Beringia as an Ice Age genetic museum

2003 ◽  
Vol 60 (1) ◽  
pp. 94-100 ◽  
Author(s):  
Beth Shapiro ◽  
Alan Cooper
Keyword(s):  
Time Scales ◽  
Late Pleistocene ◽  
Ancient Dna ◽  
Human Impacts ◽  
Phylogenetic Analyses ◽  
Genetic Data ◽  
Ice Age ◽  
Ecological Change ◽  
Landscape Mosaics ◽  
New Perspective

AbstractThousands of Late Pleistocene remains are found in sites throughout Beringia. These specimens comprise an Ice Age genetic museum, and the DNA contained within them provide a means to observe evolutionary processes within populations over geologically significant time scales. Phylogenetic analyses can identify the taxonomic positions of extinct species and provide estimates of speciation dates. Geographic and temporal divisions apparent in the genetic data can be related to ecological change, human impacts, and possible landscape mosaics in Beringia. The application of ancient DNA techniques to traditional paleontological studies provides a new perspective to long-standing questions regarding the paleoenvironment and diversity of Late Pleistocene Beringia.

Palaeolithic Cave Art at Creswell Crags in European Context

2007 ◽  
Keyword(s):  
Late Pleistocene ◽  
Rock Art ◽  
Ice Age ◽  
Upper Palaeolithic ◽  
Southern France ◽  
European Context ◽  
The World ◽  
Cave Art ◽  
Illustrated Book

Cave art is a subject of perennial interest among archaeologists. Until recently it was assumed that it was largely restricted to southern France and northern Iberia, although in recent years new discoveries have demonstrated that it originally had a much wider distribution. The discovery in 2003 of the UK's first examples of cave art, in two caves at Creswell Crags on the Derbyshire/Nottinghamshire border, was the most surprising illustration of this. The discoverers (the editors of the book) brought together in 2004 a number of Palaeolithic archaeologists and rock art specialists from across the world to study the Creswell art and debate its significance, and its similarities and contrasts with contemporary Late Pleistocene ("Ice Age") art on the Continent. This comprehensively illustrated book presents the Creswell art itself, the archaeology of the caves and the region, and the wider context of the Upper Palaeolithic era in Britain, as well as a number of up-to-date studies of Palaeolithic cave art in Spain, Portugal, France, and Italy which serve to contextualize the British examples.

Emergence of critical climate states during the Pleistocene

2021 ◽  
Author(s):  
Nicholas Golledge
Keyword(s):  
Dynamical Systems ◽  
Late Pleistocene ◽  
Dominant Frequency ◽  
Climate System ◽  
Ice Age ◽  
Early Pleistocene ◽  
Glacial Cycles ◽  
Pleistocene Climate ◽  
System Nodes ◽  
Systems Framework

<p>During the Pleistocene (approximately 2.6 Ma to present) glacial to interglacial climate variability evolved from dominantly 40 kyr cyclicity (Early Pleistocene) to 100 kyr cyclicity (Late Pleistocene to present). Three aspects of this period remain poorly understood: Why did the dominant frequency of climate oscillation change, given that no major changes in orbital forcing occurred? Why are the longer glacial cycles of the Late Pleistocene characterised by a more asymmetric form with abrupt terminations? And how can the Late Pleistocene climate be controlled by 100 kyr cyclicity when astronomical forcings of this frequency are so much weaker than those operating on shorter periods? Here we show that the decreasing frequency and increasing asymmetry that characterise Late Pleistocene ice age cycles both emerge naturally in dynamical systems in response to increasing system complexity, with collapse events (terminations) occuring only once a critical state has been reached. Using insights from network theory we propose that evolution to a state of criticality involves progressive coupling between climate system 'nodes', which ultimately allows any component of the climate system to trigger a globally synchronous termination. We propose that the climate state is synchronised at the 100 kyr frequency, rather than at shorter periods, because eccentricity-driven insolation variability controls mean temperature change globally, whereas shorter-period astronomical forcings only affect the spatial pattern of thermal forcing and thus do not favour global synchronisation. This dynamical systems framework extends and complements existing theories by accomodating the differing mechanistic interpretations of previous studies without conflict.</p>

Time-scale dependence of climate-carbon cycle feedbacks for weak perturbations in CMIP5 models

2021 ◽  
Author(s):  
Guilherme Torres Mendonça ◽  
Julia Pongratz ◽  
Christian Reick
Keyword(s):  
Climate Change ◽  
Carbon Cycle ◽  
Time Scales ◽  
Radiative Forcing ◽  
Global Carbon Cycle ◽  
Atmospheric Co2 ◽  
Ice Age ◽  
Cmip5 Models ◽  
Global Carbon ◽  
Different Time Scales

<p>The increase in atmospheric CO2 driven by anthropogenic emissions is the main radiative forcing causing climate change. But this increase is not only a result from emissions, but also from changes in the global carbon cycle. These changes arise from feedbacks between climate and the carbon cycle that drive CO2 into or out of the atmosphere in addition to the emissions, thereby either accelerating or buffering climate change. Therefore, understanding the contribution of these feedbacks to the global response of the carbon cycle is crucial in advancing climate research. Currently, this contribution is quantified by the α-β-γ framework (Friedlingstein et al., 2003). But this quantification is only valid for a particular perturbation scenario and time period. In contrast, a recently proposed generalization (Rubino et al., 2016) of this framework for weak perturbations quantifies this contribution for all scenarios and at different time scales. </p><p>Thereby, this generalization provides a systematic framework to investigate the response of the global carbon cycle in terms of the climate-carbon cycle feedbacks. In the present work we employ this framework to study these feedbacks and the airborne fraction in different CMIP5 models. We demonstrate (1) that this generalization of the α-β-γ framework consistently describes the linear dynamics of the carbon cycle in the MPI-ESM; and (2) how by this framework the climate-carbon cycle feedbacks and airborne fraction are quantified at different time scales in CMIP5 models. Our analysis shows that, independently of the perturbation scenario, (1) the net climate-carbon cycle feedback is negative at all time scales; (2) the airborne fraction generally decreases for increasing time scales; and (3) the land biogeochemical feedback dominates the model spread in the airborne fraction at all time scales. This last result therefore emphasizes the need to improve our understanding of this particular feedback.</p><p><strong>References:</strong></p><p>P. Friedlingstein, J.-L. Dufresne, P. Cox, and P. Rayner. How positive is the feedback between climate change and the carbon cycle? Tellus B, 55(2):692–700, 2003.</p><p>M. Rubino, D. Etheridge, C. Trudinger, C. Allison, P. Rayner, I. Enting, R. Mulvaney, L. Steele, R. Langenfelds, W. Sturges, et al. Low atmospheric CO2 levels during the Little Ice Age due to cooling-induced terrestrial uptake. Nature Geoscience, 9(9):691–694, 2016.</p>

scholarly journals Palynological profile and depositional environment of the Ishim formation (upper Miocene) in Tobol-Ishim interfluve, Western Siberia

2019 ◽  
Vol 27 (6) ◽  
pp. 103-123
Author(s):  
O. B. Kuzmina ◽  
I. V. Khazina ◽  
P. V. Smirnov ◽  
A. O. Konstantinov ◽  
A. R. Agatova
Keyword(s):  
Late Pleistocene ◽  
Organic Substance ◽  
Late Miocene ◽  
Depositional Environment ◽  
Western Siberia ◽  
Ice Age ◽  
Quaternary Sediments ◽  
Upper Miocene ◽  
Neogene Sediments ◽  
First Time

For the first time some outcrops of the Upper Miocene Ishim Formation on the south of Tyumen Area near Pyatkovo, Masali and Bigila villages are studied by palynological method in detail. A series of mineralogical analyzes of these sediments and radiocarbon analysis of the Quaternary sediments overlying the Ishim Formation are done. Four palynocomplexes (PC) are established in the Ishim Formation: PC1 with Botryococcus; PC2 with Botryococcus, Sigmopollis; PC3 with Alnus, Polypodiaceae, Botryococcus, Sigmopollis; PC4 with Betula, Alnus, Corylus. The layers with PC1, PC2 и PC3 are traced in two outcrops near Masali and Bigila Villages. PC4 is revealed from the sands and aleuropelits of the outcrop near Pyatkovo Village, it is characterized by a significant content of diverse pollen of temperate termophylic broad-leafed taxa and by the presence of rare typical Miocene elements (Таxodiaceae, Nyssa, Tsuga). The PC3 and PC4 are compared with the complexes well known from the Neogene sediments of Western Siberia. PC5 with Betula, Herbae, Fungi is revealed from the bedded silts overlying the Ishim Formation in Masali outcrop. Previously, these sediments were attributed to the Late Miocene Pavlodar Formation. The composition and the structure of PC5 allowed making an assumption about Quaternary age of the enclosing sediments. Radiocarbon analysis of the organic substance from the silts showed, that these sediments were accumulated in the Late Pleistocene (Sartan Ice Age). For the first time the information about microphytoplankton (Botryococcus, Pediastrum, Zygnemataceae, Sigmopollis) and other nonpollen palynomorphs, contained in Ishim Formation (Upper Miocene) and in Pleistocene sediments, is given. On palynological data, some stages of development of the Late Miocene Ishim Basin and the type of vegetation surrounding this basin are considered. The depositional environment of Pleistocene sediments (Masali outcrop) is reconstructed.

A multiproxy reconstruction of vegetation dynamics in the Eastern Alps (Switzerland): combining paleoecological and paleogenetic approaches.

2021 ◽  
Author(s):  
Laura Dziomber ◽  
Lisa Gurtner ◽  
Maria Leunda ◽  
Christoph Schwörer
Keyword(s):  
Climate Change ◽  
Ancient Dna ◽  
Vegetation Dynamics ◽  
Population Decline ◽  
Future Climate ◽  
Ice Age ◽  
Future Climate Change ◽  
The Holocene ◽  
Plant Remains ◽  
The Impact

<p>Current and future climate change is a serious threat to biodiversity and ecosystem stability. With a rapid increase of global temperatures by 1.5°C since the pre-industrial period and a projected warming of 1.5-4°C by the end of this century, plant species are forced to either adapt to these changes, shift their distribution range to higher elevation, or face population decline and extinction. Today, there is an urgent need to better understand the responses of mountain vegetation to climate change in order to predict the consequences of the human-driven global change currently occurring during the Anthropocene and maintain species diversity and ecosystem services. However, most predictions are based on short-term experiments. There is, in general, an insufficient use of longer time scales in conservation biology to understand long-term processes. Palaeoecological data are a great source of information to infer past species responses to changing environmental factors, such as climate or anthropogenic disturbances.</p><p>The last climate change of a similar magnitude and rate as projected for this century was the transition between the last Ice Age and the Holocene interglacial (ca. 11,700 years ago). By analyzing subfossil plant remains such as plant macrofossils, charcoal and pollen from natural archives, we can study past responses to climate change. However, until recently it was not possible to reconstruct changes at the population level. With the development of new methods to extract ancient DNA (aDNA) from plant remains and next generation DNA-sequencing techniques, we can now infer past population dynamics by analyzing the genetic variation through time. Ancient DNA might also be able to reveal if species could adapt to climatic changes by identifying intraspecific variation of specific genes related to climatic adaptations.</p><p>We are currently investigating a palaeoecological archive from a high-altitude mountain lake, Lai da Vons (1991 m a.s.l), situated in Eastern Switzerland. We are presenting preliminary macrofossil, pollen and charcoal results to reconstruct local to regional vegetation and fire dynamics with high chronological precision and resolution. In a next step, we will use novel molecular methods, in order to track adaptive and neutral genetic diversity through the Holocene by analyzing aDNA from subfossil conifer needles. The overarching goal of this large-scale, multiproxy study is to better understand past vegetation dynamics and the impact of future climate change on plants at multiple scales; from the genetic to the community level.</p><p> </p>

scholarly journals Genetic structure and biogeographic history of the Bicknell’s Thrush/ Gray-cheeked Thrush species complex

The Auk ◽  
2019 ◽  
Vol 137 (1) ◽  
Author(s):  
Alyssa M Fitzgerald ◽  
Jason Weir ◽  
Joel Ralston ◽  
Ian G Warkentin ◽  
Darroch M Whitaker ◽  
...  
Keyword(s):  
Genetic Structure ◽  
Late Pleistocene ◽  
Species Complex ◽  
Extended Period ◽  
Genetic Data ◽  
Distribution Models ◽  
Biogeographic History ◽  
History Of ◽  
Low Levels ◽  
Bicknell's Thrush

Abstract We examined species limits, admixture, and genetic structure among populations in the Bicknell’s Thrush (Catharus bicknelli)–Gray-cheeked Thrush (C. minimus) species complex to establish the geographic and temporal context of speciation in this group, which is a model system in ecology and a high conservation priority. We obtained mitochondrial ND2 sequences from 186 Bicknell’s Thrushes, 77 Gray-cheeked Thrushes, and 55 individuals of their closest relative, the Veery (C. fuscescens), and genotyped a subset of individuals (n = 72) at 5,633 anonymous single nucleotide polymorphic (SNP) loci. Between-species sequence divergence was an order of magnitude greater than divergence within each species, divergence was dated to the late Pleistocene (420 kbp) based on Bayesian coalescence estimation, and a coalescent model (IMa) revealed almost no gene flow between species based on ND2. SNP data were consistent with mitochondrial results and revealed low levels of admixture among species (3 of 37 Bicknell’s Thrushes, no Gray-cheeked Thrushes, and no Veeries were >2% admixed). Species distribution models projected to the Last Glacial Maximum suggest that Bicknell’s Thrush and Gray-cheeked Thrush resided in primarily allopatric refugia in the late Pleistocene, consistent with the genetic data that support reproductive isolation over an extended period of time. Our genetic data suggest that both species underwent demographic expansions, possibly as they expanded out of Pleistocene refugia into their current ranges. We conclude that Bicknell’s Thrush and Gray-cheeked Thrush are 2 distinct species-level lineages despite low levels of Gray-cheeked Thrush introgression in Bicknell’s Thrushes, and divergence has been maintained by a long history of allopatry in subtly different habitats. Their unique phylogeography among boreal forest birds indicates that either cryptic species breaks in eastern North America are still undiscovered, or another factor, such as divergent natural selection, high migratory connectivity, or interspecific competition, played a role in their divergence.

Decadal–Multidecadal Variations of Asian Summer Rainfall from the Little Ice Age to the Present

2019 ◽  
Vol 32 (22) ◽  
pp. 7663-7674 ◽  
Author(s):  
Hui Shi ◽  
Bin Wang ◽  
Jian Liu ◽  
Fei Liu
Keyword(s):  
Time Scales ◽  
Time Scale ◽  
Southern Oscillation ◽  
Summer Rainfall ◽  
Ice Age ◽  
Uniform Structure ◽  
Maritime Continent ◽  
Remarkable Change ◽  
Decadal Time Scale ◽  
Asian Summer

Abstract Features of decadal–multidecadal variations of the Asian summer rainfall are revealed by analysis of the reconstructed Asian summer precipitation (RAP) dataset from 1470 to 2013. Significant low-frequency periodicities of the all-Asian rainfall (AAR) index (AARI) are found on decadal (8–10 yr), quasi-bidecadal (22 yr), and multidecadal (50–54 yr) time scales, as well as centennial time scales. The decadal and multidecadal peaks are mainly from the “monsoon Asia” area and the Maritime Continent, while the 22-yr peak is from the “arid Asia” area. A remarkable change of leading frequency from multidecadal to decadal after AD 1700 is detected across the entire Asian landmass. The leading empirical orthogonal function (EOF) modes on the decadal and multidecadal time scales exhibit a uniform structure similar to that on the interannual time scale, suggesting a cross-time-scale, in-phase variation of the rainfall across continental Asia and the Maritime Continent. Enhanced AAR on a decadal time scale is found associated with the mega-La Niña sea surface temperature (SST) pattern over the Pacific. The AARI–mega-ENSO (El Niño–Southern Oscillation) relationship is persistently significant except from 1820 to around 1900. Enhanced decadal AAR is also found to be associated with extratropical North Atlantic warming. The AARI–AMO (Atlantic multidecadal oscillation) relationship, however, is nonstationary. On the multidecadal time scale, the AAR is significantly related to the AMO. Mechanisms associated with the decadal–multidecadal variability of AAR are also discussed.

scholarly journals Ancient DNA suggests modern wolves trace their origin to a Late Pleistocene expansion from Beringia

2020 ◽  
Vol 29 (9) ◽  
pp. 1596-1610 ◽  
Author(s):  
Liisa Loog ◽  
Olaf Thalmann ◽  
Mikkel‐Holger S. Sinding ◽  
Verena J. Schuenemann ◽  
Angela Perri ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Ancient Dna

scholarly journals Ancient DNA shows high faunal diversity in the Lesser Caucasus during the Late Pleistocene

2019 ◽  
Vol 219 ◽  
pp. 102-111 ◽  
Author(s):  
Mariya Antonosyan ◽  
Frederik V. Seersholm ◽  
Alicia C. Grealy ◽  
Milo Barham ◽  
Daniel Werndly ◽  
...  
Keyword(s):  
Late Pleistocene ◽  
Ancient Dna ◽  
Faunal Diversity ◽  
Lesser Caucasus

Late Pleistocene chronology and the glacial–interglacial cycle

1974 ◽  
Vol 111 (5) ◽  
pp. 421-430
Author(s):  
P. Evans
Keyword(s):  
Time Scales ◽  
Late Pleistocene ◽  
Time Scale ◽  
Deep Sea ◽  
Average Length ◽  
Climatic Cycle ◽  
Radiometric Data

SummaryAlternative time-scales differing by 25% have been proposed for the climatic sequence revealed by deep-sea cores. Both scales are based on radiometric data. Recent evidence which is here summarized favours the time-scale which gives the smaller values for the ages of late Pleistocene events; it supports the estimate of 40 ka rather than 50 ka for the average length of the principal climatic cycle.

Sign in / Sign up

Export Citation Format

Share Document