Pleistocene Interglacial Periods Research Articles

A Class Project for Investigating Possible Future Local Effects of Global Climate Change through Student Analysis of Fossil Faunas

A common question posed to environmental scientists by nonscientists, particularly policymakers, is the following: In a world that is globally warmer, what will the new climate be like in specific geographical regions? This question has been and continues to be addressed by computer modeling, a technique that is out of reach for vast majority of students. However, an alternate approach to investigating this issue exists that is more practical for students. Past climates can be inferred for specific regions from fossils, utilizing climate tolerances of related modern organisms. When these inferred past climates correspond to periods of the Earth’s history where levels of carbon dioxide were as high or higher than today, these data can be used to extrapolate possible future local climates in a globally warmer world. The last Pleistocene interglacial period (known as the Eemian), which occurred approximately 120,000 years ago, is an ideal time period for studies of this kind for the following reasons. First, carbon dioxide levels were elevated at this time to levels approximating modern global conditions, and the world was warmer as evidenced by a much higher sea level than exists today. Secondly, most Eemian-age animals (especially mollusks) still exist, have known climate tolerances, and are relatively common as fossils. Students examining fossil mollusk faunas have applied this methodology to infer the Eemian climates of South Florida and coastal Virginia and found unexpectedly that for both regions the Eemian climate did not greatly differ from the modern one. The methodology described here can be used to address other important questions and puts such authentic and potentially valuable scientific research within practical reach of student scientists.

Late Acheulean Lithic Assemblages From Locality 010 at Gürgürbaba Hill (Eastern Anatolia)

The province of Van in north-eastern Turkey served as a land bridge between Africa and Eurasia during the Palaeolithic. The region is of particular relevance for understanding the movement of hominins between these continents. This study concerns the lithic remains from a locality at Gürgürbaba Hill, named Locality 010, north of the village of Ulupamir (Erciş district). Locality 010 was dated to 311±32 kya by terrestrial cosmogenic nuclides method, which coincides with Marine Isotope Stage 9 (MIS 9), a Middle Pleistocene interglacial period. The assemblage from this site is attributed to the Late Acheulean and resembles that of the southern Caucasus. This similarity indicates that the artefacts from Locality 010 were probably produced by late Lower Palaeolithic technology in a broad sense. These findings suggest local adaptations of late Middle Pleistocene hominins to high plateau environments.

How diverse can rare species be on the margins of genera distribution?

Different genetic patterns have been demonstrated for narrowly distributed taxa, many of them linking rarity to evolutionary history. Quite a few species in young genera are endemics and have several populations that present low variability, sometimes attributed to geographical isolation or dispersion processes. Assessing the genetic diversity and structure of such species may be important for protecting them and understanding their diversification history. In this study, we used microsatellite markers and plastid sequences to characterize the levels of genetic variation and population structure of two endemic and restricted species that grow in isolated areas on the margin of the distribution of their respective genera. Plastid and nuclear diversities were very low and weakly structured in their populations. Evolutionary scenarios for both species are compatible with open-field expansions during the Pleistocene interglacial periods and genetic variability supports founder effects to explain diversification. At present, both species are suffering from habitat loss and changes in the environment can lead these species towards extinction.

Genetic and morphological divergence at a biogeographic break in the beach-dwelling brooder Excirolana hirsuticauda Menzies (Crustacea, Peracarida)

BackgroundThere is a biogeographic break located at 30°S in the southeast Pacific, in a coastal area of strong environmental discontinuities. Several marine benthic taxa with restricted dispersal have a coincident phylogeographic break at 30°S, indicating that genetic structure is moulded by life history traits that limit gene flow and thereby promote divergence and speciation. In order to evaluate intraspecific divergence at this biogeographic break, we investigated the genetic and morphological variation of the directly developing beach isopod Excirolana hirsuticauda along 1900 km of the southeast Pacific coast, across 30°S.ResultsThe COI sequences and microsatellite data both identified a strong discontinuity between populations of E. hirsuticauda to the north and south of 30°S, and a second weaker phylogeographic break at approximately 35°S. The three genetic groups were evidenced by different past demographic and genetic diversity signatures, and were also clearly distinguished with microsatellite data clustering. The COI sequences established that the genetic divergence of E. hirsuticauda at 30°S started earlier than divergence at 35°. Additionally, the three groups have different past demographic signatures, with probable demographic expansion occurring earlier in the southern group (south of 35°S), associated with Pleistocene interglacial periods. Interestingly, body length, multivariate morphometric analyses, and the morphology of a fertilization-related morphological character in males, the appendix masculina, reinforced the three genetic groups detected with genetic data.ConclusionsThe degree of divergence of COI sequences, microsatellite data, and morphology was concordant and showed two geographic areas in which divergence was promoted at differing historical periods. Variation in the appendix masculina of males has probably promoted reproductive isolation. This variation together with gene flow restrictions promoted by life history traits, small body size, oceanographic discontinuities and sandy-beach habitat continuity, likely influenced species divergence at 30°S in the southeast Pacific coast. The degree of genetic and morphological differentiation of populations to the north and south of 30°S suggests that E. hirsuticauda harbours intraspecific divergence consistent with reproductive isolation and an advanced stage of speciation. The speciation process within E. hirsuticauda has been shaped by both restrictions to gene flow and a prezygotic reproductive barrier.

Ancient changes in the African tropics

Paleoecology Long-term records of past vegetation change are key to understanding how climate change affects ecosystems, but data are scarce—especially in highly biodiverse regions in the tropics. Lezine et al. present a detailed 90,000-year pollen core from an upland crater-lake site in the west African tropical montane forest, which is important from conservation and biogeographic standpoints. The upper treeline moved in response to climate change during the Pleistocene glacial and interglacial periods, whereas the lower limit of the Afromontane forest was stable. The constituent species of the forest also changed. This record resolves debates concerning the biogeographic history of Afromontane vegetation. Science , this issue p. [177][1] [1]: /lookup/doi/10.1126/science.aav6821

Relevance of ultrafine grains in the magnetic fabric of paleosols

The effects of pedogenic magnetic grains on the magnetic fabric of paleosols were investigated using samples from the Paks loess profile, Hungary. Rock magnetic experiments, electron probe microanalysis, and scanning electron microscopy revealed characteristic signatures of (post-)pedogenic influences on the original sedimentary fabric. No differences were observed between low- and high-frequency fabric, suggesting that the particle orientation distribution of superparamagnetic particles was isotropic or nearly isotropic. In some samples with low frequency dependence, the presence of superparamagnetic contributors was negligible compared to the coarser magnetic contributors. No inverse fabric was identified, indicating that stable single-domain magnetite had a negligible contribution to the fabric. Despite differences in the magnetic mineral content, the relative contributions of coarse and ultrafine grains appeared to be constant. Various methods of altering or preserving the sedimentary fabric during (post-)pedogenic processes were described. Some processes, such as the hydromorphic effect, weakened the anisotropy of the original fabric and strengthened the orientation of the grains. Meanwhile, other processes, such as post-burial, compaction of materials, and fragmentation, strengthened the foliation with increasing anisotropy. Processes that can fix the fabric and magnetic fabric of paleosols will allow us to use the fabric to determine the paleowind direction in the Pleistocene interglacial periods in future studies.

Genetic Pattern and Demographic History of Salminus brasiliensis: Population Expansion in the Pantanal Region during the Pleistocene.

Pleistocene climate changes were major historical events that impacted South American biodiversity. Although the effects of such changes are well-documented for several biomes, it is poorly known how these climate shifts affected the biodiversity of the Pantanal floodplain. Fish are one of the most diverse groups in the Pantanal floodplains and can be taken as a suitable biological model for reconstructing paleoenvironmental scenarios. To identify the effects of Pleistocene climate changes on Pantanal’s ichthyofauna, we used genetic data from multiple populations of a top-predator long-distance migratory fish, Salminus brasiliensis. We specifically investigated whether Pleistocene climate changes affected the demography of this species. If this was the case, we expected to find changes in population size over time. Thus, we assessed the genetic diversity of S. brasiliensis to trace the demographic history of nine populations from the Upper Paraguay basin, which includes the Pantanal floodplain, that form a single genetic group, employing approximate Bayesian computation (ABC) to test five scenarios: constant population, old expansion, old decline, old bottleneck following by recent expansion, and old expansion following by recent decline. Based on two mitochondrial DNA markers, our inferences from ABC analysis, the results of Bayesian skyline plot, the implications of star-like networks, and the patterns of genetic diversity (high haplotype diversity and low-to-moderate nucleotide diversity) indicated a sudden population expansion. ABC allowed us to make strong quantitative inferences about the demographic history of S. brasiliensis. We estimated a small ancestral population size that underwent a drastic fivefold expansion, probably associated with the colonization of newly formed habitats. The estimated time of this expansion was consistent with a humid and warm phase as inferred by speleothem growth phases and travertine records during Pleistocene interglacial periods. The strong concordance between our genetic inferences and this historical data could represent the first genetic record of a humid and warm phase in the Pantanal in the period since the Last Interglacial to 40 ka.

A strengthened East Asian Summer Monsoon during Pliocene warmth: Evidence from ‘red clay’ sediments at Pianguan, northern China

The Pliocene epoch (5.3–2.6 Ma) is the most recent geological interval in which atmospheric CO2 levels were similar to those of the present day (∼400 ppmv). This epoch is therefore considered to be the best ancient analog for predicting a future anthropogenic greenhouse world. In order to determine the response of the East Asian Summer Monsoon (EASM) rainbelt during Pliocene warmth, a 71.9 m-thick aeolian ‘red clay’ sequence at Pianguan was investigated. Rock magnetic experiments suggest that magnetite of pseudo-single domain size is the dominant remanence carrier in the ‘red clay’ sequence. Magnetostratigraphic data, constrained by lithostratigraphy, show that the polarity zones of the ‘red clay’ section correlate with those between subchrons C2An.2r and C3An.2n of the geomagnetic polarity time scale (GPTS), yielding an age range of 6.9–2.9 Ma. The ‘red clay’ deposits exhibit enhanced weathering intensity over two time intervals, namely 5.23–4.3 Ma and 3.7–2.9 Ma, as evidenced by their well-developed pedogenic characteristics, as well as their high free to total Fe2O3 ratios and high redness (a∗) values, which in turn indicate an increased summer monsoon intensity during most of the Pliocene. Furthermore, the pedogenic characteristics of the well-weathered Pliocene soils were compared with those of paleosol unit S5 (one of the best-developed soil units found in Pleistocene loess) from the Yulin, Luochuan and Lantian sections, which constitute a north-south transect across the Chinese Loess Plateau (CLP). The Pliocene soils at Pianguan show a pedogenic development similar to the S5 (∼0.5 Ma) at Luochuan in the central Plateau, which is located some 3.7° latitude south of Pianguan, but this development is much stronger than that observed at Yulin in the north, and weaker than that seen at Lantian in the south. This may imply a more northerly penetration (∼400 km) of the monsoon rainbelt during Pliocene warmth compared with the Pleistocene interglacial period (∼0.5 Ma ago), supporting the prediction that the EASM rainbelt shifts northward in a warmer world. In addition, our results show that Pliocene warmth was unlikely to have been characterized by a permanent El Niño-like state, but was possibly influenced by a La Niña-like state.

An intertropical opossum (Mammalia, Marsupialia, Didelphidae) from the late Middle–Late Pleistocene of austral South America

The record of an opossum is reported here coming from a Middle–Late Pleistocene fluvial sedimentary sequence outcropping in the austral Chaco geomorphological region, Santa Fe province. Despite this family has different living forms widely distributed in South American plains, with great tolerance to diverse habitats conditions, the Pleistocene occurrence of didelphoids is very scarce and only limited to Holocene deposits sensu lato from austral pampean plains. The specimen found represents at the moment the only Pleistocene didelphoid opossum from Argentina with an accurate stratigraphical context. In a taphonomic framework, MFA-Pv 1582 shows no evidence of abrasion produced by transport, probably resulting of a very short time-transport. This intertropical form of Didelphis genus from Pleistocene sequences displays undoubtedly novel and sustancial paleoenvironmental and ecomorphological conditions to test in the austral Chaco region. Although the specimen shares a generalized didelphoid form, some morphologies in the humerus are closer with arboreal habits. In this context, added to the sedimentological and stratigraphical framework, it’s possible to suggest that subtropical conditions with some woodlands and wetlands dominate the provenance region of the fossil material, over a late Middle–Late Pleistocene interglacial period.

Pleistocene to holocene expansion of the black-belt cichlid in Central America, Vieja maculicauda (Teleostei: Cichlidae).

The distributions of many Northern Hemisphere organisms have been influenced by fluctuations in sea level and climatic conditions during Pleistocene interglacial periods. These cycles are associated with range contraction and refugia for northern-distributed organisms as a response to glaciers. However, lower sea levels in the tropics and sub-tropics created available habitat for expansion of the ranges of freshwater organisms. The goal of this study was to use ecological niche modeling to test the hypothesis of north to south range expansion of Vieja maculicauda associated with Pleistocene glacial cycles. Understanding the biogeography of this widespread species may help us better understand the geology and interconnectivity of Central American freshwaters. Occurrence data for V. maculicauda was based on georeferencing of all museum records of specimens recovered from FishNet2. General patterns of phylogeographic structure were assessed with mtDNA. Present day niche models were generated and subsequently projected onto paleoclimatic maps of the region during the Last Interglacial, Last Glacial Maximum, and mid-Holocene. Phylogenetic analysis of mtDNA sequence data showed no phylogeographic structure throughout the range of this widespread species. Present day niche models were congruent with the observed distribution of V. maculicauda in Central America. Results showed a lack of suitable freshwater habitat in northern Central America and Mexico during the Last Interglacial, with greatest range expansion during the Last Glacial Maximum and mid-Holocene. Results support the hypothesis of a north to south range expansion of V. maculicauda associated with glacial cycles. The wide distribution of this species compared to other closely related cichlids indicates the latter did not respond to the degree of V. maculicauda in expansion of their distributions. Future work aimed at comparisons with other species and modeling of future climatic scenarios will be a fruitful area of investigation.

Neogene carbonate platform development in the NW South China Sea: Litho-, bio- and chemo-stratigraphic evidence

The variations of lithostratigraphy, foraminifera, geochemical elements, and organic biomarkers in well XK1 from the Xisha (Paracel) Islands reveal the history of carbonate platform development since the early Miocene in the South China Sea. Our results indicate that reef growth was more active in the middle Miocene than in any earlier periods, decreased in the late Miocene, revitalized in the Pliocene, and active again in the Pleistocene interglacial periods. Unlike those limestone-rich intervals, the late Miocene succession in well XK1 is characterized by dolomitized limestones with a low deposition rate (30–60m/Ma post-compaction). These late Miocene rocks also contain relative high MgO (~20%), more ∑REE, abundant algae and some small sized foraminifera, but rare larger benthic foraminifera, very low land-sourced brGDGTs (0–0.5ng/20g), low BIT index (0.1–0.5), and low TEX86-derived sea temperature (~20–25°C), indicating limited active reef growth in relative cooler mesophotic environments at >30m water depths. Similar dolomitized limestones of late Miocene age also occur in other carbonate platform areas including the Nansha (Spratly) Islands in the southern South China Sea. Together, these South China Sea records provide regional evidence of a recession in global carbonate platform development starting from the late Miocene. While carbonate platform reduction in other regions may have been triggered by global cooling and changing oceanic chemistry, accelerated basin subsidence coupled with monsoon cooling are considered as the main factors causing the reef decline in the late Miocene South China Sea.

Middle Pleistocene molluscan fauna from the Valle Giumentina (Abruzzo, Central Italy): Palaeoenvironmental, biostratigraphical and biogeographical implications

Abstract Palaeoenvironmental reconstructions through the Middle Pleistocene sequence in the Valle Giumentina, located in the Abruzzo region of Central Italy, are discussed. The sampled sequence is 16 m thick and includes nine levels with Lower Palaeolithic industries. The lithostratigraphy shows fluvio-glacial sediments with interbedded colluvial deposits and volcanic tephras. Fine sediments are composed of calcareous sands and silts, most of them yielding well-preserved mollusc shells. Forty-five samples, at 10 cm resolution, yielded 45 taxa, which could be assigned to four biozones. The oldest (biozone VGM1) indicate an open environment, which becomes a closed forest landscape developing under temperate conditions (VGM2). After a decline of thermophilous species (VGM3), mollusc assemblages indicate a dry open environment typical of a glacial period (VGM4). All prehistoric occupation horizons occur during stable environmental episodes but under both temperate and cold climatic conditions. The molluscan succession is allocated to the Middle Pleistocene on the basis of the occurrence of Jaminia malatestae, a well-known Italian species, now extinct, as well as the similarity of the molluscan record to that of Case Picconetto, a well-dated site nearby. This attribution is supported by three tephra layers dated by 40Ar/39Ar at 556 ± 6, 531 ± 5 and 456 ± 2 ka. The sequence is correlated with marine isotopic stages 14, 13 and 12. Four species of land snail (Azeca goodalli, Ruthenica filograna, Pagodulina pagodula, Nesovitrea hammonis) occur beyond their modern range and are therefore of biogeographical interest. These snails are western and central European in origin and their presence within the Valle Giumentina deposits highlight a north-south gradient of colonization during Pleistocene interglacial periods.

Carbon isotope offsets between benthic foraminifer species of the genus Cibicides (Cibicidoides) in the glacial sub‐Antarctic Atlantic

AbstractEpibenthic foraminifer δ13C measurements are valuable for reconstructing past bottom water dissolved inorganic carbon δ13C (δ13CDIC), which are used to infer global ocean circulation patterns. Epibenthic δ13C, however, may also reflect the influence of 13C‐depleted phytodetritus, microhabitat changes, and/or variations in carbonate ion concentrations. Here we compare the δ13C of two benthic foraminifer species, Cibicides kullenbergi and Cibicides wuellerstorfi, and their morphotypes, in three sub‐Antarctic Atlantic sediment cores over several glacial‐interglacial transitions. These species are commonly assumed to be epibenthic, living above or directly below the sediment‐water interface. While this might be consistent with the small δ13C offset that we observe between these species during late Pleistocene interglacial periods (Δδ13C = −0.19 ± 0.31‰, N = 63), it is more difficult to reconcile with the significant δ13C offset that is found between these species during glacial periods (Δδ13C = −0.76 ± 0.44‰, N = 44). We test possible scenarios by analyzing Uvigerina spp. δ13C and benthic foraminifer abundances: (1) C. kullenbergi δ13C is biased to light values either due to microhabitat shifts or phytodetritus effects and (2) C. wuellerstorfi δ13C is biased to heavy values, relative to long‐term average conditions, for instance by recording the sporadic occurrence of less depleted deepwater δ13CDIC. Neither of these scenarios can be ruled out unequivocally. However, our findings emphasize that supposedly epibenthic foraminifer δ13C in the sub‐Antarctic Atlantic may reflect several factors rather than being solely a function of bottom water δ13CDIC. This could have a direct bearing on the interpretation of extremely light South Atlantic δ13C values at the Last Glacial Maximum.

MIS 11-locality of Medzhibozh, Ukraine: Archaeological and paleozoological evidence

The Lower Paleolithic localities near the town of Medzhibozh in the Khmelnitsky region of western Ukraine represent a group of multilayered sites near the Southern Bug River. Medzhibozh 1 locality is the focus of the presented report. The age of its main assemblage is defined at the beginning of the Zavadovka episode, MIS 11, while the underlying sediments are likely dated to Lubny time, MIS 13–15. Both assemblages contain lithic artefacts. The more recent is accompanied with rich fauna remains and presumable traces of hearths.The list of large mammalian fauna from Medzhibozh 1 (NISP = 450) revealed the presence of few carnivores (Ursus deningeri and Ursus thibetanus) and the dominance of cervids (Cervus elaphus, Dama dama clactoniana and Capreolus suessenbornensis) associated with Sus scrofa, Stephanorhinus kirchbergensis and Castor fiber. This provides evidence for a temperate climate as well confirms the biochronological attribution, as the fauna correspond to those typically associated to middle Pleistocene interglacial periods. It also fits well with the humid and forest environment described from the microfauna and shell analysis.From an archaeological point of view, assemblages of Medzhibozh 1 could be adequately defined as belonging to the industries of technological Mode 1 (Oldowan). The material cultural horizons, despite the relatively late age (about 0.4–0.5 Ma), are characterized by the predominance of choppers, chopping tools, and isolated retouched flakes, as well as few knapped flakes, and broken and fragmented pieces of various raw materials showing minimum secondary working. Available inventories contain no good instances of core knapping, as well as almost no morphologically stable shaping of flake tools and no signs of bifacial technology. Long bones of deer are characterized by systematic intentional breakage with percussion cones and cut-marks. Complementary species like rhinoceros, wild boar, or bears are represented by incomplete skeletons. Rhinoceros and bear bones showed evidence of long and deep cut-marks. Carnivore activity is rare. Burnt bones are well documented and are associated with charcoals and heated sediments. The Medzhibozh studies are directly relevant to the study and reconstruction of ancient migration paths on the territory of North-Western Eurasia, in its East European segment.

Changing nature of Pleistocene interglacials - is it recorded by paleosoils in Hungary (Central Europe)?

Based on stable isotope analyses of worldwide reference curves, it has long been apparent that duration, intensity and climatic conditions of Pleistocene interglacial periods were significantly diverse. As a consequence of negligible fresh, detrital material admixture during interglacials, the soil formation intensity and maturity of various kinds of past soils have been holding vital information on the environmental conditions at the time the soils formed. This, in turn, means that several physicochemical properties of soils allow us to reconstruct past climatic regimes. Loess-paleosol sequences in Hungary (Central Europe) provide insight into the cyclic nature of glacial-interglacial variations of the last 1 million years. The paleosoils have been recognized as the product of warmer and moister interglacials, when the (glacial) loess material was altered by chemical weathering and pedogenic processes. The gradual change from oldest red Mediterranean soils via forest and forest-steppe soils to steppe soils represents well the continuous decrease of chemical alteration of interglacial paleosoils determined by environmental factors and duration of soil formation. Pedogene units from MIS-21 to MIS-5 strata were analysed in the course of this study. Major element analyses were carried out to get a proper picture on the paleoenvironmental conditions. Geochemical transfer functions have been applied to derive mean annual precipitation and mean annual temperature. These kinds of quantitative data on past climate and the stratigraphic data allow us to fit our pedostratigraphic units into a global context. The present paper is aimed at providing new information on the various climatic and environmental characteristics of Pleistocene interglacial periods and soil forming processes.

Carbonate features in the uppermost layers of Quaternary deposits, Northern Armenia, and their significance for paleoenvironmental reconstruction

Recent archaeological studies in the Lori Depression of Armenia (Lesser Caucasus) revealed a series of multilevel Early Paleolithic (Acheulian) sites belonging to the Early-Middle Pleistocene stage of occupation of the Caucasus. In the uppermost layers of these sites, the paleosols and sediments contain carbonate features (CFs) whereas the lower layers are absolutely free from carbonates. The aim of this work is to examine the role of detected CFs as an indicator for reconstructions of the Early-Middle Pleistocene paleoenvironments, to determine the source, time and conditions of carbonates' accumulation in initially non-calcareous and high-degree weathered humid paleosols. Three sections were studied: Kurtan I, points 1–2 and Muradovo. There are different forms of CFs represented by the calcified root cells in the layer 1, the hard nodules in the layer 2 and the laminae-like carbonates in the layer 3 of the sites studied. All the CFs are of the aqueous (hydrogenic) origin. The CFs of the uppermost layers 1 and 2 in the Kurtan I, point 2 were accumulated in the Holocene lake. The calcified root cells were formed on the swamp shore whereas the hard nodules on the lake bottom under stagnant water. The laminae-like carbonates in the layer 3 were accumulated in the Kurtan I and Muradovo sections due to strong erosion cycle(s) in the Late Pleistocene interglacial period(s) that led to the limestone scour in the region by ground and surface water. They reflect the earliest stage of the allochthonous carbonate accumulation in the area dated by radiocarbon method to approximately 20 ka cal BP. Therefore, all the CFs cannot be regarded as indicative of Early and Middle Pleistocene environmental changes, as they appeared in the uppermost layers of the studied sections much later than the time of formation for the surrounding groundmass.

Quaternary perspectives on the diversity of land snail assemblages from northwestern Europe

The land snail assemblages in NW Europe exhibit marked gradients in diversity related to both latitude and longitude. These gradients, in turn, are linked to regional differences in temperature and moisture, although other non-climatic factors may be involved. Such diversity patterns have been described for the modern land snail faunas of NW Europe, especially those that inhabit forest. Here we provide an historical perspective on the development and composition of comparable land snail assemblages from various interglacials from the Middle and Late Pleistocene, and from the Holocene. We review the land snail assemblages from tufa sequences, which provide the best faunal records for each of the temperate periods. Data from 32 Quaternary sites in 7 NW European countries are considered. Assemblages from ‘forest optima’ of Pleistocene interglacial periods are richer in species compared with those from the Holocene. Correspondence analysis (CA) of data from 25 Quaternary sites in the regions where both Pleistocene and Holocene sites occur (i.e. southern England, northern France and Germany) resulted in a geographical separation of the assemblages into a western and eastern group. CA on each geographical group resulted in chronological divisions separating Pleistocene sites from the Holocene sequences. This separation results from the occurrence of numerous Central and Eastern European species in the Pleistocene faunas, whereas Holocene assemblages are characterized by species with mostly Western and Northern European modern ranges. This difference appears to reflect climatic influences, rather than resulting from anthropogenic effects. CA of 19 Holocene tufas produced geographical clusters clearly related to their position on a west-east gradient, presumably linked to some effect of ‘continentality’. During the mid Holocene, the diversity of forest snails from tufas in southern England exceeded the totals from the richest calcareous woodland sites in the region today. Further work is needed to establish whether this pattern holds for other regions of NW Europe.

Interglacial microrefugia and diversification of a cactus species complex: phylogeography and palaeodistributional reconstructions for Pilosocereus aurisetus and allies.

The role of Pleistocene climate changes in promoting evolutionary diversification in global biota is well documented, but the great majority of data regarding this subject come from North America and Europe, which were greatly affected by glaciation. The effects of Pleistocene changes on cold- and/or dry-adapted species in tropical areas where glaciers were not present remain sparsely investigated. Many such species are restricted to small areas surrounded by unfavourable habitats, which may represent potential interglacial microrefugia. Here, we analysed the phylogeographic structure and diversification history of seven cactus species in the Pilosocereus aurisetus complex that are restricted to rocky areas with high diversity and endemism within the Neotropical savannas of eastern South America. We combined palaeodistributional estimates with standard phylogeographic approaches based on two chloroplast DNA regions (trnT-trnL and trnS-trnG), exon 1 of the nuclear gene PhyC and 10 nuclear microsatellite loci. Our analyses revealed a phylogeographic history marked by multiple levels of distributional fragmentation, isolation leading to allopatric differentiation and secondary contact among divergent lineages within the complex. Diversification and demographic events appear to have been affected by the Quaternary climatic cycles as a result of isolation in multiple patches of xerophytic vegetation. These small patches presently harbouring P.aurisetus populations seem to operate as microrefugia, both at present and during Pleistocene interglacial periods; the role of such microrefugia should be explored and analysed in greater detail.

The application of isotope and chemical analyses in managing transboundary groundwater resources

Managing transboundary groundwater resources requires accurate and detailed knowledge of aquifers and groundwater bodies. The Pannonian Basin is the largest intracontinental basin in Europe with a continuous succession of more than 7km of Miocene to Quaternary sediments and with an average geothermal gradient of about 5°C/100m. Geographically the Pannonian basin overlaps eight countries (Hungary, Romania, Serbia, Croatia, Slovenia, Austria, Slovakia and Ukraine), so the issue of transboundary cold and thermal water resources is regionally very important. The T-JAM bilateral Hungarian–Slovenian (HU–SLO) project is the first to apply modern isotopic and chemical analyses in the characterization and correlation of a number of shared groundwater resources in the Mura-Zala Sub-basin of the Pannonian. The aims of this work were the identification of groundwater flow paths, the delineation of transboundary aquifers based on thermal and cold groundwater geochemical and isotope properties in the Mura-Zala Basin, and providing input to calibrate a hydraulic numerical model. Following a common groundwater sampling campaign, 24 cold and thermal groundwater samples from seven aquifers were collected for chemical, isotope, gas and noble gas analyses. Chemical analyses, and D, O and C isotopes were used to correlate cross border aquifers. A regional groundwater flow is hydrogeologically possible in some aquifers in the Mura-Zala Basin, and has been confirmed by hydrogeochemistry. The Újfalu (HU) and Mura (SLO) Formations are a part of the active regional thermal groundwater flow system, probably hydraulically separated from the shallower flow system of the Ptuj-Grad (SLO), Zagyva and Somló-Tihany (HU) Formations. The thermal water is of meteoric origin, reductive and alkaline. The predominant water type in the Quaternary and Pliocene aquifers is Ca–Mg–HCO3, changing to Na–HCO3 in the main Pannonian geothermal aquifer, and Na–Cl brine in deeper and older Miocene aquifers. Total dissolved solids and Na content generally increase with depth. Deuterium is in the range −87‰ to −75‰, 18O from −11.9‰ to −10.4‰, while 14C values are less than 6.1pmC in the samples of the active regional thermal groundwater flow system. These and results of noble gas analyses indicate recharge during the Pleistocene interglacial period with temperatures around 6–7°C. Regional thermal water resources are limited and environmental isotopes can be used as an early warning in the management of thermal water.

Genetic structure of the Delphinium naviculare species group tracks Pleistocene climatic oscillations in the Tianshan Mountains, arid Central Asia

Pleistocene climatic fluctuations have affected the evolution of the genetic structure of many organisms. In this study, we test the hypothesis that glacial–interglacial cycles are traceable from genetic footprints retained within plant species. Fourteen populations belonging to the Delphinium naviculare species group were sampled from the Tianshan Mountains in western China, and 14 genotypes were detected based on sequences of the two chloroplast fragments trnS–trnG and trnL–trnF. A Bayesian relaxed molecular clock approach revealed that genetic divergence in this species group began in the early Pleistocene and intensified during mid-Pleistocene. A lineage-through-time (LTT) plot shows dramatic accumulations of Delphinium lineages during the three Pleistocene interglacial periods in this area. From ecological niche modeling (ENM), it appears that the distribution of the species group most likely shrunk in the eastern arid and southwestern high-altitude parts of its range during the Last Glacial Maximum (LGM), suggesting that cold and drought were primary drivers of lineage migration during glacial periods. Humid valleys at mid-elevation served as refugia at these times; however, during the latest two glacial epochs, new refugia likely appeared, corresponding to a decreased extent of glaciation. In accordance with the glacial chronology derived from many proxy data such as glacial tills, lacustrine sedimentary sequences, and oxygen isotope records, the genetic structure of the D. naviculare species group reveals a paleoclimatic history that is able to differentiate three glacial–interglacial cycles and an overall trend towards aridity during the course of the Pleistocene.