Scientists
decode the genome of a 700,000 year old horse, breaking the record for
oldest genome sequenced and increasing our understanding of horse
evolution.
The prehistoric equine DNA came from a 15 cm (6
inch) long leg bone, partly preserved by the freezing temperatures of
the Yukon Territory, Western Canada, where it was found. Though the bone
was degraded and host to several other organisms like
bacteria, advanced techniques and computer software enabled the team to
extract, prepare and sequence the ancient horse DNA in unprecedented
detail.
The genome was compared with the genomes of other
members of the horse family, including zebras, donkeys and wild Asian
horses. These results revealed that the ancestor of the Equus genus (the
genus all living horses belong to) branched off from other lineages
4-4.5 million years ago.
The DNA samples also revealed that a
Mongolian equine, Przewalski’s horse, is the last living breed of wild
horse. This endangered species is an offshoot of the domestic horse
lineage and diverged about 50,000 years ago. The team were also able to
tell that horse population size fluctuated with the climate and that
olfaction and a strong immune system have continually been selected for.
What does this mean for reading the genomes of other extinct
animals? Though the limit's been pushed back, time elapsed is still a
very important factor. The conditions the remains were buried in are
also critical - permafrost preserves DNA far better than tropical
conditions do. In addition, DNA previously thought too small or decayed
to be usable could still be sequenced. If we're lucky, the genomes of
our ancestors may not be as out of reach as we thought.
Photo: Przewalski’s horse (Equus ferus przewalskii). Credit to Michael Nichols, National Geographic.
http://www.nature.com/news/
http://www.wired.com/
http://
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Scientists
decode the genome of a 700,000 year old horse, breaking the record for
oldest genome sequenced and increasing our understanding of horse
evolution.
The prehistoric equine DNA came from a 15 cm (6 inch) long leg bone, partly preserved by the freezing temperatures of the Yukon Territory, Western Canada, where it was found. Though the bone was degraded and host to several other organisms like bacteria, advanced techniques and computer software enabled the team to extract, prepare and sequence the ancient horse DNA in unprecedented detail.
The genome was compared with the genomes of other members of the horse family, including zebras, donkeys and wild Asian horses. These results revealed that the ancestor of the Equus genus (the genus all living horses belong to) branched off from other lineages 4-4.5 million years ago.
The DNA samples also revealed that a Mongolian equine, Przewalski’s horse, is the last living breed of wild horse. This endangered species is an offshoot of the domestic horse lineage and diverged about 50,000 years ago. The team were also able to tell that horse population size fluctuated with the climate and that olfaction and a strong immune system have continually been selected for.
What does this mean for reading the genomes of other extinct animals? Though the limit's been pushed back, time elapsed is still a very important factor. The conditions the remains were buried in are also critical - permafrost preserves DNA far better than tropical conditions do. In addition, DNA previously thought too small or decayed to be usable could still be sequenced. If we're lucky, the genomes of our ancestors may not be as out of reach as we thought.
Photo: Przewalski’s horse (Equus ferus przewalskii). Credit to Michael Nichols, National Geographic.
http://www.nature.com/news/
http://www.wired.com/
http://
http://
The prehistoric equine DNA came from a 15 cm (6 inch) long leg bone, partly preserved by the freezing temperatures of the Yukon Territory, Western Canada, where it was found. Though the bone was degraded and host to several other organisms like bacteria, advanced techniques and computer software enabled the team to extract, prepare and sequence the ancient horse DNA in unprecedented detail.
The genome was compared with the genomes of other members of the horse family, including zebras, donkeys and wild Asian horses. These results revealed that the ancestor of the Equus genus (the genus all living horses belong to) branched off from other lineages 4-4.5 million years ago.
The DNA samples also revealed that a Mongolian equine, Przewalski’s horse, is the last living breed of wild horse. This endangered species is an offshoot of the domestic horse lineage and diverged about 50,000 years ago. The team were also able to tell that horse population size fluctuated with the climate and that olfaction and a strong immune system have continually been selected for.
What does this mean for reading the genomes of other extinct animals? Though the limit's been pushed back, time elapsed is still a very important factor. The conditions the remains were buried in are also critical - permafrost preserves DNA far better than tropical conditions do. In addition, DNA previously thought too small or decayed to be usable could still be sequenced. If we're lucky, the genomes of our ancestors may not be as out of reach as we thought.
Photo: Przewalski’s horse (Equus ferus przewalskii). Credit to Michael Nichols, National Geographic.
http://www.nature.com/news/
http://www.wired.com/
http://
http://
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