Abstract
BackgroundThe derivation of domestic cattle from the extinct wild aurochs (Bos primigenius) has been well-documented by archaeological and genetic studies. Genetic studies point towards the Neolithic Near East as the centre of origin for Bos taurus, with some lines of evidence suggesting possible, albeit rare, genetic contributions from locally domesticated wild aurochsen across Eurasia. Inferences from these investigations have been based largely on the analysis of partial mitochondrial DNA sequences generated from modern animals, with limited sequence data from ancient aurochsen samples. Recent developments in DNA sequencing technologies, however, are affording new opportunities for the examination of genetic material retrieved from extinct species, providing new insight into their evolutionary history. Here we present DNA sequence analysis of the first complete mitochondrial genome (16,338 base pairs) from an archaeologically-verified and exceptionally-well preserved aurochs bone sample.MethodologyDNA extracts were generated from an aurochs humerus bone sample recovered from a cave site located in Derbyshire, England and radiocarbon-dated to 6,738±68 calibrated years before present. These extracts were prepared for both Sanger and next generation DNA sequencing technologies (Illumina Genome Analyzer). In total, 289.9 megabases (22.48%) of the post-filtered DNA sequences generated using the Illumina Genome Analyzer from this sample mapped with confidence to the bovine genome. A consensus B. primigenius mitochondrial genome sequence was constructed and was analysed alongside all available complete bovine mitochondrial genome sequences.ConclusionsFor all nucleotide positions where both Sanger and Illumina Genome Analyzer sequencing methods gave high-confidence calls, no discrepancies were observed. Sequence analysis reveals evidence of heteroplasmy in this sample and places this mitochondrial genome sequence securely within a previously identified aurochsen haplogroup (haplogroup P), thus providing novel insights into pre-domestic patterns of variation. The high proportion of authentic, endogenous aurochs DNA preserved in this sample bodes well for future efforts to determine the complete genome sequence of a wild ancestor of domestic cattle.
Highlights
The now-extinct aurochs (Bos primigenius), which ranged throughout much of Eurasia and Northern Africa during the late Pleistocene and early Holocene, is widely accepted as the wild ancestor of modern cattle [1,2]
Sequence analysis reveals evidence of heteroplasmy in this sample and places this mitochondrial genome sequence securely within a previously identified aurochsen haplogroup, providing novel insights into pre-domestic patterns of variation
This is confirmed by genetic analyses of matrilineal mitochondrial DNA sequences, which reveal a marked differentiation between modern B. taurus and B. indicus haplotypes, demonstrating their derivation from two geographically- and genetically-divergent wild populations [5]
Summary
The now-extinct aurochs (Bos primigenius), which ranged throughout much of Eurasia and Northern Africa during the late Pleistocene and early Holocene, is widely accepted as the wild ancestor of modern cattle [1,2]. Archaeological evidence shows that domestication of this formidable animal occurred independently in the Near East and the Indian subcontinent between 10,000–8,000 years ago, giving rise to the two major domestic taxa observed today — humpless Bos taurus (taurine) and humped Bos indicus (zebu), respectively [3,4] This is confirmed by genetic analyses of matrilineal mitochondrial DNA (mtDNA) sequences, which reveal a marked differentiation between modern B. taurus and B. indicus haplotypes, demonstrating their derivation from two geographically- and genetically-divergent wild populations [5]. Genetic studies point towards the Neolithic Near East as the centre of origin for Bos taurus, with some lines of evidence suggesting possible, albeit rare, genetic contributions from locally domesticated wild aurochsen across Eurasia Inferences from these investigations have been based largely on the analysis of partial mitochondrial DNA sequences generated from modern animals, with limited sequence data from ancient aurochsen samples. We present DNA sequence analysis of the first complete mitochondrial genome (16,338 base pairs) from an archaeologically-verified and exceptionally-well preserved aurochs bone sample
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