Larison Brenda, Kaelin Christopher B, Harrigan Ryan, Henegar Corneliu, Rubenstein Daniel I, Kamath Pauline, Aschenborn Ortwin, Smith Thomas B, Barsh Gregory S
Department of Ecology and Evolutionary Biology, UCLA, Los Angeles, CA, USA.
Center for Tropical Research, Institute of the Environment and Sustainability, UCLA, Los Angeles, CA, USA.
Mol Ecol. 2021 Jan;30(2):379-390. doi: 10.1111/mec.15728. Epub 2020 Dec 2.
One of the most iconic wild equids, the plains zebra occupies a broad region of sub-Saharan Africa and exhibits a wide range of phenotypic diversity in stripe patterns that have been used to classify multiple subspecies. After decades of relative stability, albeit with a loss of at least one recognized subspecies, the total population of plains zebras has undergone an approximate 25% decline since 2002. Individuals with abnormal stripe patterns have been recognized in recent years but the extent to which their appearance is related to demography and/or genetics is unclear. Investigating population genetic health and genetic structure are essential for developing effective strategies for plains zebra conservation. We collected DNA from 140 plains zebra, including seven with abnormal stripe patterns, from nine locations across the range of plains zebra, and analyzed data from restriction site-associated and whole genome sequencing (RAD-seq, WGS) libraries to better understand the relationships between population structure, genetic diversity, inbreeding, and abnormal phenotypes. We found that genetic structure did not coincide with described subspecific variation, but did distinguish geographic regions in which anthropogenic habitat fragmentation is associated with reduced gene flow and increased evidence of inbreeding, especially in certain parts of East Africa. Further, zebras with abnormal striping exhibited increased levels of inbreeding relative to normally striped individuals from the same populations. Our results point to a genetic cause of stripe pattern abnormalities, and dramatic evidence of the consequences of habitat fragmentation.
平原斑马是最具标志性的野生马科动物之一，分布于撒哈拉以南非洲的广大区域，其条纹图案表现出广泛的表型多样性，这些条纹图案曾被用于划分多个亚种。在经历了数十年的相对稳定（尽管至少有一个公认的亚种消失）之后，自2002年以来，平原斑马的总数量已下降了约25%。近年来，人们发现了条纹图案异常的个体，但其外观与种群统计学和/或遗传学的关联程度尚不清楚。调查种群遗传健康状况和遗传结构对于制定有效的平原斑马保护策略至关重要。我们从平原斑马分布范围内的九个地点采集了140只平原斑马的DNA，其中包括七只条纹图案异常的斑马，并分析了限制性位点相关文库和全基因组测序（RAD-seq、WGS）文库的数据，以更好地了解种群结构、遗传多样性、近亲繁殖和异常表型之间的关系。我们发现，遗传结构与所描述的亚种变异并不一致，但确实区分了地理区域，在这些区域，人为造成的栖息地破碎化与基因流动减少以及近亲繁殖证据增加有关，尤其是在东非的某些地区。此外，与来自相同种群的条纹正常的个体相比，条纹异常的斑马近亲繁殖水平更高。我们的研究结果指出了条纹图案异常的遗传原因，以及栖息地破碎化后果的显著证据。
