Pliocene-Pleistocene stack of globally distributed benthic stable oxygen isotope records

We present a 5.3-Myr stack (the ''LR04'' stack) of benthic d18O records from 57 globally distributed sites aligned by an automated graphic correlation algorithm. This is the first benthic delta18O stack composed of more than three records to extend beyond 850 ka, and we use its improved signal quality to identify 24 new marine isotope stages in the early Pliocene. We also present a new LR04 age model for the Pliocene-Pleistocene derived from tuning the delta18O stack to a simple ice model based on 21 June insolation at 65 N. Stacked sedimentation rates provide additional age model constraints to prevent overtuning. Despite a conservative tuning strategy, the LR04 benthic stack exhibits significant coherency with insolation in the obliquity band throughout the entire 5.3 Myr and in the precession band for more than half of the record. The LR04 stack contains significantly more variance in benthic delta18O than previously published stacks of the late Pleistocene as the result of higher resolution records, a better alignment technique, and a greater percentage of records from the Atlantic. Finally, the relative phases of the stack's 41- and 23-kyr components suggest that the precession component of delta18O from 2.7-1.6 Ma is primarily a deep-water temperature signal and that the phase of d18O precession response changed suddenly at 1.6 Ma.

(Table 1) Age and sedimentation rates of Pleistocene/Holocene sequences at DSDP Sites 86-580 and 94-611

The recovery from the North Atlantic (Site 611) of a continuous Pleistocene sedimentary record with a siliceous microfaunal component made it possible to compare the high-latitude abundance pattern of the radiolarian species Cycladophora davisiana in the Atlantic with that produced from analyses of a high-latitude record (Site 580) from the northwest Pacific. Previous studies had shown that the late Pleistocene (0-0.45 Ma) abundance variations of this species in these high-latitude regions were similar. Cycladophora davisiana maxima in the North Atlantic record reach abundance levels three to four times higher than C. davisiana maxima registered in sediments from the northwest Pacific site. This difference in magnitude of abundance peaks is most likely an effect of the more northerly location of Site 611 (53°N) compared with that of Site 580 (42°N), since high-latitude time-slice studies have shown a direct relationship between increasing latitude and C. davisiana abundance. Discontinuous preservation of radiolarians in sediments from North Atlantic Site 611 allows only tentative correlation of the North Atlantic and northwest Pacific C. davisiana abundance curves. These correlations are confined to those portions of the cores where ages are tightly constrained by magnetic boundaries, and to intervals with comparable sedimentation rates.

The late Pliocene pollen record of ODP Site 108-658 off Cape Blanc, Atlantic Ocean

A 200 m long marine pollen record from ODP Site 658 (21°N, 19°W) reveals cyclic fluctuations in vegetation and continental climate in northwestern Africa from 3.7 to 1.7 Ma. These cycles parallel oxygen isotope stages. Prior to 3.5 Ma, the distribution of tropical forests and mangrove swamps reached Cape Blanc, 5°N of the present distribution. Between 3.5 and 2.6 Ma, forests occurred at this latitude during irregular intervals and nearly disappeared afterwards. Likewise, a Saharan paleoriver flowed continuously until isotope Stage 134 (3.35 Ma). When river discharge ceased, wind transport of pollen grains prevailed over fluvial transport. Pollen indicators of trade winds gradually increased between 3.3 and 2.5 Ma. A strong aridification of the climate of northwestern Africa occurred during isotope Stage 130 (3.26 Ma). Afterwards, humid conditions reestablised followed by another aridification around 2.7 Ma. Repetitive latitudinal shifts of vegetation zones ranging from wooded savanna to desert flora dominated for the first time between between 2.6 and 2.4 Ma as a response to the glacial stages 104, 100 and 98. Although climatic conditions, recorded in the Pliocene, were not as dry as those of the middle and Late Pleistocene, latitudinal vegetation shifts near the end of the Pliocene resembled those of the interglacial-glacial cycles of the Brunhes chron.

Pleistocene planktonic foraminifera at ODP Site 128-798

ODP Site 798 on the Oki Ridge in the Southern Japan Sea yielded the first continuous and well-preserved record of Pleistocene planktonic foraminifers in the Northwestern Pacific Ocean region. Quantitative analysis of planktonic foraminifers completed for 122 samples from the 200-m-thick Pleistocene section cored at ODP Site 798 provides a proxy record of variations in sea-surface temperature, productivity, and circulation during the past 1.6 m.y. in an area beneath the track of the Tsushima Current. Faunal census data allow recognition of five distinct assemblages: (1) type A assemblages dominated by sinistrally coiling forms of Neogloboquadrina pachyderma representing polar-subpolar surface temperatures, (2) type B assemblages dominated by Globigerina bulloides and thought to represent periods of increased surface productivity and upwelling, (3) type C assemblages marked by significant abundances of dextrally coiling forms of N. pachyderma thought to represent the warm transitional waters of the Tsushima Current, (4) type D assemblages distinguished by relatively high percentages of dextral N. pachyderma and Globorotalia inflata that also represent warmer surface temperatures and increased flow of the Tsushima Current, and (5) type E assemblages marked by relatively large numbers of the delicate species Globigerina quinqueloba and Globigerinita spp., indicative of exceptional preservation conditions and/or episodic high production of these taxa. Early and middle Pleistocene coiling patterns of Neogloboquadrina pachyderma at Site 798 can be correlated with Pleistocene coiling trends and planktonic foraminiferal datums established in the onshore Oga Peninsula sequence of Northern Honshu and open-ocean N. pachyderma coiling dominance shifts in the North Pacific region. A sustained early Pleistocene warm period recognized in both the Oga Peninsula sequence and the Northern Pacific can clearly be recognized at Site 798. In addition, the late Pleistocene planktonic foraminiferal record at Site 798 shows good correlation with glaciation/deglaciation events for the Northern Hemisphere as delineated by oxygen isotopes and represents the first detailed analysis of Pleistocene sea-surface temperature changes in the Northwestern Pacific Ocean region.

Incised Pleistocene valleys in the Western Belgium coastal plain: Age, origins and implications for the evolution of the Southern North Sea Basin

The Belgian coastal plain occupies a key position as it is located at the transition between the Southern North Sea Basin and the Strait of Dover. It is characterized by thick sequences (> 20 m) of Pleistocene terrestrial and littoral sediments. Yet the wider stratigraphical and palaeo-environmental significance of these sediments received little attention. In this paper we draw on the results of a recent sedimentological study based on > 100 drillings that spans the Pleistocene sequence, and present new biostratigraphical (pollen, foraminifera, ostracods) data, all revealing a complex history of deposition. The record includes evidence of the development of incised-valley systems that were initiated in the late Middle and Late Pleistocene. Five phases of fluvial incision can be identified. The majority of the infills are deposited in an estuarine environment that passes into a fluvial environment land inward, except the Weichselian infill which has a predominant fluvial origin. The greatest part of the most seaward located zone of the western coastal plain was free of valley incisions, there, shallow marine sediments built up the record. Local biostratigraphical investigations provide a timeframe. The result is placed in a regional context.

ESR dating of pleistocene mammal teeth and its implications for the biostratigraphy and geological evolution of the coastal plain, Rio Grande do Sul, southern Brazil

The fossiliferous deposits in the coastal plain of the Rio Grande do Sul State, Southern Brazil, have been known since the late XIX century; however, the biostratigraphic and chronostratigraphic context is still poorly understood. The present work describes the results of electron spin resonance (ESR) dating in eleven fossil teeth of three extinct taxa (Toxodon platensis, Stegomastodon waringi and Hippidion principale) collected along Chui Creek and nearshore continental shelf, in an attempt to assess more accurately the ages of the fossils and its deposits. This method is based upon the analysis of paramagnetic defects found in biominerals, produced by ionizing radiation emitted by radioactive elements present in the surrounding sediment and by cosmic rays. Three fossils from Chui Creek, collected from the same stratigraphic horizon, exhibit ages between (42 +/- 3) Ka and (34 +/- 7) Ka, using the Combination Uptake model for radioisotopes uptake, while a incisor of Toxodon platensis collected from a stratigraphic level below is much older. Fossils from the shelf have ages ranging from (7 +/- 1) 10(5) Ka to (18 +/- 3) Ka, indicating the mixing of fossils of different epochs. The origin of the submarine fossiliferous deposits seems to be the result of multiple reworking and redeposition cycles by sea-level changes caused by the glacial-interglacial cycles during the Quaternary. The ages indicate that the fossiliferous outcrops at Chui Creek are much younger than previously thought, and that the fossiliferous deposits from the continental shelf encompass Ensenadan to late Lujanian ages (middle to late Pleistocene). (C) 2009 Elsevier Ltd and INQUA. All rights reserved.

NEW DATA ON THE CHRONOLOGY OF THE VALE DO FORNO SEDIMENTARY SEQUENCE (LOWER TAGUS RIVER TERRACE STAIRCASE) AND ITS RELEVANCE AS FLUVIAL ARCHIVE OF THE MIDDLE PLEISTOCENE IN WESTERN IBERIA

NEW DATA ON THE CHRONOLOGY OF THE VALE DO FORNO SEDIMENTARY SEQUENCE (LOWER TAGUS RIVER TERRACE STAIRCASE) AND ITS RELEVANCE AS FLUVIAL ARCHIVE OF THE MIDDLE PLEISTOCENE IN WESTERN IBERIA Pedro P. Cunha 1, António A. Martins 2, Jan-Pieter Buylaert 3,4, Andrew S. Murray 4, Luis Raposo 5, Paolo Mozzi 6, Martin Stokes 7 1 MARE - Marine and Environmental Sciences Centre, Department of Earth Sciences, University of Coimbra, Portugal: pcunha@dct.uc.pt 2 MARE - Marine and Environmental Sciences Centre, Dep. Geociências, University of Évora, Portugal; aam@uevora.pt 3 Centre for Nuclear Technologies, Technical University of Denmark, Risø Campus, Denmark; jabu@dtu.dk 4 Nordic Laboratory for Luminescence Dating, Aarhus University, Risø DTU, Denmark; anmu@dtu.dk 5 Museu Nacional de Arqueologia, Lisboa, Portugal; 3raposos@sapo.pt 6 Department of Geosciences, University of Padova, Italy; paolo.mozzi@unipd.it 7 School of Geography, Earth and Environmental Sciences, University of Plymouth, UK; m.stokes@plymouth.ac.uk The stratigraphic units that record the evolution of the Tagus River in Portugal (study area between Vila Velha de Ródão and Porto Alto villages; Fig. 1) have different sedimentary characteristics and lithic industries (Cunha et al., 2012): - a culminant sedimentary unit (the ancestral Tagus, before the drainage network entrenchment) – SLD13 (+142 to 262 m above river bed – a.r.b.; with probable age ca. 3,6 to 1,8 Ma), without artefacts; - T1 terrace (+84 to 180 m; ca. 1000? to 900 ka), without artefacts; - T2 terrace (+57 to 150 m; top deposits with a probable age ca. 600 ka), without artefacts; - T3 terrace (+43 to 113 m; ca. 460 to 360? ka), without artefacts; - T4 terrace (+26 to 55 m; ca. 335 a 155 ka), Lower Paleolithic (Acheulian) at basal and middle levels but early Middle Paleolithic at top levels; - T5 terrace (+5 to 34 m; 135 to 73 ka), Middle Paleolithic (Mousterian; Levallois technique); - T6 terrace (+3 to 14 m; 62 to 32 ka), late Middle Paleolithic (late Mousterian); - Carregueira Sands (aeolian sands) and colluvium (+3 a ca. 100 m; 32 to 12 ka), Upper Paleolithic to Epipaleolithic; - alluvial plain (+0 to 8 m; ca. 12 ka to present), Mesolithic and more recent industries. The differences in elevation (a.r.b.) of the several terrace staircases results from differential uplift due to active faults. Longitudinal correlation with the terrace levels indicates that a graded profile ca. 200 km long was achieved during terrace formation periods and a strong control by sea base level was determinant for terrace formation. The Neogene sedimentary units constituted the main source of sediments for the fluvial terraces (Fig. 2). Geomorphological mapping, coupled with lithostratigraphy, sedimentology and luminescence dating (quartz-OSL and K-feldspar post-IRIR290) were used in this study focused on the T4 terrace, which comprises a Lower Gravels (LG) unit and an Upper Sand (US) unit. The thick, coarse and dominantly massive gravels of the LG unit indicate deposition by a coarse bed-load braided river, with strong sediment supply, high gradient and fluvial competence, during conditions of rapidly rising sea level. Luminescence dating only provided minimum ages but it is probable that the LG unit corresponds to the earlier part of the MIS9 (ca. 335 to 325 ka), immediately postdating the incision promoted by the very low sea level (reaching ca. -140 m) during MIS10 (362 to 337 ka), a period of relatively cold climate conditions with weak vegetation cover on slopes and low sea level. Fig. 1. Main Portuguese reaches in which the Tagus River can be divided (Lower Tagus Basin): I – from the Spanish border to Arneiro (a general E–W trend, mainly consisting of polygonal segments); II – from Arneiro to Gavião (NE–SW); III – from Gavião to Arripiado (E–W); IV – from Arripiado to Vila Franca de Xira (NNE-SSW); V – from Vila Franca de Xira to the Atlantic shoreline. The faults considered to be the limit of the referred fluvial sectors are: F1 – Ponsul-Arneiro fault (WSW-ENE); F2 – Gavião fault (NW-SE); F3 – Ortiga fault (NW-SE); F4 – Vila Nova da Barquinha fault (W-E); F5 – Arripiado-Chamusca fault (NNE-SSW). 1 – estuary; 2 – terraces; 3 – faults; 4 – Tagus main channel. The main Iberian drainage basins are also represented (inset). The lower and middle parts of the US unit, comprising an alternation of clayish silts with paleosols and minor sands to the east (flood-plain deposits) and sand deposits to the west (channel belt), have a probable age of ca. 325 to 200 ka. This points to formation during MIS9 to MIS7, under conditions of high to medium sea levels and warm to mild conditions. The upper part of the US unit, dominated by sand facies and with OSL ages of ca. 200 to 154 ka, correlates with the early part of the MIS6. During this period, progradation resulted from climate deterioration and relative depletion of vegetation that promoted enhanced sediment production in the catchment, coupled with initiation of sea-level lowering that increased the longitudinal slope. The Vale do Forno and Vale da Atela archaeological sites (Alpiarça, central Portugal) document the earliest human occupation in the Lower Tagus River, well established in geomorphological and environmental terms, within the Middle Pleistocene. The Lower Palaeolithic sites were found on the T4 terrace (+26 m, a.r.b.). The oldest artefacts previously found in the LG unit, display crude bifacial forms that can be attributed to the Acheulian, with a probable age of ca. 335 to 325 ka. The T4 US unit has archaeological sites stratigraphically documenting successive phases of an evolved Acheulian, that probably date ca. 325 to 300 ka. Notably, these Lower Palaeolithic artisans were able to produce tools with different sophistication levels, simply by applying different strategies: more elaborated reduction sequences in case of bifaces and simple reduction sequences to obtain cleavers. Fig. 2. . Simplified geologic map of the Lower Tagus Cenozoic basin, adapted from the Carta Geológica de Portugal, 1/500000, 1992). The study area (comprising the Vale do Forno and Vale de Atela sites) is located on the more upstream sector of the Lower Tagus River reach IV, between Arripiado and Chamusca villages. 1 – alluvium (Holocene); 2 – terraces (Pleistocene); 3 – sands, silts and gravels (Paleogene to Pliocene); 4 – Sintra Massif (Cretaceous); 5 – limestones, marls, silts and sandstones (Mesozoic); 6 – quartzites (Ordovician); 7 – basement (Proterozoic to Palaeozoic); 8 – main fault. The main Portuguese reaches of the Tagus River are identified (I to V). The VF3 site (Milharós), containing a Final Acheulian industry, with fine and elaborated bifaces) found in a stratigraphic level located between the T4 terrace deposits and a colluvium associated with Late Pleistocene aeolian sands (32 to 12 ka), has an age younger than ca. 154 ka but much older than 32 ka. In the study area, the sedimentary units of the T4 terrace seem to record the river response to sea-level changes and climatically-driven fluctuations in sediment supply. REFERENCES Cunha P. P., Almeida N. A. C., Aubry T., Martins A. A., Murray A. S., Buylaert J.-P., Sohbati R., Raposo L., Rocha L., 2012, Records of human occupation from Pleistocene river terrace and aeolian sediments in the Arneiro depression (Lower Tejo River, central eastern Portugal). Geomorphology, vol. 165-166, pp. 78-90.

Palaeoecology of the Mount Etna bat fauna, coastal Eastern Queensland

Global warming is already threatening many animal and plant communities worldwide, however, the effect of climate change on bat populations is poorly known. Understanding the factors influencing the survival of bats is crucial to their conservation, and this cannot be achieved solely by modern ecological studies. Palaeoecological investigations provide a perspective over a much longer temporal scale, allowing the understanding of the dynamic patterns that shaped the distribution of modern taxa. In this study twelve microchiropteran fossil assemblages from Mount Etna, central-eastern Queensland, ranging in age from more than 500,000 years to the present day, were investigated. The aim was to assess the responses of insectivorous bats to Quaternary environmental changes, including climatic fluctuations and recent anthropogenic impacts. In particular, this investigation focussed on the effects of increasing late Pleistocene aridity, the subsequent retraction of rainforest habitat, and the impact of cave mining following European settlement at Mount Etna. A thorough examination of the dental morphology of all available extant Australian bat taxa was conducted in order to identify the fossil taxa prior to their analysis in term of species richness and composition. This detailed odontological work provided new diagnostic dental characters for eighteen species and one genus. It also provided additional useful dental characters for three species and seven genera. This odontological analysis allowed the identification of fifteen fossil bat taxa from the Mount Etna deposits, all being representatives of extant bats, and included ten taxa identified to the species level (i.e., Macroderma gigas, Hipposideros semoni, Rhinolophus megaphyllus, Miniopterus schreibersii, Miniopterus australis, Scoteanax rueppellii, Chalinolobus gouldii, Chalinolobus dwyeri, Chalinolobus nigrogriseus and Vespadelus troughtoni) and five taxa identified to the generic level (i.e., Mormopterus, Taphozous, Nyctophilus, Scotorepens and Vespadelus). Palaeoecological analysis of the fossil taxa revealed that, unlike the non-volant mammal taxa, bats have remained essentially stable in terms of species diversity and community membership between the mid-Pleistocene rainforest habitat and the mesic habitat that occurs today in the region. The single major exception is Hipposideros semoni, which went locally extinct at Mount Etna. Additionally, while intensive mining operations resulted in the abandonment of at least one cave that served as a maternity roost in the recent past, the diversity of the Mount Etna bat fauna has not declined since European colonisation. The overall resilience through time of the bat species discussed herein is perhaps due to their unique ecological, behavioural, and physiological characteristics as well as their ability to fly, which have allowed them to successfully adapt to their changing environment. This study highlights the importance of palaeoecological analyses as a tool to gain an understanding of how bats have responded to environmental change in the past and provides valuable information for the conservation of threatened modern species, such as H. semoni.

Evolution of the extinct Sabretooths and the American cheetah-like cat

The sabretooths (Smilodon and Homotherium) and the American cheetah-like cat (Miracinonyx) were the top predators in Late Pleistocene America, but became extinct about 13 thousand years ago. As the evolutionary history of these taxa remains poorly understood , we analysed their phylogenetic relationship to extant felids. In contrast to previous molecular studies , our results show that the sabretooths diverge early and are not closely related to any living cats. This supports their morphological placement in a separate subfamily (Machairodontinae). Despite its remarkable morphological similarity to the African cheetah (Acinonyx jubatus), Miracinonyx appears to have evolved from a puma-like ancestor, presumably in response to similar ecological pressures.

Statistical phylogeographic tests of competing 'Lake Carpentaria hypotheses' in the mouth-brooding freshwater fish, Glossamia aprion (Apogonidae)

Glacial cycles during the Pleistocene reduced sea levels and created new land connections in northern Australia, where many currently isolated rivers also became connected via an extensive paleo-lake system, 'Lake Carpentaria'. However, the most recent period during which populations of freshwater species were connected by gene flow across Lake Carpentaria is debated: various 'Lake Carpentaria hypotheses' have been proposed. Here, we used a statistical phylogeographic approach to assess the timing of past population connectivity across the Carpentaria region in the obligate freshwater fish, Glossamia aprion. Results for this species indicate that the most recent period of genetic exchange across the Carpentaria region coincided with the mid- to late Pleistocene, a result shown previously for other freshwater and diadromous species. Based on these findings and published studies for various freshwater, diadromous and marine species, we propose a set of 'Lake Carpentaria' hypotheses to explain past population connectivity in aquatic species: (1) strictly freshwater species had widespread gene flow in the mid- to late Pleistocene before the last glacial maximum; (2) marine species were subdivided into eastern and western populations by land during Pleistocene glacial phases; and (3) past connectivity in diadromous species reflects the relative strength of their marine affinity.

Taxonomy and palaeoecology of Quaternary faunas from caves in eastern tropical Queensland : a record of broad-scale environmental change

Analysis of fossils from cave deposits at Mount Etna (eastern-central Queensland) has established that a species-rich rainforest palaeoenvironment existed in that area during the middle Pleistocene. This unexpected finding has implications for several fields (e.g., biogeography/phylogeography of rainforest-adapted taxa, and the impact of climate change on rainforest communities), but it was unknown whether the Mount Etna sites represented a small refugial patch of rainforest or was more widespread. In this study numerous bone deposits in caves in north-east Queensland are analysed to reconstruct the environmental history of the area during the late Quaternary. Study sites are in the Chillagoe/Mitchell Palmer and Broken River/Christmas Creek areas. The cave fossil records in these study areas are compared with dated (middle Pleistocene-Holocene) cave sites in the Mount Etna area. Substantial taxonomic work on the Mount Etna faunas (particularly dasyurid marsupials and murine rodents) is also presented as a prerequisite for meaningful comparison with the study sites further north. Middle Pleistocene sites at Mount Etna contain species indicative of a rainforest palaeoenvironment. Small mammal assemblages in the Mount Etna rainforest sites (>500-280 ka) are unexpectedly diverse and composed almost entirely of new species. Included in the rainforest assemblages are lineages with no extant representatives in rainforest (e.g., Leggadina), one genus previously known only from New Guinea (Abeomelomys), and forms that appear to bridge gaps between related but morphologically-divergent extant taxa ('B-rat' and 'Pseudomys C'). Curiously, some taxa (e.g., Melomys spp.) are notable for their absence from the Mount Etna rainforest sites. After 280 ka the rainforest faunas are replaced by species adapted to open, dry habitats. At that time the extinct ‘rainforest’ dasyurids and rodents are replaced by species that are either extant or recently extant. By the late Pleistocene all ‘rainforest’ and several ‘dry’ taxa are locally or completely extinct, and the small mammal fauna resembles that found in the area today. The faunal/environmental changes recorded in the Mount Etna sites were interpreted by previous workers as the result of shifts in climate during the Pleistocene. Many samples from caves in the Chillagoe/Mitchell-Palmer and Broken River/Christmas Creek areas are held in the Queensland Museum’s collection. These, supplemented with additional samples collected in the field as well as samples supplied by other workers, were systematically and palaeoecologically analysed for the first time. Palaeoecological interpretation of the faunal assemblages in the sites suggests that they encompass a similar array of palaeoenvironments as the Mount Etna sites. ‘Rainforest’ sites at the Broken River are here interpreted as being of similar age to those at Mount Etna, suggesting the possibility of extensive rainforest coverage in eastern tropical Queensland during part of the Pleistocene. Likewise, faunas suggesting open, dry palaeoenvironments are found at Chillagoe, the Broken River and Mount Etna, and may be of similar age. The 'dry' faunal assemblage at Mount Etna (Elephant hole Cave) dates to 205-170 ka. Dating of one of the Chillagoe sites (QML1067) produced a maximum age for the deposit of approximately 200 ka, and the site is interpreted as being close to that age, supporting the interpretation of roughly contemporaneous deposition at Mount Etna and Chillagoe. Finally, study sites interpreted as being of late Pleistocene-Holocene age show faunal similarities to sites of that age near Mount Etna. This study has several important implications for the biogeography and phylogeography of murine rodents, and represents a major advance in the study of the Australian murine fossil record. Likewise the survey of the northern study areas is the first systematic analysis of multiple sites in those areas, and is thus a major contribution to knowledge of tropical Australian faunas during the Quaternary. This analysis suggests that climatic changes during the Pleistocene affected a large area of eastern tropical Queensland in similar ways. Further fieldwork and dating is required to properly analyse the geographical extent and timing of faunal change in eastern tropical Queensland.

High connectivity in rastrelliger kanagurta: Influence of historical signatures and migratory behaviour inferred from mtDNA Cytochrome b

Phylogeographic patterns and population structure of the pelagic Indian mackerel, Rastrelliger kanagurta were examined in 23 populations collected from the Indonesian-Malaysian Archipelago (IMA) and the West Indian Ocean (WIO). Despite the vast expanse of the IMA and neighbouring seas, no evidence for geographical structure was evident. An indication that R. kanagurta populations across this region are essentially panmictic. This study also revealed that historical isolation was insufficient for R. kanagurta to attain migration drift equilibrium. Two distinct subpopulations were detected between the WIO and the IMA (and adjacent populations); interpopulation genetic variation was high. A plausible explanation for the genetic differentiation observed between the IMA and WIO regions suggest historical isolation as a result of fluctuations in sea levels during the late Pleistocene. This occurrence resulted in the evolution of a phylogeographic break for this species to the north of the Andaman Sea.

Patterns of genetic variation in the endangered European mink (Mustela lutreola L., 1761)

Background: The European mink (Mustela lutreola, L. 1761) is a critically endangered mustelid, which inhabits several main river drainages in Europe. Here, we assess the genetic variation of existing populations of this species, including new sampling sites and additional molecular markers (newly developed microsatellite loci specific to European mink) as compared to previous studies. Probabilistic analyses were used to examine genetic structure within and between existing populations, and to infer phylogeographic processes and past demography. Results: According to both mitochondrial and nuclear microsatellite markers, Northeastern (Russia, Estonia and Belarus) and Southeastern (Romania) European populations showed the highest intraspecific diversity. In contrast, Western European (France and Spain) populations were the least polymorphic, featuring a unique mitochondrial DNA haplotype. The high differentiation values detected between Eastern and Western European populations could be the result of genetic drift in the latter due to population isolation and reduction. Genetic differences among populations were further supported by Bayesian clustering and two main groups were confirmed (Eastern vs. Western Europe) along with two contained subgroups at a more local scale (Northeastern vs. Southeastern Europe; France vs. Spain). Conclusions: Genetic data and performed analyses support a historical scenario of stable European mink populations, not affected by Quaternary climate oscillations in the Late Pleistocene, and posterior expansion events following river connections in both North-and Southeastern European populations. This suggests an eastern refuge during glacial maxima (as already proposed for boreal and continental species). In contrast, Western Europe was colonised more recently following either natural expansions or putative human introductions. Low levels of genetic diversity observed within each studied population suggest recent bottleneck events and stress the urgent need for conservation measures to counteract the demographic decline experienced by the European mink.

滇西北地区晚更新世以来植被演替与气候变化研究

随着全球环境的变化，人们迫切的希望了解整个地球环境的变化过程、规律和未来发展的趋势。对地质历史时期发生过的环境事件的了解，能为我们研究现在的和预测未来的环境变化提供有价值的资料。 孢粉分析作为一种古环境的代用指标，在恢复古植被与古气候方面起着不可替代的作用。而精确的孢粉分析建立在对现代花粉与当地植被的关系正确的认识基础上，由此才可以更准确地提取地层中的花粉所蕴含的植被和环境信息。 云南省地理位置较特殊，地貌复杂，气候类型多样，与之对应的植物种类多样性丰富，植被类型多样。本项研究选择云南省南部和西部地区作为研究地点，采集表土、地表苔藓、蜘蛛网、树皮和树上地衣苔藓五种天然孢粉捕捉器来研究现代花粉与当地植被的关系，为认识现代花粉雨提供新的研究思路。同时，我们在滇西北选择拉市海、文海、哈里谷和属都湖这四个高原湖泊来研究晚更新世以来滇西北地区植被演替和气候变化，为云南历史时期气候变化提供新的研究资料，同时也为全面认识晚更新世以来的气候变化提供新的证据。研究结果如下： 1. 现代花粉雨与当地植被关系的研究 对云南省西北部、中部和南部采集的19个蜘蛛网样品分析得出：云南省西北部样品中共鉴定20个孢粉类型，分属于16个科;云南省中部样品中共鉴定28个类型，分属于23个科;在云南省南部勐腊县采集的样品中共鉴定28个类型，分属于25个科;在望天树北京植物园中采集的样品共鉴定38个类型，分属于34个科;在西双版纳北京植物园中采集的样品中共有11个类型，分属于10个科。结果表明：蜘蛛网样品中分析出的孢粉类型反映了云南省从南到北不同的植被类型，说明蜘蛛网可以作为一种天然孢粉捕捉器来进行现代花粉雨的研究。 同时，在云南西北部文笔水库采集的五种天然孢粉捕捉器（表土、地表苔藓、树皮、蜘蛛网、树上地衣和苔藓）进行了对比研究。结果表明：表土所得的孢粉中木本植物花粉的百分含量为90.5-96%，远大于地表苔藓（53.1-81.7%）、蜘蛛网（61.7%）、树皮（53.8%）和树上地衣、苔藓（50-53.6%）所获得的木本植物花粉的百分含量。与当地植被进行对比结果表明：这五种天然孢粉捕捉器中，表土、地表苔藓和蜘蛛网比树皮和树上地衣、苔藓能更好的反映当地的植被。 2. 滇西北地区晚更新世以来植被演替与气候变化 在过去2, 5000年左右的地质历史时期，滇西北地区植被和气候变化大致经历了以下三个发展阶段。 （1） 2, 5381 B.P—1, 9335 B.P.：属都湖地区（海拔：3620m）主要是以蓼科植物为主的草甸植被，气候寒冷湿润。 （2） 1, 9335 B.P.—1, 2426 B.P.：属都湖地区是以藜科或蒿属为主的草甸植被，气候从湿润过渡到干旱;而在海拔稍低的文海地区（海拔3080m），主要是阔叶栎林或针阔混交林，气候温凉略湿到寒冷干旱。 （3） 1, 2426 B.P.—至今：属都湖地区是以蓼科为主的草甸植被，气候仍寒冷湿润;海拔稍低的哈里谷（海拔3277m）是以松和冷杉为主的针叶林，气候冷干;文海地区的植被逐渐演替为以松和冷杉为主的针阔叶混交林，但栎属花粉的含量远高于哈里谷地区，说明当时文海的气温虽然低，却比哈里谷稍高;而海拔更低的拉市海（海拔2440m）则是以松为主的针叶林，气候比其他几个地区温暖。 在全新世气候最适宜期（约8000 B.P.以来），哈里谷是以栎和松为主的针阔混交林;文海是以松为主的针阔混交林;而拉市海是以松和蕨类植物为主。说明随着海拔的升高（从拉市海到属都湖），温度逐渐下降，植被类型也由暖性针叶林过渡到针阔混交林再到草甸。 从6000 B.P.至今，文海和哈里谷植被在这一阶段都是以松和冷杉为主的暗针叶林，少量混生一些阔叶类植物，气候变得冷湿;属都湖则仍是以蓼科为主的草甸，气候变得更加寒冷。 研究证明：滇西北地区总的气候变化趋势与全球变化规律基本一致，在1,1805—9990 B.P.期间发生新仙女木事件，在8000B.P.以来，气候变得温暖湿润，为全新世气候最适宜期。此后，气候逐渐变得接近现代。