一个低覆盖率的基因组序列草图已从在加拿大育空地区一处永久冻土地点挖掘出的一件马骨获得，时间在距今大约560,000 至780,000年前。这是迄今所确定的最早的基因组序列。研究人员将这些数据与一匹“晚更新世”马的基因组序列草图、五个现代家马品种的基因组序列草图、一匹Przewalski马和一头驴的基因组序列草图进行了对比。比较基因组研究结果表明，产生了所有现代马、斑马和驴子的Equus（马属动物）分支起源于距今大约400万-450万年前，这比以前所猜测的早得多。该数据支持这样一个观点：Przewalski马（蒙古草原一种濒危的本地亚种）代表着最后幸存下来的野生马种群。（生物谷Bioon.com）
生物谷推荐英文摘要：
Nature doi:10.1038/nature12323
Recalibrating Equus evolution using the genome sequence of an early Middle Pleistocene horse
Ludovic Orlando,Aurélien Ginolhac,Guojie Zhang,Duane Froese, Anders Albrechtsen, Mathias Stiller,Mikkel Schubert,Enrico Cappellini,Bent Petersen,Ida Moltke, Philip L. F. Johnson, Matteo Fumagalli,Julia T. Vilstrup, Maanasa Raghavan,Thorfinn Korneliussen, Anna-Sapfo Malaspinas,Josef Vogt, Damian Szklarczyk, Christian D. Kelstrup,Jakob Vinther,Andrei Dolocan, Jesper Stenderup,Amhed M. V. Velazquez,James Cahill,Morten Rasmussen et al.
The rich fossil record of equids has made them a model for evolutionary processes. Here we present a 1.12-times coverage draft genome from a horse bone recovered from permafrost dated to approximately 560–780 thousand years before present (kyr BP). Our data represent the oldest full genome sequence determined so far by almost an order of magnitude. For comparison, we sequenced the genome of a Late Pleistocene horse (43kyr BP), and modern genomes of five domestic horse breeds (Equus ferus caballus), a Przewalski’s horse (E. f. przewalskii) and a donkey (E(Myr BP), twice the conventionally accepted time to the most recent common ancestor of the genus Equus. We also find that horse population size fluctuated multiple times over the past 2Myr, particularly during periods of severe climatic changes. We estimate that the Przewalski’s and domestic horse populations diverged 38–72kyr BP, and find no evidence of recent admixture between the domestic horse breeds and the Przewalski’s horse investigated. This supports the contention that Przewalski’s horses represent the last surviving wild horse population6. We find similar levels of genetic variation among Przewalski’s and domestic populations, indicating that the former are genetically viable and worthy of conservation efforts. We also find evidence for continuous selection on the immune system and olfaction throughout horse evolution. Finally, we identify 29 genomic regions among horse breeds that deviate from neutrality and show low levels of genetic variation compared to the Przewalski’s horse. Such regions could correspond to loci selected early during domestication.
