Dataset Information

Assessing the Relationship of Ancient and Modern Populations.

ABSTRACT: Genetic material sequenced from ancient samples is revolutionizing our understanding of the recent evolutionary past. However, ancient DNA is often degraded, resulting in low coverage, error-prone sequencing. Several solutions exist to this problem, ranging from simple approach, such as selecting a read at random for each site, to more complicated approaches involving genotype likelihoods. In this work, we present a novel method for assessing the relationship of an ancient sample with a modern population, while accounting for sequencing error and postmortem damage by analyzing raw reads from multiple ancient individuals simultaneously. We show that, when analyzing SNP data, it is better to sequence more ancient samples to low coverage: two samples sequenced to 0.5× coverage provide better resolution than a single sample sequenced to 2× coverage. We also examined the power to detect whether an ancient sample is directly ancestral to a modern population, finding that, with even a few high coverage individuals, even ancient samples that are very slightly diverged from the modern population can be detected with ease. When we applied our approach to European samples, we found that no ancient samples represent direct ancestors of modern Europeans. We also found that, as shown previously, the most ancient Europeans appear to have had the smallest effective population sizes, indicating a role for agriculture in modern population growth.

SUBMITTER: Schraiber JG

PROVIDER: S-EPMC5753871 | biostudies-other | 2018 Jan

REPOSITORIES: biostudies-other

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Assessing the Relationship of Ancient and Modern Populations.

Schraiber Joshua G JG

Genetics 20171122 1

Genetic material sequenced from ancient samples is revolutionizing our understanding of the recent evolutionary past. However, ancient DNA is often degraded, resulting in low coverage, error-prone sequencing. Several solutions exist to this problem, ranging from simple approach, such as selecting a read at random for each site, to more complicated approaches involving genotype likelihoods. In this work, we present a novel method for assessing the relationship of an ancient sample with a modern p ...[more]

PMID: 29167200

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Project description:BACKGROUND: The extant roe deer (Capreolus Gray, 1821) includes two species: the European roe deer (C. capreolus) and the Siberian roe deer (C. pygargus) that are distinguished by morphological and karyotypical differences. The Siberian roe deer occupies a vast area of Asia and is considerably less studied than the European roe deer. Modern systematics of the Siberian roe deer remain controversial with 4 morphological subspecies. Roe deer fossilized bones are quite abundant in Denisova cave (Altai Mountains, South Siberia), where dozens of both extant and extinct mammalian species from modern Holocene to Middle Pleistocene have been retrieved. METHODOLOGY/PRINCIPAL FINDINGS: We analyzed a 629 bp fragment of the mitochondrial control region from ancient bones of 10 Holocene and four Pleistocene Siberian roe deer from Denisova cave as well as 37 modern specimen belonging to populations from Altai, Tian Shan (Kyrgyzstan), Yakutia, Novosibirsk region and the Russian Far East. Genealogical reconstructions indicated that most Holocene haplotypes were probably ancestral for modern roe deer populations of Western Siberia and Tian Shan. One of the Pleistocene haplotypes was possibly ancestral for modern Yakutian populations, and two extinct Pleistocene haplotypes were close to modern roe deer from Tian Shan and Yakutia. Most modern geographical populations (except for West Siberian Plains) are heterogeneous and there is some tentative evidence for structure. However, we did not find any distinct phylogenetic signal characterizing particular subspecies in either modern or ancient samples. CONCLUSION/SIGNIFICANCE: Analysis of mitochondrial DNA from both ancient and modern samples of Siberian roe deer shed new light on understanding the evolutionary history of roe deer. Our data indicate that during the last 50,000 years multiple replacements of populations of the Siberian roe deer took place in the Altai Mountains correlating with climatic changes. The Siberian roe deer represent a complex and heterogeneous species with high migration rates and without evident subspecies structure. Low genetic diversity of the West Siberian Plain population indicates a recent bottleneck or founder effect.

Dataset Information

Assessing the Relationship of Ancient and Modern Populations.

Publications

Assessing the Relationship of Ancient and Modern Populations.

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