Department of Biology, Section for Computational and RNA Biology, University of Copenhagen, Copenhagen, Denmark.
Institute of Molecular Biology, University of Oregon, Eugene, OR, USA.
Nat Ecol Evol. 2018 Mar;2(3):491-498. doi: 10.1038/s41559-017-0453-7. Epub 2018 Jan 22.
The plains zebra (Equus quagga) is an ecologically important species of the African savannah. It is also one of the most numerous and widely distributed ungulates, and six subspecies have been described based on morphological variation. However, the within-species evolutionary processes have been difficult to resolve due to its high mobility and a lack of consensus regarding the population structure. We obtained genome-wide DNA polymorphism data from more than 167,000 loci for 59 plains zebras from across the species range, encompassing all recognized extant subspecies, as well as three mountain zebras (Equus zebra) and three Grevy's zebras (Equus grevyi). Surprisingly, the population genetic structure does not mirror the morphology-based subspecies delineation, underlining the dangers of basing management units exclusively on morphological variation. We use demographic modelling to provide insights into the past phylogeography of the species. The results identify a southern African location as the most likely source region from which all extant populations expanded around 370,000 years ago. We show evidence for inclusion of the extinct and phenotypically divergent quagga (Equus quagga quagga) in the plains zebra variation and reveal that it was less divergent from the other subspecies than the northernmost (Ugandan) extant population.
平原斑马（Equus quagga）是非洲热带稀树草原生态系统中非常重要的物种。它也是数量最多、分布最广的有蹄类动物之一，根据形态变异已经描述了六个亚种。然而，由于其高迁移性以及对种群结构缺乏共识，种内进化过程一直难以解决。我们从 59 匹平原斑马的超过 167000 个基因座获得了全基因组 DNA 多态性数据，这些斑马来自该物种的整个分布范围，包括所有已识别的现存亚种，以及三只山斑马（Equus zebra）和三只细纹斑马（Equus grevyi）。令人惊讶的是，种群遗传结构与基于形态的亚种划分并不一致，这突显了仅基于形态变异来划分管理单位的危险。我们使用人口统计学模型来深入了解该物种过去的系统地理学。结果确定了南部非洲的一个位置是最有可能的起源地，所有现存的种群大约在 37 万年前从那里扩展而来。我们提供了证据证明已经灭绝且表型差异较大的斑驴（Equus quagga quagga）包含在平原斑马的变异中，并且表明它与其他亚种的差异比最北部（乌干达）的现存种群的差异要小。
