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1. ‘They came from the ends of the earth’: long-distance exchange of obsidian in the High Arctic during the Early Holocene

   https://doi.org/10.15184/aqy.2019.2  

   Pitulko, Vladimir V. ; Kuzmin, Yaroslav V. ; Glascock, Michael D. ; Pavlova, Elena Yu. ; Grebennikov, Andrei V. ( February 2019 , Antiquity)

   Zhokhov Island in the Siberian High Arctic has yielded evidence for some of the most remote prehistoric human occupation in the world, as well as the oldest-known dog-sled technology. Obsidian artefacts found on Zhokhov have been provenanced using XRF analysis to allow comparison with known sources of obsidian from north-eastern Siberia. The results indicate that the obsidian was sourced from Lake Krasnoe—approximately 1500km distant—and arrived on Zhokhov Island c . 8000 BP. The archaeological data from Zhokhov therefore indicate a super-long-distance Mesolithic exchange network.
2. Sourcing of obsidian artefacts from the Omolon River basin and the neighbouring region (north‐eastern Siberia): Prehistoric procurement from Kamchatkan and Chukotkan sources

   https://doi.org/10.1111/arcm.12675  

   Kuzmin, Y. V. ; Vorobei, I. E. ; Glascock, M. D. ; Grebennikov, A. V. ( April 2021 , Archaeometry)

   Obsidians sources used by prehistoric people in the Omolon River basin and neighbouring areas of north‐eastern Siberia were determined for 112 artefacts from 30 sites by the energy‐dispersive X‐ray fluorescence (ED‐XRF) method. The main suppliers were the primary obsidian sources in both the Chukotka (Lake Krasnoe) and Kamchatka (Itkavayam, Payalpan and KAM‐8) regions, with distances from sources to sites up to about 300–900 km in a straight line. For the first time, the transport of obsidian from Kamchatkan sources has been detected outside of this territory. The mechanism of obsidian transport was most probably by down‐the‐line movement, especially in the case of the Lake Krasnoe source.
3. Phylogenomics, biogeography, and evolution of morphology and ecological niche of the eastern Asian–eastern North American Nyssa (Nyssaceae)

   https://doi.org/10.1111/jse.12599  

   Zhou, Wenbin ; Xiang, Qiu‐Yun ; Wen, Jun ( June 2020 , Journal of Systematics and Evolution)

   Nyssa(Nyssaceae, Cornales) represents a classical example of the well‐known eastern Asian–eastern North American floristic disjunction. The genus consists of three species in eastern Asia, four species in eastern North America, and one species in Central America. Species of the genus are ecologically important trees in eastern North American and eastern Asian forests. The distribution of living species and a rich fossil record of the genus make it an excellent model for understanding the origin and evolution of the eastern Asian–eastern North American floristic disjunction. However, despite the small number of species, relationships within the genus have remained unclear and have not been elucidated using a molecular approach. Here, we integrate data from 48 nuclear genes, fossils, morphology, and ecological niche to resolve species relationships, elucidate its biogeographical history, and investigate the evolution of morphology and ecological niches, aiming at a better understanding of the well‐known EA–ENA floristic disjunction. Results showed that the Central American (CAM)Nyssa talamancanawas sister to the remaining species, which were divided among three, rapidly diversified subclades. Estimated divergence times and biogeographical history suggested thatNyssahad an ancestral range in Eurasia and western North America in the late Paleocene. The rapid diversification occurred in the early Eocene, followedmore »by multiple dispersals between and within the Erasian and North American continents. The genus experienced two major episodes of extinction in the early Oligocene and end of Neogene, respectively. The Central AmericanN. talamancanarepresents a relic lineage of the boreotropical flora in the Paleocene/Eocene boundary that once diversified in western North America. The results supported the importance of both the North Atlantic land bridge and the Bering land bridge (BLB) for the Paleogene dispersals ofNyssaand the Neogene dispersals, respectively, as well as the role of Central America as refugia of the Paleogene flora. The total‐evidence‐based dated phylogeny suggested that the pattern of macroevolution ofNyssacoincided with paleoclimatic changes. We found a number of evolutionary changes in morphology (including wood anatomy and leaf traits) and ecological niches (precipitation and temperature) between the EA–ENA disjunct, supporting the ecological selection driving trait evolutions after geographic isolation. We also demonstrated challenges in phylogenomic studies of lineages with rapid diversification histories. The concatenation of gene data can lead to inference of strongly supported relationships incongruent with the species tree. However, conflicts in gene genealogies did not seem to impose a strong effect on divergence time dating in our case. Furthermore, we demonstrated that rapid diversification events may not be recovered in the divergence time dating analysis using BEAST if critical fossil constraints of the relevant nodes are not available. Our study provides an example of complex bidirectional exchanges of plants between Eurasia and North America in the Paleogene, but “out of Asia” migrations in the Neogene, to explain the present disjunct distribution ofNyssain EA and ENA.

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4. Population genetics and geographic origins of mallards harvested in northwestern Ohio

   https://doi.org/10.1371/journal.pone.0282874  

   Schummer, Michael L. ; Simpson, John ; Shirkey, Brendan ; Kucia, Samuel R. ; Lavretsky, Philip ; Tozer, Douglas C. ( March 2023 , PLOS ONE)

   Chiang, Tzen-Yuh (Ed.)

   The genetic composition of mallards in eastern North America has been changed by release of domestically-raised, game-farm mallards to supplement wild populations for hunting. We sampled 296 hatch-year mallards harvested in northwestern Ohio, October–December 2019. The aim was to determine their genetic ancestry and geographic origin to understand the geographic extent of game-farm mallard introgression into wild populations in more westward regions of North America. We used molecular analysis to detect that 35% of samples were pure wild mallard, 12% were early generation hybrids between wild and game-farm mallards (i.e., F1–F3), and the remaining 53% of samples were assigned as part of a hybrid swarm. Percentage of individuals in our study with some form of hybridization with game-farm mallard (65%) was greater than previously detected farther south in the mid-continent (~4%), but less than the Atlantic coast of North America (~ 92%). Stable isotope analysis using δ 2 H f suggested that pure wild mallards originated from areas farther north and west than hybrid mallards. More specifically, 17% of all Ohio samples had δ 2 H f consistent with more western origins in the prairies, parkland, or boreal regions of the mid-continent of North America, with 55%, 35%, and 10%more »of these being genetically wild, hybrid swarm, and F3, respectively. We conclude that continued game-farm introgression into wild mallards is not isolated to the eastern population of mallards in North America, and may be increasing and more widespread than previously detected. Mallards in our study had greater incidence of game-farm hybridization than other locales in the mid-continent but less than eastern North American regions suggesting further need to understand game-farm mallard genetic variation and movement across the continent.« less
5. A Climatology of Extratropical Cyclones Leading to Extreme Weather Events over Central and Eastern North America

   https://doi.org/10.1175/MWR-D-18-0453.1  

   Bentley, Alicia M. ; Bosart, Lance F. ; Keyser, Daniel ( May 2019 , Monthly Weather Review)

   Cool-season extreme weather events (EWEs) (i.e., high-impact weather events that are societally disruptive, geographically widespread, exceptionally prolonged, and climatologically infrequent) are typically associated with strong extratropical cyclones (ECs). The opportunity to investigate the genesis locations, tracks, and frequencies of ECs leading to EWEs over central and eastern North America and compare them to those of ordinary ECs forming over and traversing the same region motivates this study. ECs leading to EWEs are separated from ordinary ECs according to the magnitude, areal extent, and duration of their 925-hPa standardized wind speed anomalies in the 0.5° NCEP CFSR dataset. This separation allows for the construction of an October–March 1979–2016 climatology of ECs leading to EWEs over central and eastern North America. The climatology of ECs leading to EWEs over central and eastern North America reveals that these ECs typically form in the lee of the Rocky Mountains, over the south-central United States, and along the east coast of North America at latitudes equatorward of the typical genesis locations of ordinary ECs. ECs leading to EWEs exhibit equatorward-shifted tracks relative to ordinary ECs, likely associated with an equatorward shift in the position of the subtropical or polar-front jet. ECs leading to EWEs formmore »most frequently in November and March, when the seasonal alignment of baroclinic and diabatic forcings is maximized. Similar to ordinary ECs, the genesis locations, tracks, and frequencies of ECs leading to EWEs are partially determined by the states of the Pacific–North American pattern and North Atlantic Oscillation.

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