@article{AlbertiGonzalezPaijmansetal.2018,
  author    = {Alberti, Federica and Gonzalez, Javier and Paijmans, Johanna L. A. and Basler, Nikolas and Preick, Michaela and Henneberger, Kirstin and Trinks, Alexandra and Rabeder, Gernot and Conard, Nicholas J. and Muenzel, Susanne C. and Joger, Ulrich and Fritsch, Guido and Hildebrandt, Thomas and Hofreiter, Michael and Barlow, Axel},
  title     = {Optimized DNA sampling of ancient bones using Computed Tomography scans},
  series = {Molecular ecology resources},
  volume    = {18},
  journal   = {Molecular ecology resources},
  number    = {6},
  publisher = {Wiley},
  address   = {Hoboken},
  issn      = {1755-098X},
  doi       = {10.1111/1755-0998.12911},
  pages     = {1196 -- 1208},
  year      = {2018},
  abstract  = {The prevalence of contaminant microbial DNA in ancient bone samples represents the principal limiting factor for palaeogenomic studies, as it may comprise more than 99\% of DNA molecules obtained. Efforts to exclude or reduce this contaminant fraction have been numerous but also variable in their success. Here, we present a simple but highly effective method to increase the relative proportion of endogenous molecules obtained from ancient bones. Using computed tomography (CT) scanning, we identify the densest region of a bone as optimal for sampling. This approach accurately identifies the densest internal regions of petrous bones, which are known to be a source of high-purity ancient DNA. For ancient long bones, CT scans reveal a high-density outermost layer, which has been routinely removed and discarded prior to DNA extraction. For almost all long bones investigated, we find that targeted sampling of this outermost layer provides an increase in endogenous DNA content over that obtained from softer, trabecular bone. This targeted sampling can produce as much as 50-fold increase in the proportion of endogenous DNA, providing a directly proportional reduction in sequencing costs for shotgun sequencing experiments. The observed increases in endogenous DNA proportion are not associated with any reduction in absolute endogenous molecule recovery. Although sampling the outermost layer can result in higher levels of human contamination, some bones were found to have more contamination associated with the internal bone structures. Our method is highly consistent, reproducible and applicable across a wide range of bone types, ages and species. We predict that this discovery will greatly extend the potential to study ancient populations and species in the genomics era.},
  language  = {en}
}
@misc{BarlowHartmannGonzalezetal.2020,
  author    = {Barlow, Axel and Hartmann, Stefanie and Gonzalez, Javier and Hofreiter, Michael and Paijmans, Johanna L. A.},
  title     = {Consensify},
  series = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  journal   = {Postprints der Universit{\"a}t Potsdam : Mathematisch-Naturwissenschaftliche Reihe},
  number    = {1033},
  issn      = {1866-8372},
  doi       = {10.25932/publishup-47252},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-472521},
  pages     = {24},
  year      = {2020},
  abstract  = {A standard practise in palaeogenome analysis is the conversion of mapped short read data into pseudohaploid sequences, frequently by selecting a single high-quality nucleotide at random from the stack of mapped reads. This controls for biases due to differential sequencing coverage, but it does not control for differential rates and types of sequencing error, which are frequently large and variable in datasets obtained from ancient samples. These errors have the potential to distort phylogenetic and population clustering analyses, and to mislead tests of admixture using D statistics. We introduce Consensify, a method for generating pseudohaploid sequences, which controls for biases resulting from differential sequencing coverage while greatly reducing error rates. The error correction is derived directly from the data itself, without the requirement for additional genomic resources or simplifying assumptions such as contemporaneous sampling. For phylogenetic and population clustering analysis, we find that Consensify is less affected by artefacts than methods based on single read sampling. For D statistics, Consensify is more resistant to false positives and appears to be less affected by biases resulting from different laboratory protocols than other frequently used methods. Although Consensify is developed with palaeogenomic data in mind, it is applicable for any low to medium coverage short read datasets. We predict that Consensify will be a useful tool for future studies of palaeogenomes.},
  language  = {en}
}
@article{BarlowHartmannGonzalezetal.2020,
  author    = {Barlow, Axel and Hartmann, Stefanie and Gonzalez, Javier and Hofreiter, Michael and Paijmans, Johanna L. A.},
  title     = {Consensify},
  series = {Genes / Molecular Diversity Preservation International},
  volume    = {11},
  journal   = {Genes / Molecular Diversity Preservation International},
  number    = {1},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4425},
  doi       = {10.3390/genes11010050},
  pages     = {22},
  year      = {2020},
  abstract  = {A standard practise in palaeogenome analysis is the conversion of mapped short read data into pseudohaploid sequences, frequently by selecting a single high-quality nucleotide at random from the stack of mapped reads. This controls for biases due to differential sequencing coverage, but it does not control for differential rates and types of sequencing error, which are frequently large and variable in datasets obtained from ancient samples. These errors have the potential to distort phylogenetic and population clustering analyses, and to mislead tests of admixture using D statistics. We introduce Consensify, a method for generating pseudohaploid sequences, which controls for biases resulting from differential sequencing coverage while greatly reducing error rates. The error correction is derived directly from the data itself, without the requirement for additional genomic resources or simplifying assumptions such as contemporaneous sampling. For phylogenetic and population clustering analysis, we find that Consensify is less affected by artefacts than methods based on single read sampling. For D statistics, Consensify is more resistant to false positives and appears to be less affected by biases resulting from different laboratory protocols than other frequently used methods. Although Consensify is developed with palaeogenomic data in mind, it is applicable for any low to medium coverage short read datasets. We predict that Consensify will be a useful tool for future studies of palaeogenomes.},
  language  = {en}
}
@article{GonzalezFortesKolbeFernandesetal.2016,
  author    = {Gonz{\´a}lez-Fortes, Gloria M. and Kolbe, Ben and Fernandes, Daniel and Meleg, Ioana N. and Garcia-Vazquez, Ana and Pinto-Llona, Ana C. and Constantin, Silviu and de Torres, Trino J. and Ortiz, Jose E. and Frischauf, Christine and Rabeder, Gernot and Hofreiter, Michael and Barlow, Axel},
  title     = {Ancient DNA reveals differences in behaviour and sociality between brown bears and extinct cave bears},
  series = {Molecular ecology},
  volume    = {25},
  journal   = {Molecular ecology},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0962-1083},
  doi       = {10.1111/mec.13800},
  pages     = {4907 -- 4918},
  year      = {2016},
  abstract  = {Ancient DNA studies have revolutionized the study of extinct species and populations, providing insights on phylogeny, phylogeography, admixture and demographic history. However, inferences on behaviour and sociality have been far less frequent. Here, we investigate the complete mitochondrial genomes of extinct Late Pleistocene cave bears and middle Holocene brown bears that each inhabited multiple geographically proximate caves in northern Spain. In cave bears, we find that, although most caves were occupied simultaneously, each cave almost exclusively contains a unique lineage of closely related haplotypes. This remarkable pattern suggests extreme fidelity to their birth site in cave bears, best described as homing behaviour, and that cave bears formed stable maternal social groups at least for hibernation. In contrast, brown bears do not show any strong association of mitochondrial lineage and cave, suggesting that these two closely related species differed in aspects of their behaviour and sociality. This difference is likely to have contributed to cave bear extinction, which occurred at a time in which competition for caves between bears and humans was likely intense and the ability to rapidly colonize new hibernation sites would have been crucial for the survival of a species so dependent on caves for hibernation as cave bears. Our study demonstrates the potential of ancient DNA to uncover patterns of behaviour and sociality in ancient species and populations, even those that went extinct many tens of thousands of years ago.},
  language  = {en}
}
@article{HofreiterPaijmansGoodchildetal.2015,
  author    = {Hofreiter, Michael and Paijmans, Johanna L. A. and Goodchild, Helen and Speller, Camilla F. and Barlow, Axel and Gonz{\´a}lez-Fortes, Gloria M. and Thomas, Jessica A. and Ludwig, Arne and Collins, Matthew J.},
  title     = {The future of ancient DNA: Technical advances and conceptual shifts},
  series = {Bioessays : ideas that push the boundaries},
  volume    = {37},
  journal   = {Bioessays : ideas that push the boundaries},
  number    = {3},
  publisher = {Wiley-Blackwell},
  address   = {Hoboken},
  issn      = {0265-9247},
  doi       = {10.1002/bies.201400160},
  pages     = {284 -- 293},
  year      = {2015},
  abstract  = {Technological innovations such as next generation sequencing and DNA hybridisation enrichment have resulted in multi-fold increases in both the quantity of ancient DNA sequence data and the time depth for DNA retrieval. To date, over 30 ancient genomes have been sequenced, moving from 0.7x coverage (mammoth) in 2008 to more than 50x coverage (Neanderthal) in 2014. Studies of rapid evolutionary changes, such as the evolution and spread of pathogens and the genetic responses of hosts, or the genetics of domestication and climatic adaptation, are developing swiftly and the importance of palaeogenomics for investigating evolutionary processes during the last million years is likely to increase considerably. However, these new datasets require new methods of data processing and analysis, as well as conceptual changes in interpreting the results. In this review we highlight important areas of future technical and conceptual progress and discuss research topics in the rapidly growing field of palaeogenomics.},
  language  = {en}
}
@misc{TaronLellBarlowetal.2018,
  author    = {Taron, Ulrike H. and Lell, Moritz and Barlow, Axel and Paijmans, Johanna L. A.},
  title     = {Testing of Alignment Parameters for Ancient Samples},
  series = {Genes},
  journal   = {Genes},
  url       = {http://nbn-resolving.de/urn:nbn:de:kobv:517-opus4-409683},
  pages     = {12},
  year      = {2018},
  abstract  = {High-throughput sequence data retrieved from ancient or other degraded samples has led to unprecedented insights into the evolutionary history of many species, but the analysis of such sequences also poses specific computational challenges. The most commonly used approach involves mapping sequence reads to a reference genome. However, this process becomes increasingly challenging with an elevated genetic distance between target and reference or with the presence of contaminant sequences with high sequence similarity to the target species. The evaluation and testing of mapping efficiency and stringency are thus paramount for the reliable identification and analysis of ancient sequences. In this paper, we present 'TAPAS', (Testing of Alignment Parameters for Ancient Samples), a computational tool that enables the systematic testing of mapping tools for ancient data by simulating sequence data reflecting the properties of an ancient dataset and performing test runs using the mapping software and parameter settings of interest. We showcase TAPAS by using it to assess and improve mapping strategy for a degraded sample from a banded linsang (Prionodon linsang), for which no closely related reference is currently available. This enables a 1.8-fold increase of the number of mapped reads without sacrificing mapping specificity. The increase of mapped reads effectively reduces the need for additional sequencing, thus making more economical use of time, resources, and sample material.},
  language  = {en}
}
@article{TaronLellBarlowetal.2018,
  author    = {Taron, Ulrike H. and Lell, Moritz and Barlow, Axel and Paijmans, Johanna L. A.},
  title     = {Testing of Alignment Parameters for Ancient Samples},
  series = {Genes},
  volume    = {9},
  journal   = {Genes},
  number    = {3},
  publisher = {Molecular Diversity Preservation International},
  address   = {Basel},
  issn      = {2073-4425},
  doi       = {10.3390/genes9030157},
  pages     = {1 -- 12},
  year      = {2018},
  abstract  = {High-throughput sequence data retrieved from ancient or other degraded samples has led to unprecedented insights into the evolutionary history of many species, but the analysis of such sequences also poses specific computational challenges. The most commonly used approach involves mapping sequence reads to a reference genome. However, this process becomes increasingly challenging with an elevated genetic distance between target and reference or with the presence of contaminant sequences with high sequence similarity to the target species. The evaluation and testing of mapping efficiency and stringency are thus paramount for the reliable identification and analysis of ancient sequences. In this paper, we present 'TAPAS', (Testing of Alignment Parameters for Ancient Samples), a computational tool that enables the systematic testing of mapping tools for ancient data by simulating sequence data reflecting the properties of an ancient dataset and performing test runs using the mapping software and parameter settings of interest. We showcase TAPAS by using it to assess and improve mapping strategy for a degraded sample from a banded linsang (Prionodon linsang), for which no closely related reference is currently available. This enables a 1.8-fold increase of the number of mapped reads without sacrificing mapping specificity. The increase of mapped reads effectively reduces the need for additional sequencing, thus making more economical use of time, resources, and sample material.},
  language  = {en}
}
@article{TaronLellBarlowetal.2018,
  author    = {Taron, Ulrike H. and Lell, Moritz and Barlow, Axel and Paijmans, Johanna L. A.},
  title     = {Testing of Alignment Parameters for Ancient Samples},
  series = {Genese},
  volume    = {9},
  journal   = {Genese},
  number    = {3},
  publisher = {MDPI},
  address   = {Basel},
  issn      = {2073-4425},
  doi       = {10.3390/genes9030157},
  pages     = {12},
  year      = {2018},
  abstract  = {High-throughput sequence data retrieved from ancient or other degraded samples has led to unprecedented insights into the evolutionary history of many species, but the analysis of such sequences also poses specific computational challenges. The most commonly used approach involves mapping sequence reads to a reference genome. However, this process becomes increasingly challenging with an elevated genetic distance between target and reference or with the presence of contaminant sequences with high sequence similarity to the target species. The evaluation and testing of mapping efficiency and stringency are thus paramount for the reliable identification and analysis of ancient sequences. In this paper, we present 'TAPAS', (Testing of Alignment Parameters for Ancient Samples), a computational tool that enables the systematic testing of mapping tools for ancient data by simulating sequence data reflecting the properties of an ancient dataset and performing test runs using the mapping software and parameter settings of interest. We showcase TAPAS by using it to assess and improve mapping strategy for a degraded sample from a banded linsang (Prionodon linsang), for which no closely related reference is currently available. This enables a 1.8-fold increase of the number of mapped reads without sacrificing mapping specificity. The increase of mapped reads effectively reduces the need for additional sequencing, thus making more economical use of time, resources, and sample material.},
  language  = {en}
}
@article{YuanShengPreicketal.2020,
  author    = {Yuan, Junxia and Sheng, Guilian and Preick, Michaela and Sun, Boyang and Hou, Xindong and Chen, Shungang and Taron, Ulrike Helene and Barlow, Axel and Wang, Linying and Hu, Jiaming and Deng, Tao and Lai, Xulong and Hofreiter, Michael},
  title     = {Mitochondrial genomes of Late Pleistocene caballine horses from China belong to a separate clade},
  series = {Quaternary science reviews : the international multidisciplinary research and review journal},
  volume    = {250},
  journal   = {Quaternary science reviews : the international multidisciplinary research and review journal},
  publisher = {Elsevier},
  address   = {Amsterdam [u.a.]},
  issn      = {0277-3791},
  doi       = {10.1016/j.quascirev.2020.106691},
  pages     = {8},
  year      = {2020},
  abstract  = {There were several species of Equus in northern China during the Late Pleistocene, including Equus przewalskii and Equus dalianensis. A number of morphological studies have been carried out on E. przewalskii and E. dalianensis, but their evolutionary history is still unresolved. In this study, we retrieved near-complete mitochondrial genomes from E. dalianensis and E. przewalskii specimens excavated from Late Pleistocene strata in northeastern China. Phylogenetic analyses revealed that caballoid horses were divided into two subclades: the New World and the Old World caballine horse subclades. The Old World caballine horses comprise of two deep phylogenetic lineages, with modern and ancient Equus caballus and modern E. przewalskii forming lineage I, and the individuals in this study together with one Yakut specimen forming lineage II. Our results indicate that Chinese Late Pleistocene caballoid horses showed a closer relationship to other Eurasian caballine horses than that to Pleistocene horses from North America. In addition, phylogenetic analyses suggested a close relationship between E. dalianensis and the Chinese fossil E. przewalskii, in agreement with previous researches based on morphological analyses. Interestingly, E. dalianensis and the fossil E. przewalskii were intermixed rather than split into distinct lineages, suggesting either that gene flow existed between these two species or that morphology-based species assignment of palaeontological specimens is not always correct. Moreover, Bayesian analysis showed that the divergence time between the New World and the Old World caballoid horses was at 1.02 Ma (95\% CI: 0.86-1.24 Ma), and the two Old World lineages (I \& II) split at 0.88 Ma (95\% CI: 0.69-1.13 Ma), which indicates that caballoid horses seem to have evolved into different populations in the Old World soon after they migrated from North America via the Bering Land Bridge. Finally, the TMRCA of E. dalianensis was estimated at 0.20 Ma (95\% CI: 0.15-0.28 Ma), and it showed a relative low genetic diversity compared with other Equus species.},
  language  = {en}
}