中文摘要：

马属动物丰富的化石材料,记录了其5 500万年的起源、迁徙、灭绝和进化,使其成为进化生物学的教研材料。马属动物于始新世时期出现于北美,称为始马。由于气候的变化,导致白令海峡水面的上升和下降,马属祖先曾陆续经由白令桥抵达欧亚古路,但是均没有留下现存物种后代。马属动物在北美持续演化,到上新世时,现代马属的最近祖先出现,即上新马。在接下来约3百万年间,马属动物经历快速的辐射进化,在不同的环境中占领生态位,形成包括马、驴和斑马3个主要亚属。促成现存马属物种在极短的时间内分离的主要原因,是马属典型的快速核型进化。随着马基因组精细图和驴基因组草图的完成,及分子生物学的研究,马属核型多样性的识别越来越精准。马属动物剧烈的染色体重排,让科学家们越来越相信,其异种杂交能够产生后代,后代没有繁殖能力的原因是马属动物基因组之间的高度相似,使得其杂种能够存活;但是由于核型的巨大差异,其杂种后代生殖细胞在减数分裂时,不能均衡的分配两套染色体,但这个猜测仍需要大量的试验来证实。

英文摘要：

The rich fossil record of Equus over the past 55 million years were punctuated by many episodes of origin,migration,extinction and evolution,which has made them as a textbook example of evolution.The ancestors of Equus originated in Northern America continent in the Eocene period,called Hyracotherium.As the climate changes,the Bering Strait sea level rise and fall.The Equus groups colonized the Old World several times crossing Beringia but they left no descendants there.Equus genus continued to evolve in North America.Until the Pliocene,the most recent common ancestor of present-day Equus emerged,called Pliohippus.Within the following 3million years,their ancestors rapidly expanded and occupied the ecological niches in different geographical areas,radiating into 3main subgenus（horse,donkey and zebra）.The main reason for facilitating the speciation was the acute chromosomal rearrangements.With the publication of the horse whole-genome sequences and the donkey draft genome sequences,and the pro-gress of biomolecule level,the identification of Equus species karyotype diversity is more profound.More and more scientists believe that the mechanism of which Equus interspecies hybridization can produce offspring is based on the high similarity of genome sequence.And their hybrid offspring infertility is caused by the karyotype diversity which makes the meiotic recombination breakdown.This assumption still needs to be confirmed by experiments.