Recent palaeogenetic studies indicate a highly dynamic history in collared lemmings (Dicrostonyx spp.), with several demographical changes linked to climatic fluctuations that took place during the last glaciation. At the western range margin of D. torquatus, these changes were characterized by a series of local extinctions and recolonizations. However, it is unclear whether this pattern represents a local phenomenon, possibly driven by ecological edge effects, or a global phenomenon that took place across large geographical scales. To address this, we explored the palaeogenetic history of the collared lemming using a next‐generation sequencing approach for pooled mitochondrial DNA amplicons. Sequences were obtained from over 300 fossil remains sampled across Eurasia and two sites in North America. We identified five mitochondrial lineages of D. torquatus that succeeded each other through time across Europe and western Russia, indicating a history of repeated population extinctions and recolonizations, most likely from eastern Russia, during the last 50 000 years. The observation of repeated extinctions across such a vast geographical range indicates large‐scale changes in the steppe‐tundra environment in western Eurasia during the last glaciation. All Holocene samples, from across the species' entire range, belonged to only one of the five mitochondrial lineages. Thus, extant D. torquatus populations only harbour a small fraction of the total genetic diversity that existed across different stages of the Late Pleistocene. In North American samples, haplotypes belonging to both D. groenlandicus and D. richardsoni were recovered from a Late Pleistocene site in south‐western Canada. This suggests that D. groenlandicus had a more southern and D. richardsoni a more northern glacial distribution than previously thought. This study provides significant insights into the population dynamics of a small mammal at a large geographical scale and reveals a rather complex demographical history, which could have had bottom‐up effects in the Late Pleistocene steppe‐tundra ecosystem.
Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-pro t purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. China, and is then applied to an undated stalagmite from southern Poland. 46The new method will not replace high-precision U-Th measurements, 47 because the precision of the technique is difficult to quantify. However, it 48 provides a means for dating certain stalagmites undateable by 49 conventional U-Th methods and for refining coarse U-Th chronologies. 50 51
21Climate changes that occurred during the Late Pleistocene have profound effects on the distribution of 22 many plant and animal species and influenced the formation of contemporary faunas and floras of 23 Europe. The course and mechanisms of responses of species to the past climate changes are now 24 being intensively studied by the use of direct radiocarbon dating and genetic analyses of fossil 25 remains. Here, we review the advances in understanding these processes by the example of four 26 mammal species: woolly mammoth (Mammuthus primigenius), cave bear (Ursus spelaeus s. l.), saiga 27 antelope (Saiga tatarica) and collared lemmings (Dicrostonyx ssp.). The cases discussed here as well 28 as others show that the migrations, range shifts and local extinctions were the main responses to 29 climate changes and that the dynamics of these climate driven processes were much more profound 30 2 than it was previously thought. Each species reacted by its individual manner, which depended on its 31 biology and adaptation abilities to the changing environment and climate conditions. The most severe 32 changes in European ecosystems that affected the largest number of species took place around 33-33 31 ka BP, during the Last Glacial Maximum 22-19 ka BP and the Late Glacial warming 15-13 ka BP. 34 35 37 38 84 2008; Palkopoulou et al., 2013). The divergence of lineages I and II was previously estimated to ca. 1 85 Ma ago (Debruyne et al., 2008; Gilbert and Drautz, 2008), however, most recent estimations suggest 86 much younger date about 300 ka BP (Palkopoulou et al., 2013). Coalescent simulations suggested 87 that actual split of three mammoth populations took place around 200 ka BP and was followed by a 88 demographic expansion that started around 121 ka BP (Palkopoulou et al., 2013). This expansion 89 coincides broadly with the end of Eemian Interstadial, which suggests that mammoths survived this 90 4 warm period confined to refugial areas and expanded as climate got cooler at the beginning of 91 Weichselian glaciation (Palkopoulou et al., 2013). Surprisingly, this was not supported by the analyses 92 of the whole paleogenomes, which indicated a much earlier expansion ca. 280 ka years ago and the 93 maximum effective population size during Eemian (Palkopoulou et al., 2015).94 95 96 Fig. 1. Woolly mammoth (Mammuthus primigenius). A -Bayesian phylogeny of Holarctic woolly 97 mammoths based on mtDNA cytochrome b sequences. The tree is a chronogram where branch 98 lengths denote time elapsed since divergence and the position of tips corresponds to calibrated 99 radiocarbon age of samples; B -distribution of paleontological sites with woolly mammoth 100 remains radiocarbon-dated to the indicated periods. Colours indicate mitochondrial DNA lineages 101 (modified after Palkopoulou et al., 2013). 103Despite, the ambiguities in the early history of mammoth populations, ancient DNA revealed also two 104 more recent population turnovers. In the Eemian Interglacial and Early Weichselian, woolly mammoths 105 that belonged to clad...
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