scholarly journals Ancient genomes redate the extinction of Sussemionus, a subgenus of Equus, to late Holocene

2021 ◽  
Author(s):  
Dawei Cai ◽  
Siqi Zhu ◽  
Mian Gong ◽  
Naifan Zhang ◽  
Jia Wen ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
North America ◽  
Ancient Dna ◽  
Fossil Record ◽  
Late Holocene ◽  
Northern China ◽  
High Quality ◽  
The Last Glacial Maximum ◽  
The Last Glacial

The exceptionally-rich fossil record available for the equid family has provided textbook examples of macroevolutionary changes. Horses, asses and zebras represent three extant subgenus of Equus lineage, while the Sussemionus subgenus is another remarkable Equus lineage ranging from North America to Ethiopia in Pleistocene. We sequenced 26 archaeological specimens from northern China in Holocene showing morphological features reminiscent of Equus ovodovi, a species representative of Sussemionus, and further confirmed them as this species by genetic analyses. Thus, we present the first high-quality complete genome of the Sussemionus that we sequenced to 12.0× depth-of-coverage and demonstrate that it survived until ~3,500 years ago, despite the continued demographic collapse during the Last Glacial Maximum and the great human expansion in East Asia. We also confirmed the Equus tree, and found Sussemionus diverged from the ancestor of non-caballine equids ~2.3-2.7 Million years ago and admixture events could have taken place between them. Our works suggest the small genetic diversity but not the enhanced inbreeding mainly limited the chances of survival of the species, and illustrates how ancient DNA can inform on extinction dynamics and the long-term resilience of species surviving in cryptic population pockets.

Spatial variation of East Asian winter monsoon evolution between northern and southern China since the last glacial maximum

2021 ◽  
pp. 1-14
Author(s):  
Qin Li ◽  
Haibin Wu ◽  
Jun Cheng ◽  
Shuya Zhu ◽  
Chunxia Zhang ◽  
...  
Keyword(s):  
East Asian Winter Monsoon ◽  
Southern China ◽  
Ice Sheets ◽  
Northern China ◽  
Winter Monsoon ◽  
Asian Winter Monsoon ◽  
Spatial Differences ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract The East Asian winter monsoon (EAWM) is one of the most dynamic components of the global climate system. Although poorly understood, knowledge of long-term spatial differences in EAWM variability during the glacial–interglacial cycles is important for understanding the dynamic processes of the EAWM. We reconstructed the spatiotemporal characteristics of the EAWM since the last glacial maximum (LGM) using a comparison of proxy records and long-term transient simulations. A loess grain-size record from northern China (a sensitive EAWM proxy) and the sea surface temperature gradient of an EAWM index in sediments of the southern South China Sea were compared. The data–model comparison indicates pronounced spatial differences in EAWM evolution, with a weakened EAWM since the LGM in northern China but a strengthened EAWM from the LGM to the early Holocene, followed by a weakening trend, in southern China. The model results suggest that variations in the EAWM in northern China were driven mainly by changes in atmospheric carbon dioxide (CO2) concentration and Northern Hemisphere ice sheets, whereas orbital insolation and ice sheets were important drivers in southern China. We propose that the relative importance of insolation, ice sheets, and atmospheric CO2 for EAWM evolution varied spatially within East Asia.

Geographic patterns of genetic diversity in North American trees: a continent-wide analysis

2021 ◽  
Author(s):  
Andrew V. Gougherty
Keyword(s):  
Genetic Diversity ◽  
Population Genetics ◽  
North America ◽  
North American ◽  
Tree Species ◽  
Geographic Patterns ◽  
Study Characteristics ◽  
Dispersal Traits ◽  
The Last Glacial Maximum ◽  
The Last Glacial

In the northern hemisphere, many species have been reported to have greater genetic diversity in southern populations than northern populations - ostensibly due to migration northward following the last glacial maximum (LGM). The generality of this pattern, while well-established for some taxa, remains unclear for North American trees. To address this issue, I collected published population genetics data for 73 North American tree species, and tested whether genetic diversity was associated with latitude or longitude and whether geographic trends were associated with dispersal traits, range or study characteristics. I found there were no general geographic patterns in genetic diversity, and the strength of the geographic gradients were not associated with any species or study characteristics. Species in the northern and western regions of North America tended to have more species with genetic diversity that declined with latitude, but most species had no significant trend. This work shows that North American trees have complex, individualistic, patterns of genetic diversity that may negate explanation by any particular dispersal trait or range characteristic.

scholarly journals Synergy of the westerly winds and monsoons in the lake evolution of global closed basins since the Last Glacial Maximum and implications for hydrological change in central Asia

2020 ◽  
Vol 16 (6) ◽  
pp. 2239-2254
Author(s):  
Yu Li ◽  
Yuxin Zhang
Keyword(s):  
Climate Change ◽  
Northern Hemisphere ◽  
Late Holocene ◽  
Westerly Winds ◽  
Low Latitudes ◽  
Closed Basins ◽  
The Last Glacial Maximum ◽  
The Last Glacial ◽  
Millennial Scale

Abstract. The monsoon system and westerly circulation, to which climate change responds differently, are two important components of global atmospheric circulation interacting with each other in the middle to low latitudes. Relevant research on global millennial-scale climate change in monsoon and westerly regions is mostly devoted to multi-proxy analyses of lakes, stalagmites, ice cores, and marine and eolian sediments. Different responses from these proxies to long-term environmental change make understanding climate change patterns in monsoon and westerly regions difficult. Accordingly, we disaggregated global closed basins into areas governed by monsoon and westerly winds, unified paleoclimate indicators, and added lake models and paleoclimate simulations to emphatically track millennial-scale evolution characteristics and mechanisms of East Asian summer monsoon and westerly winds since the Last Glacial Maximum (LGM). Our results reveal that millennial-scale water balance change exhibits an obvious boundary between global monsoon and westerly regions in closed basins, particularly in the Northern Hemisphere. The effective moisture in most closed basins of the midlatitude Northern Hemisphere mainly exhibits a decreasing trend since the LGM, while that of the low latitudes shows an increasing trend. In the monsoon-dominated closed basins of Asia, a humid climate prevails in the early to mid-Holocene, and a relatively dry climate appears in the LGM and late Holocene. In the westerly-wind-dominated closed basins of Asia, the climate is characterized by a humid LGM and mid-Holocene (MH) compared with the dry early and late Holocene, which is likely to be connected to precipitation brought by the westerly circulation. This study provides insight into the long-term evolution and synergy of westerly winds and monsoon systems as well as a basis for the projection of future hydrological balance.

scholarly journals Genomic evidence of a widespread southern distribution during the Last Glacial Maximum for two eastern North American hickory species

2017 ◽  
Author(s):  
Jordan B. Bemmels ◽  
Christopher W. Dick
Keyword(s):  
Genetic Diversity ◽  
Genetic Structure ◽  
North America ◽  
Last Glacial Maximum ◽  
Temperate Forest ◽  
Eastern North America ◽  
Carya Ovata ◽  
History Of ◽  
The Last Glacial Maximum ◽  
The Last Glacial

AimPhylogeographic studies of temperate forest taxa often infer complex histories involving population subdivision into distinct refugia during the Last Glacial Maximum (LGM). However, temperate forests may have been broadly distributed in southeastern North America during the LGM. We investigate genome-wide genetic structure in two widespread eastern North America tree species to determine if range expansion from a contiguous area or from genetically isolated refugia better explains the postglacial history of trees and forests from this region.LocationEastern North America (ENA).TaxaBitternut hickory (Carya cordiformis (Wangenh.) K.Koch) and shagbark hickory (Carya ovata (Mill.) K.Koch).MethodsGenetic diversity and differentiation indices were calculated from >1,000 nuclear SNP loci genotyped in ca. 180 individuals per species sampled across ENA. Genetic structure was investigated using principle component analysis and genetic clustering algorithms. As an additional tool for inference, areas of suitable habitat during the LGM were predicted using species distribution models (SDMs).ResultsPopulations across all latitudes showed similar levels of genetic diversity. Most genetic variation was weakly differentiated across ENA, with the exception of an outlier population of Carya ovata in Texas. Genetic structure in each species exhibited an isolation-by-distance pattern. SDMs predicted high LGM habitat suitability over much of the southeastern United States.Main conclusionsBoth hickory species likely survived the LGM in a large region of continuous habitat and recolonized northern areas in a single expanding front that encountered few migration barriers. More complex scenarios, such as forest refugia, need not be invoked to explain genetic structure. The genetically distinct Texas population of Carya ovata could represent a separate glacial refugium, but other explanations are possible. Relative to that of other temperate forest regions, the phylogeographic history of ENA may have been exceptionally simple, involving a northward range shift but without well defined refugia.

scholarly journals High unexpected genetic diversity of a narrow endemic terrestrial mollusc

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3069 ◽  
Author(s):  
Pedro M. Madeira ◽  
Rosa M. Chefaoui ◽  
Regina L. Cunha ◽  
Francisco Moreira ◽  
Susana Dias ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Sequence Data ◽  
Land Snails ◽  
Physical Conditions ◽  
Narrow Endemic ◽  
Terrestrial Mollusc ◽  
Central Portugal ◽  
Genetic Survey ◽  
The Last Glacial Maximum ◽  
The Last Glacial

The Iberian Peninsula has an extensive record of species displaying strong genetic structure as a result of their survival in isolated pockets throughout the Pleistocene ice ages. We used mitochondrial and nuclear sequence data to analyze phylogeographic patterns in endemic land snails from a valley of central Portugal (Vale da Couda), putatively assigned toCandidula coudensis, that show an exceptionally narrow distributional range. The genetic survey presented here shows the existence of five main mitochondrial lineages in Vale da Couda that do not cluster together suggesting independent evolutionary histories. Our results also indicate a departure from the expectation that species with restricted distributions have low genetic variability. The putative past and contemporary models of geographic distribution of Vale da Couda lineages are compatible with a scenario of species co-existence in more southern locations during the last glacial maximum (LGM) followed by a post-LGM northern dispersal tracking the species optimal thermal, humidity and soil physical conditions.

scholarly journals Changes in the composition of marine and sea-ice diatoms derived from sedimentary ancient DNA of the eastern Fram Strait over the past 30 000 years

Ocean Science ◽  
2020 ◽  
Vol 16 (5) ◽  
pp. 1017-1032
Author(s):  
Heike H. Zimmermann ◽  
Kathleen R. Stoof-Leichsenring ◽  
Stefan Kruse ◽  
Juliane Müller ◽  
Ruediger Stein ◽  
...  
Keyword(s):  
Sea Ice ◽  
Ancient Dna ◽  
Cold Water ◽  
Taxonomic Composition ◽  
Fram Strait ◽  
Pcr Products ◽  
Ideal Study ◽  
Late Weichselian ◽  
The Last Glacial Maximum ◽  
The Last Glacial

Abstract. The Fram Strait is an area with a relatively low and irregular distribution of diatom microfossils in surface sediments, and thus microfossil records are scarce, rarely exceed the Holocene, and contain sparse information about past richness and taxonomic composition. These attributes make the Fram Strait an ideal study site to test the utility of sedimentary ancient DNA (sedaDNA) metabarcoding. Amplifying a short, partial rbcL marker from samples of sediment core MSM05/5-712-2 resulted in 95.7 % of our sequences being assigned to diatoms across 18 different families, with 38.6 % of them being resolved to species and 25.8 % to genus level. Independent replicates show a high similarity of PCR products, especially in the oldest samples. Diatom sedaDNA richness is highest in the Late Weichselian and lowest in Mid- and Late Holocene samples. Taxonomic composition is dominated by cold-water and sea-ice-associated diatoms and suggests several reorganisations – after the Last Glacial Maximum, after the Younger Dryas, and after the Early and after the Mid-Holocene. Different sequences assigned to, amongst others, Chaetoceros socialis indicate the detectability of intra-specific diversity using sedaDNA. We detect no clear pattern between our diatom sedaDNA record and the previously published IP25 record of this core, although proportions of pennate diatoms increase with higher IP25 concentrations and proportions of Nitzschia cf. frigida exceeding 2 % of the assemblage point towards past sea-ice presence.

Evidence of humans in North America during the Last Glacial Maximum

Science ◽  
2021 ◽  
Vol 373 (6562) ◽  
pp. 1528-1531 ◽  
Author(s):  
Matthew R. Bennett ◽  
David Bustos ◽  
Jeffrey S. Pigati ◽  
Kathleen B. Springer ◽  
Thomas M. Urban ◽  
...  
Keyword(s):  
North America ◽  
Last Glacial Maximum ◽  
Glacial Maximum ◽  
Last Glacial ◽  
The Last Glacial Maximum ◽  
The Last Glacial
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