看着美国草原上吃草的野牛群，人们很容易忽视这样一个事实：该物种曾一度被逼到灭绝的边缘。由于商业捕杀和人类施加的其他压力，生活在北门坎的庞大野牛群曾锐减至仅剩数十头。于是问题随之而来：伴随着种群数量的下降，美洲野牛的遗传多样性是否也随之消失了。
A herd of bison grazing on an American prairie can make it easy to overlook the fact that the species was once brought to the brink of extinction. As a result of commercial hunting and other pressures exerted by humans, the huge herds of bison living in North America were reduced to just a few members. The question then arises whether, along with the population drop, the genetic diversity of American bison was lost as well.A 2026 study published in Science offers a qualified answer.
2026年发表在《科学》杂志上的一项研究给出了一个有保留的答案。包括加州大学圣克鲁兹分校科学家在内的研究人员，分析了跨度约为2万年的115个古代和45个现代野牛基因组，以及52个此前已发表的现代基因组。研究结果表明，种群崩溃对野牛群之间联系的破坏，比对其整体遗传多样性的削弱更为严重。加州大学圣克鲁兹分校对该研究的说明解释称，这些基因组数据可以帮助保护主义者做出更明智的决策，以管理孤立的种群。
Researchers, including scientists at the University of California, Santa Cruz, analyzed 115 ancient and 45 modern bison genomes spanning roughly 20,000 years, plus 52 previously published modern genomes. The findings suggest that the collapse disrupted connections between herds more severely than it reduced overall genetic diversity. The UC Santa Cruz account of the research explains that the genomic data could help conservationists make more informed decisions about managing isolated populations.
古代DNA对现代牛群的揭示研究发现，历史上野牛群在北美大陆内陆之间的基因联系，比今天要更加紧密。现代野牛群由于种群数量下降以及将幸存动物限制在不同群体的管理实践，变得更加孤立。这种碎片化至关重要，因为有限的基因流动会增加近亲繁殖的风险，即便该物种整体上仍保留着大量的遗传多样性。换句话说，当各个野牛群彼此日益孤立时，遗传多样性仍可在整个物种中持续存在。
What ancient DNA reveals about modern herdsThe research found that historical bison populations were more genetically connected across the continent’s interior than they are today. Modern herds have become more isolated through population declines and management practices that confined surviving animals to separate groups. This fragmentation matters because limited gene flow can increase inbreeding risks, even when the species retains substantial genetic diversity overall. In other words, genetic diversity can persist across the species while individual herds become increasingly isolated from one another.
研究团队还检验了关于现代野牛普遍存在牛类血统的说法。20世纪初的牧场实验曾将这两种动物杂交，但这种血统的程度一直是个令人担忧的问题。研究人员以古代野牛为基准，在他们检查的97只现代动物中，有32只发现了牛类血统的证据。在检测到该血统的地方，它通常占基因组的2%以下，并可追溯到大约20代前的杂交。被检查的古代动物中没有一只显示出牛类血统。
The team also tested claims that cattle ancestry is widespread among modern bison. Early 20th-century ranching experiments crossed the two species, but the extent of that ancestry has remained a concern. Using ancient bison as a baseline, the researchers found evidence of cattle ancestry in 32 of the 97 modern animals they examined. Where detected, it generally accounted for less than 2% of the genome and was traced to crossbreeding about 20 generations ago. None of the ancient animals examined showed cattle ancestry.
森林野牛这一北方亚种有着不同的基因混合历史。20世纪20年代，加拿大将大约7000头平原野牛迁至伍德布法罗国家公园。研究发现，所有现代森林野牛群都带有一定的平原野牛血统，比例从7%到64%不等。尽管存在这种混合，这两个亚种在遗传上仍然保持不同，这一发现支持对它们进行分开管理。
Wood bison, the northern subspecies, have a different history of genetic mixing. In the 1920s, Canada relocated roughly 7,000 plains bison to Wood Buffalo National Park. The study found that all modern wood bison herds carry some plains bison ancestry, with proportions ranging from 7% to 64%. Despite this mixing, the two subspecies remained genetically distinct, a finding that supports managing them separately.
为了调查过去的联系，研究人员研究了来自怀俄明州五个考古遗址的野牛，其中包括可追溯到约1万500年前的标本，以及过去700年来自大角盆地的11只动物。这些对比揭示了怀俄明州野牛与大陆内陆其他种群之间持续的遗传关系。研究还发现，一些现代野牛群的近亲繁殖率有所上升，其中包括卡克罗克峡谷州立公园野牛群和两个森林野牛群。
To investigate past connections, the researchers studied bison from five archaeological sites in Wyoming, including specimens dating back about 10,500 years, as well as 11 animals from the Bighorn Basin from the past 700 years. The comparisons revealed the ongoing genetic relationships between the bison of Wyoming and other populations from the interior part of the continent. The study also found elevated inbreeding in some modern herds, including the Caprock Canyons State Park herd and two wood bison herds.
连接特定的种群可能有助于恢复基因流动。古代骨骼保留了母系遗传联系2024年发表在《考古科学杂志：报告》上的另一篇论文研究了加拿大艾伯塔省西南部联合国教科文组织世界遗产“击头野牛跳崖处”的野牛骨骼。几千年来，原住民通过将野牛驱赶下悬崖在该遗址猎杀野牛。
Connecting targeted populations could help restore gene flow. Ancient bones hold a maternal genetic linkAnother paper published in 2024 in the Journal of Archaeological Science: Reports studied the bones of bison from Head-Smashed-In Buffalo Jump, a UNESCO World Heritage Site in southwestern Alberta, Canada. Indigenous people hunted bison at the site for thousands of years by driving them off the cliff.
研究人员雷克塞尔·阿西斯、斯凯勒·恩戈、马维斯·陈、肖恩·布贝尔和特蕾萨·M·伯格从21块长骨中提取了DNA，并从17块中获得了可用结果。大多数可追溯到大约6200年至6600年前。在这项研究中，研究团队检查了遵循母系遗传的线粒体DNA，并在古代野牛中识别出了5种变体。
Researchers Rexelle Asis, Skyler Ngo, Mavis Chan, Shawn Bubel, and Theresa M. Burg extracted DNA from 21 long bones and obtained usable results from 17. Most dated to approximately 6,200 to 6,600 years ago. In the study, the team examined mitochondrial DNA, which follows maternal inheritance, and identified five variants among the ancient bison.
在由240头现代野牛组成的对比组中，有4种变体并不存在，而有一种变体与现今的动物共有。古代样本在该遗传标记上也表现出略高的多样性。作者将这些结果解释为19世纪种群瓶颈伴随着某些母系世系丧失的证据。
Four variants were absent from a comparison group of 240 modern bison, while one was shared with present-day animals. The ancient samples also showed slightly greater variety in this genetic marker. The authors interpreted the results as evidence that the 19th-century population bottleneck was accompanied by the loss of some maternal lineages.
该研究具有局限性。线粒体DNA仅代表基因组的一部分，且古代样本量较小。因此，该研究无法确定整个物种有多少整体遗传多样性消失了。这种共有的遗传变体表明，数千年前生活的野牛与今天生活的野牛之间存在延续性。更广泛的研究结果也可能帮助保护主义者评估现代野牛群的孤立程度。
The study has limits. Mitochondrial DNA represents only one part of the genome, and the ancient sample was small. The study therefore cannot establish how much overall genetic diversity disappeared across the species. The shared genetic variant suggests continuity between bison that lived thousands of years ago and those living today. The broader findings may also help conservationists assess how isolated modern bison herds are.