loess Plateau for Preserving Biodiversity From the Phylogeography of Speranskia tuberculata (Euphorbiaceae)

The significance of the Chinese Loess Plateau (CLP) in maintaining biodiversity for northern China has rarely been shown, as previous phylogeographic studies are mostly woody species and they have revealed that Quaternary refugia are mainly located in mountain regions. We selected a drought-enduring endemic herb, Speranskia tuberculata (Euphorbiaceae), to determine its glacial refugia and postglacial demographic history. To this end, we sampled 423 individuals from 38 populations covering its entire geographic distribution. Three chloroplast DNA (cpDNA) fragments, two low-copy nuclear genes, and six nuclear microsatellites (nSSRs) were used and supplemented with ecological niche modeling (ENM) to infer the phylogeographic history of this species. Populations with private haplotypes and high haplotype diversity of cpDNA are mainly located in the CLP or scattered around northeastern China and the coastal region. Spatial expansion, detected using a neutrality test and mismatch distribution, may have resulted in a widely distributed ancestral cpDNA haplotype, especially outside of the CLP. For nuclear DNA, private haplotypes are also distributed mainly in the CLP. In nSSRs, STRUCTURE clustering identified two genetic clusters, which are distributed in the west (western cluster) and east (eastern cluster), respectively. Many populations belonged, with little to no admixture, to the western cluster while (hardly) pure populations of the eastern cluster were barely found. Genetic differentiation is significantly correlated with geographic distance, although genetic diversity is uniformly distributed. ENM suggests that the distribution of S. tuberculata has recently expanded northwards from the southern CLP, whereas it has experienced habitat loss in the south. Thus, S. tuberculata populations probably survived the last glacial maximum (LGM) in the southern CLP and experienced post-glacial expansion. Wind-dispersed pollen could bring the majority of genotypes to the front during spatial expansion, resulting in uniformly distributed genetic diversity. Based on evidence from molecular data and vegetation and climate changes since the LGM, we conclude that drought-enduring species, especially herbaceous species, are likely to have persisted in the CLP during the LGM and to have experienced expansion to other regions in northern China.

Bone need not remain an elephant in the room for radiocarbon dating

Radiocarbon (¹⁴C) analysis of skeletal remains by accelerator mass spectrometry is an essential tool in multiple branches of science. However, bone ¹⁴C dating results can be inconsistent and not comparable due to disparate laboratory pretreatment protocols that remove contamination. And, pretreatments are rarely discussed or reported by end-users, making it an 'elephant in the room' for Quaternary scientists. Through a questionnaire survey, I quantified consensus on the reliability of collagen pretreatments for ¹⁴C dating across 132 experts (25 countries). I discovered that while more than 95% of the audience was wary of contamination and would avoid gelatinization alone (minimum pretreatment used by most ¹⁴C facilities), 52% asked laboratories to choose the pretreatment method for them, and 58% could not rank the reliability of at least one pretreatment. Ultrafiltration was highly popular, and purification by XAD resins seemed restricted to American researchers. Isolating and dating the amino acid hydroxyproline was perceived as the most reliable pretreatment, but is expensive, time-consuming and not widely available. Solid evidence supports that only molecular-level dating accommodates all known bone contaminants and guarantees complete removal of humic and fulvic acids and conservation substances, with three key areas of progress: (i) innovation and more funded research is required to develop affordable analytical chemistry that can handle low-mass samples of collagen amino acids, (ii) a certification agency overseeing dating-quality control is needed to enhance methodological reproducibility and dating accuracy among laboratories, and (iii) more cross-disciplinary work with better ¹⁴C reporting etiquette will promote the integration of ¹⁴C dating across disciplines. Those developments could conclude long-standing debates based on low-accuracy data used to build chronologies for animal domestications, human/megafauna extirpations and migrations, archaeology, palaeoecology, palaeontology and palaeoclimate models.

Radiocarbon Palaeolithic Europe database: A regularly updated dataset of the radiometric data regarding the Palaeolithic of Europe, Siberia included

At the Berlin INQUA Congress (1995) a working group, European Late Pleistocene Isotopic Stages 2 & 3: Humans, Their Ecology & Cultural Adaptations, was established under the direction of J. Renault-Miskovsky (Institut de Paléontologie humaine, Paris). One of the objectives was building a database of the human occupation of Europe during this period. The database has been enlarged and now includes Lower, Middle and Upper Palaeolithic sites connecting them to their environmental conditions and the available chronometric dating. From version 14 on, only sites with chronometric data were included.

In this database we have collected the available radiometric data from literature and from other more restricted databases. We try to incorporate newly published chronometric dates, collected from all kind of available publications. Only dates older than 9500 uncalibrated BP, correlated with a "cultural" level obtained by scientific excavations of European (Asian Russian Federation included) Palaeolithic sites, have been included. The dates are complemented with information related to cultural remains, stratigraphic, sedimentologic and palaeontologic information within a Microsoft Access database. For colleagues mainly interested in a list of all chronometric dates an Microsoft Excel list (with no details) is available (Tab. 1). A file, containing all sites with known coordinates, that can be opened for immediate use in Google Earth is available as a *.kmz file. It will give the possibility to introduce (by file open) in Google Earth the whole site list in "My Places".

The database, version 27 (first version was available in 2002), contains now 13,202 site forms, (most of them with their geographical coordinates), comprising 17,022 radiometric data: Conv. ¹⁴C and AMS ¹⁴C (13,144 items), TL (678 items), OSL (1050 items), ESR, Th/U and AAR (2150 items) from the Lower, Middle and Upper Palaeolithic. All ¹⁴C dates are conventional dates BP. This improved version 27 replaces the older version 26.

The Quaternary evolutionary history of Bristol rock cress (Arabis scabra, Brassicaceae), a Mediterranean element with an outpost in the north-western Atlantic region

BACKGROUND AND AIMS

Bristol rock cress is among the few plant species in the British Isles considered to have a Mediterranean-montane element. Spatiotemporal patterns of colonization of the British Isles since the last interglacial and after the Last Glacial Maximum (LGM) from mainland Europe are underexplored and have not yet included such floristic elements. Here we shed light on the evolutionary history of a relic and outpost metapopulation of Bristol rock cress in the south-western UK.

METHODS

Amplified fragment length polymorphisms (AFLPs) were used to identify distinct gene pools. Plastome assembly and respective phylogenetic analysis revealed the temporal context. Herbarium material was largely used to exemplify the value of collections to obtain a representative sampling covering the entire distribution range.

KEY RESULTS

The AFLPs recognized two distinct gene pools, with the Iberian Peninsula as the primary centre of genetic diversity and the origin of lineages expanding before and after the LGM towards mountain areas in France and Switzerland. No present-day lineages are older than 51 ky, which is in sharp contrast to the species stem group age of nearly 2 My, indicating severe extinction and bottlenecks throughout the Pleistocene. The British Isles were colonized after the LGM and feature high genetic diversity.

CONCLUSIONS

The short-lived perennial herb Arabis scabra, which is restricted to limestone, has expanded its distribution range after the LGM, following corridors within an open landscape, and may have reached the British Isles via the desiccated Celtic Sea at about 16 kya. This study may shed light on the origin of other rare and peculiar species co-occurring in limestone regions in the south-western British Isles.

Temperature change as a driver of spatial patterns and long-term trends in chironomid (Insecta: Diptera) diversity

Anthropogenic activities have led to a global decline in biodiversity, and monitoring studies indicate that both insect communities and wetland ecosystems are particularly affected. However, there is a need for long-term data (over centennial or millennial timescales) to better understand natural community dynamics and the processes that govern the observed trends. Chironomids (Insecta: Diptera: Chironomidae) are often the most abundant insects in lake ecosystems, sensitive to environmental change, and, because their larval exoskeleton head capsules preserve well in lake sediments, they provide a unique record of insect community dynamics through time. Here, we provide the results of a metadata analysis of chironomid diversity across a range of spatial and temporal scales. First, we analyse spatial trends in chironomid diversity using Northern Hemispheric data sets overall consisting of 837 lakes. Our results indicate that in most of our data sets, summer temperature (T_jul ) is strongly associated with spatial trends in modern-day chironomid diversity. We observe a strong increase in chironomid alpha diversity with increasing T_jul in regions with present-day T_jul between 2.5 and 14°C. In some areas with T_jul  > 14°C, chironomid diversity stabilizes or declines. Second, we demonstrate that the direction and amplitude of change in alpha diversity in a compilation of subfossil chironomid records spanning the last glacial-interglacial transition (~15,000-11,000 years ago) are similar to those observed in our modern data. A compilation of Holocene records shows that during phases when the amplitude of temperature change was small, site-specific factors had a greater influence on the chironomid fauna obscuring the chironomid diversity-temperature relationship. Our results imply expected overall chironomid diversity increases in colder regions such as the Arctic under sustained global warming, but with complex and not necessarily predictable responses for individual sites.

First report of Sus strozzii (Suidae, Mammalia) from the Early Pleistocene of Hungary (Dunaalmás) and species distinction based on deciduous teeth

Herein we describe a fragment of a mandible with a deciduous fourth premolar (dp4) from the Early Pleistocene locality of Dunaalmás, representing the first confirmed report of Sus strozzii from Hungary. The comparison of dp4 measurements supports a statistically significant distinction between S. strozzii and Sus scrofa. The two species overlap in time during the late Early Pleistocene of Europe (Epivillafranchian), but suid remains of this time-span are seldom classified at a species level. The correct taxonomic identification of the Epivillafranchian suids, which are often associated with evidences of hominin presence, is of great palaeoenvironmental value because S. scrofa and S. strozzii possess different ecological requirements.

All is flux: the predictive power of fluctuating Quaternary mammalian faunal-climate scenarios

The long-term impact of Middle and Late Pleistocene glacial-interglacial change led to the major reorganization of mammalian faunal communities in northern Europe through species origination, extinction, evolutionary change and distributional shifts. A Bray-Curtis cluster analysis with single linkage to examine relative faunal similarity was performed on mammalian assemblages from five successively older interglacials (MIS 1, 5e, 7c-a, 9 and 11) in Britain, a region with an exceptionally well-resolved faunal record for this time period. The results indicate a degree of continuity in terms of common interglacial elements occurring across all periods but also reveal that the particular climatic and environmental parameters of each interglacial resulted in the generation of very different faunal assemblages, depending on the length, intensity and structure of the interglacial. Of particular note are the comparability of the mammalian assemblages from warm interglacials MIS 5e and 9, and the high species diversity seen in MIS 7c-a, linked to relatively cool temperate conditions and the spread of dry grasslands. Together, these results offer insight into the overall 'predictability' of Quaternary mammalian interglacial community composition and what might be expected in the natural evolution of a Holocene interglacial freed of anthropogenic interference. This article is part of a discussion meeting issue 'The past is a foreign country: how much can the fossil record actually inform conservation?'

Quantitative data on latest-quaternary benthic foraminiferal assemblages in the South Evoikos Gulf semi-enclosed basin (central Aegean, Greece)

We herein present an original high-resolution dataset on the Late Pleistocene to Holocene (>15.17 ka BP) benthic foraminiferal record of two continuous sediment cores (DEH 5 and DEH 1), drilled from the shallow (max. depth ∼75 m) semi-enclosed basin of South Evoikos Gulf (central Aegean, Greece). Owing to its particular configuration, this marginal setting has been heavily affected by the latest-glacial to modern-interglacial sea-level and climate oscillations that left clear imprints on the benthic foraminiferal community. Our data comprise quantitative information of the downcore faunal distribution (raw species counts and relative abundances), diversity measurements, simplified datasets used for clustering analysis and calibrated age spans. This material can be efficiently utilized in any comparative or synthetic future study on the reconstruction of the latest-Quaternary palaeoceanographic (palaeobathymetric, sea-level) and palaeoenvironmental evolution of the Mediterranean shelf. The present data article is associated with the research article “Impact of latest-glacial to Holocene sea-level oscillations on central Aegean shelf ecosystems: A benthic foraminiferal palaeoenvironmental assessment of South Evoikos Gulf, Greece” by Louvari et al. (2019).

'At the crossroads towards polyploidy': genomic divergence and extent of homoploid hybridization are drivers for the formation of the ox-eye daisy polyploid complex (Leucanthemum, Compositae-Anthemideae)

Polyploidy plays a paramount role in phytodiversity, but the causes of this evolutionary pathway require further study. Here, we use phylogenetic methods to examine possible polyploidy-promoting factors by comparing diploid representatives of the comprehensive European polyploid complex Leucanthemum with members of its strictly diploid North African counterpart Rhodanthemum. We investigate genetic divergence and gene flow among all diploid lineages of both genera to evaluate the role of genomic differentiation and hybridization for polyploid speciation. To test whether hybridization in Leucanthemum has been triggered by the geological conditions during its diversification, we additionally generate a time-calibrated phylogeny of 46 species of the subtribe Leucantheminae. Leucanthemum shows a significantly higher genetic divergence and hybridization signal among diploid lineages compared with Rhodanthemum, in spite of a similar crown age and diversification pattern during the Quaternary. Our study demonstrates the importance of genetic differentiation among diploid progenitors and their concurrent affinity for natural hybridization for the formation of a polyploid complex. Furthermore, the role of climate-induced range overlaps on hybridization and polyploid speciation during the Quaternary is discussed.

Porosity, bulk density and CaCO3 content of travertines. A new dataset from Rapolano, Canino and Tivoli travertines (Italy)

The dataset presented in this article is used in the Quaternary Science Review research article "Evaluating the geogenic CO₂ flux from geothermal areas by analysing Quaternary travertine masses. New data from western Central Italy and review of previous CO₂ flux data" [1]. The present data article reports the physical properties and new compositional data of 86 travertine samples from Rapolano, Canino and Tivoli travertine deposits (Italy). The dataset include the following parameters: mass, volume, porosity, bulk density, CaCO₃ content and insoluble fraction. The dataset is integrated with the photographic documentation of the sampling areas, the location and the stratigraphic position of each sample.

Composition Dependence of Structural and Electronic Properties of Quaternary InGaNBi

To realize feasible band structure engineering and hence enhanced luminescence efficiency, InGaNBi is an attractive alloy which may be exploited in photonic devices of visible light and mid-infrared. In present study, the structural, electronic properties such as bandgap, spin-orbit splitting energy, and substrate strain of InGaNBi versus In and Bi compositions are studied by using first-principles calculations. The lattice parameters increase almost linearly with increasing In and Bi compositions. By bismuth doping, the quaternary InGaNBi bandgap could cover a wide energy range from 3.273 to 0.651 eV for Bi up to 9.375% and In up to 50%, corresponding to the wavelength range from 0.38-1.9 µm. The calculated spin-orbit splitting energy are about 0.220 eV for 3.125%, 0.360 eV for 6.25%, and 0.600 eV for 9.375% Bi, respectively. We have also shown the strain of InGaNBi on GaN; it indicates that through adjusting In and Bi compositions, InGaNBi can be designed on GaN with an acceptable strain.

Widespread global peatland establishment and persistence over the last 130,000 y

During the Holocene (11,600 y ago to present), northern peatlands accumulated significant C stocks over millennia. However, virtually nothing is known about peatlands that are no longer in the landscape, including ones formed prior to the Holocene: Where were they, when did they form, and why did they disappear? We used records of peatlands buried by mineral sediments for a reconstruction of peat-forming wetlands for the past 130,000 y. Northern peatlands expanded across high latitudes during warm periods and were buried during periods of glacial advance in northern latitudes. Thus, peat accumulation and burial represent a key long-term C storage mechanism in the Earth system.

Glacial−interglacial variations in CO₂ and methane in polar ice cores have been attributed, in part, to changes in global wetland extent, but the wetland distribution before the Last Glacial Maximum (LGM, 21 ka to 18 ka) remains virtually unknown. We present a study of global peatland extent and carbon (C) stocks through the last glacial cycle (130 ka to present) using a newly compiled database of 1,063 detailed stratigraphic records of peat deposits buried by mineral sediments, as well as a global peatland model. Quantitative agreement between modeling and observations shows extensive peat accumulation before the LGM in northern latitudes (>40°N), particularly during warmer periods including the last interglacial (130 ka to 116 ka, MIS 5e) and the interstadial (57 ka to 29 ka, MIS 3). During cooling periods of glacial advance and permafrost formation, the burial of northern peatlands by glaciers and mineral sediments decreased active peatland extent, thickness, and modeled C stocks by 70 to 90% from warmer times. Tropical peatland extent and C stocks show little temporal variation throughout the study period. While the increased burial of northern peats was correlated with cooling periods, the burial of tropical peat was predominately driven by changes in sea level and regional hydrology. Peat burial by mineral sediments represents a mechanism for long-term terrestrial C storage in the Earth system. These results show that northern peatlands accumulate significant C stocks during warmer times, indicating their potential for C sequestration during the warming Anthropocene.

Postcranial diversity and recent ecomorphic impoverishment of North American gray wolves

Recent advances in genomics and palaeontology have begun to unravel the complex evolutionary history of the gray wolf, Canis lupus Still, much of their phenotypic variation across time and space remains to be documented. We examined the limb morphology of the fossil and modern North American gray wolves from the late Quaternary (<ca 70 ka) to better understand their postcranial diversity through time. We found that the late-Pleistocene gray wolves were characterized by short-leggedness on both sides of the Cordilleran-Laurentide ice sheets, and that this trait survived well into the Holocene despite the collapse of Pleistocene megafauna and disappearance of the 'Beringian wolf' from Alaska. By contrast, extant populations in the Midwestern USA and northwestern North America are distinguished by their elongate limbs with long distal segments, which appear to have evolved during the Holocene possibly in response to a new level or type of prey depletion. One of the consequences of recent extirpation of the Plains (Canis lupus nubilus) and Mexican wolves (C. l. baileyi) from much of the USA is an unprecedented loss of postcranial diversity through removal of short-legged forms. Conservation of these wolves is thus critical to restoration of the ecophenotypic diversity and evolutionary potential of gray wolves in North America.

Late Quaternary environmental dynamics in Lenin Peak area (Pamir Mountains, Kyrgyzstan)

The Pamir Mountains include peaks exceeding 7000 m, such as Lenin Peak (7134 m) in the northern Zaalai Range. Here, we examine the distribution of soils and geomorphological processes and landforms in its northern slope, from the highest glaciated environments until Alai valley floor. We present the first geomorphological map of the study area as well as an accurate description the main geomorphological units in order to reconstruct landscape dynamics in the area from Quaternary cold stages until present-day. Five main units are distributed: (1) valley floor (2900-3040 m), an area that must have been ice-free during Quaternary glaciations and is currently being reshaped by glaciofluvial processes, with a large alluvial fan reworked by aeolian activity; (2) hummocky terrain (3040-3500 m) including two moraine systems left by a piedmont glacier during the Last Glaciation as well as hilly deposits originated by a catastrophic rockfall event; (3) U-shaped glacial valley (3500-3800 m), including some moraine ridges as well as a sedimentary cover composed of glacial till that is being eroded by fluvial and mass-wasting processes; (4) high mountain valleys (up to 4600-4800 m) adjacent to the main valley floor with small cirque and alpine glaciers and widespread periglacial processes in ice-free environments; (5) glaciers flowing from the Lenin Peak summit until the foot of the mountain, where they form a debris-covered (surge-type) glacier. The existence of abundant glacial, periglacial and rockfall deposits (moraines, till, erratic boulders) allows inferring five different environmental stages since the Last Glaciation. The latest glacial advances took place during the 20th century and the Little Ice Age and deposited two moraine systems near the glacial front. The occurrence of active rock glaciers and protalus lobes indicates that the limit of permafrost conditions is now located at 3400-3500 m, with seasonal frozen ground in lower areas.

Enhanced antioxidant and antifungal activity of chitosan derivatives bearing 6-O-imidazole-based quaternary ammonium salts

In this paper, a series of 6-O-imidazole-based quaternary ammonium chitosan derivatives via 6-O-chloroacetyl chitosan (CAClC) were successfully designed and synthesized. Detailed structural characterization was carried out by means of FT-IR and ¹H NMR spectroscopy, and elemental analysis. Furthermore, the antioxidant property against hydroxyl radicals, superoxide radicals, and DPPH radicals was evaluated in vitro. 2-(N,N,N-trimethyl)-6-O-(2-aminobenzimidazole)acetyl chitosan chloride (2NPhMC) and 2-(N,N,N-trimethyl)-6-O-(1-butylimidazole)acetyl chitosan chloride (NBMC) showed more than 90% scavenging indices at 1.6 mg/mL. Besides, the antifungal activity against Botrytis cinerea and Gibberella zeae was estimated using in vitro MIC and hypha measurements. Most of the quaternized chitosan derivatives especially with the long length alkyl chain and primary amino group showed an inhibitory index of > 85% at 1.0 mg/mL against Botrytis cinerea. Besides, the cytotoxicity of chitosan and all the quaternized chitosan derivatives was evaluated in vitro on HaCaT cells and all the quaternized chitosan derivatives bearing 6-O-imidazole exhibited low cytotoxicity. These results suggested that chitosan derivatives bearing 6-O-imidazole-based quaternary ammonium salts may be used as good biomaterials.

[Distribution changes and refugia of three spruce taxa since the last interglacial.]

Based on the current distribution information and 19 environmental variables data, we used the maximum entropy model to simulate the suitable distribution of Picea likiangensis var. likiangensis, P. purpurea and P. wilsonii in the last interglacial, Last Glacial Maximum, Mid- Holocene and present. The results from such modelling were validated by pollen data. We analyzed the relationship between species distribution dynamics and climate change, and then speculated the cryptic refugia of those species. Both the areas under the receiver operating characteristic curves and the verification results from pollen data indicated high accuracy of the model results. Results showed that isothermality was the most important factor influencing the distribution of P. likiangensis var. likiangensis and mean temperature of the warmest quarter was the most important for the distribution of both P. purpurea and P. wilsonii. Temperature was more important than precipitation in driving species distributions. Three species expanded their distribution ranges in Last Glacial Maximum due to their cold-adapted ecological habitat and the deep canyon topography feature which benefited their migration. There might be refugia of both P. wilsonii and P. purpurea in last interglacial, and they respectively located in Shennongjia Mountain in Hubei and Erlang Mountain and its nearby mountains in Sichuan. Our results, to some extent, made accurate prediction of the suitable distribution of three spruce species in the key periods since last interglacial, and speculated refugia of P. purpurea and P. willsonii. Our findings provided reference for better understanding of the formation mechanism of the present distribution of Picea and prediction of distribution changes in the future and sustainable management and protection of three spruce species.

Progressive aridification in East Africa over the last half million years and implications for human evolution

Evidence for Quaternary climate change in East Africa has been derived from outcrops on land and lake cores and from marine dust, leaf wax, and pollen records. These data have previously been used to evaluate the impact of climate change on hominin evolution, but correlations have proved to be difficult, given poor data continuity and the great distances between marine cores and terrestrial basins where fossil evidence is located. Here, we present continental coring evidence for progressive aridification since about 575 thousand years before present (ka), based on Lake Magadi (Kenya) sediments. This long-term drying trend was interrupted by many wet-dry cycles, with the greatest variability developing during times of high eccentricity-modulated precession. Intense aridification apparent in the Magadi record took place between 525 and 400 ka, with relatively persistent arid conditions after 350 ka and through to the present. Arid conditions in the Magadi Basin coincide with the Mid-Brunhes Event and overlap with mammalian extinctions in the South Kenya Rift between 500 and 400 ka. The 525 to 400 ka arid phase developed in the South Kenya Rift between the period when the last Acheulean tools are reported (at about 500 ka) and before the appearance of Middle Stone Age artifacts (by about 320 ka). Our data suggest that increasing Middle- to Late-Pleistocene aridification and environmental variability may have been drivers in the physical and cultural evolution of Homo sapiens in East Africa.

Short-tailed mice with a long fossil record: the genus Leggadina (Rodentia: Muridae) from the Quaternary of Queensland, Australia

The genus Leggadina (colloquially known as ‘short-tailed mice’) is a common component of Quaternary faunas of northeastern Australia. They represent a member of the Australian old endemic murid radiation that arrived on the continent sometime during the late Cenozoic. Here we describe two new species of extinct Leggadina from Quaternary cave deposits as well as additional material of the extinct Leggadina macrodonta. Leggadina irvini sp. nov. recovered from Middle-Upper (late) Pleistocene cave deposits near Chillagoe, northeastern Queensland, is the biggest member of the genus, being substantially larger than any other species so far described. Leggadina webbi sp. nov. from Middle Pleistocene cave deposits at Mount Etna, central eastern Queensland, shares features with the oldest species of the genus, the Early Pleistocene L. gregoriensis. Based on the current palaeoecological interpretation of the type locality, L. webbi, represents the only member of the genus that inhabited rainforest. The succession of Leggadina species through the late Quaternary suggests an ecological replacement of the extinct large-bodied L. irvini with the extant, small-bodied L. lakedownesis at Chillagoe. At Mt. Etna, the extinct rainforest species L. webbi is replaced with the extant xeric-adapted L. forresti during the latest Middle Pleistocene. This replacement is associated with a mid-Pleistocene shift towards progressive intensifying seasonal and arid climates. Our study adds to the growing list of small-bodied faunal extinctions during the late Quaternary of northern Australia.

How will climate novelty influence ecological forecasts? Using the Quaternary to assess future reliability

Future climates are projected to be highly novel relative to recent climates. Climate novelty challenges models that correlate ecological patterns to climate variables and then use these relationships to forecast ecological responses to future climate change. Here, we quantify the magnitude and ecological significance of future climate novelty by comparing it to novel climates over the past 21,000 years in North America. We then use relationships between model performance and climate novelty derived from the fossil pollen record from eastern North America to estimate the expected decrease in predictive skill of ecological forecasting models as future climate novelty increases. We show that, in the high emissions scenario (RCP 8.5) and by late 21st century, future climate novelty is similar to or higher than peak levels of climate novelty over the last 21,000 years. The accuracy of ecological forecasting models is projected to decline steadily over the coming decades in response to increasing climate novelty, although models that incorporate co-occurrences among species may retain somewhat higher predictive skill. In addition to quantifying future climate novelty in the context of late Quaternary climate change, this work underscores the challenges of making reliable forecasts to an increasingly novel future, while highlighting the need to assess potential avenues for improvement, such as increased reliance on geological analogs for future novel climates and improving existing models by pooling data through time and incorporating assemblage-level information.