一個低覆蓋率的基因組序列草圖已從在加拿大育空地區(qū)一處永久凍土地點挖掘出的一件馬骨獲得，時間在距今大約560,000 至780,000年前,。這是迄今所確定的最早的基因組序列,。研究人員將這些數(shù)據(jù)與一匹“晚更新世”馬的基因組序列草圖、五個現(xiàn)代家馬品種的基因組序列草圖,、一匹Przewalski馬和一頭驢的基因組序列草圖進行了對比,。比較基因組研究結(jié)果表明，產(chǎn)生了所有現(xiàn)代馬,、斑馬和驢子的Equus（馬屬動物）分支起源于距今大約400萬-450萬年前,，這比以前所猜測的早得多。該數(shù)據(jù)支持這樣一個觀點：Przewalski馬（蒙古草原一種瀕危的本地亞種）代表著最后幸存下來的野生馬種群,。（生物谷Bioon.com）
生物谷推薦英文摘要：
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.
