A genome-wide data assessment of the African lion (Panthera leo) population genetic structure and diversity in Tanzania

The African lion (Panthera leo), listed as a vulnerable species on the IUCN Red List of Threatened Species (Appendix II of CITES), is mainly impacted by indiscriminate killing and prey base depletion. Additionally, habitat loss by land degradation and conversion has led to the isolation of some subpopulations, potentially decreasing gene flow and increasing inbreeding depression risks. Genetic drift resulting from weakened connectivity between strongholds can affect the genetic health of the species. In the present study, we investigated the evolutionary history of the species at different spatiotemporal scales. Therefore, the mitochondrial cytochrome b gene (N = 128), 11 microsatellites (N = 103) and 9,103 SNPs (N = 66) were investigated in the present study, including a large sampling from Tanzania, which hosts the largest lion population among all African lion range countries. Our results add support that the species is structured into two lineages at the continental scale (West-Central vs East-Southern), underlining the importance of reviewing the taxonomic status of the African lion. Moreover, SNPs led to the identification of three lion clusters in Tanzania, whose geographical distributions are in the northern, southern and western regions. Furthermore, Tanzanian lion populations were shown to display good levels of genetic diversity with limited signs of inbreeding. However, their population sizes seem to have gradually decreased in recent decades. The highlighted Tanzanian African lion population genetic differentiation appears to have resulted from the combined effects of anthropogenic pressure and environmental/climatic factors, as further discussed.

非洲狮（Panthera leo）被列入《濒危野生动植物种国际贸易公约》（CITES）附录Ⅱ，同时收录于国际自然保护联盟（IUCN）濒危物种红色名录的易危等级，其生存主要受到滥杀滥捕及猎物基础枯竭的威胁。此外，土地退化与土地利用转换导致的栖息地丧失，致使部分亚种群发生隔离，进而可能降低种群间的基因交流水平，增加近交衰退的风险。核心种群间连通性减弱引发的遗传漂变，同样会影响该物种的遗传健康。本研究从不同时空尺度探究了非洲狮的演化历史。据此，本研究针对线粒体细胞色素b基因（mitochondrial cytochrome b gene，样本量N=128）、11个微卫星位点（microsatellites，样本量N=103）以及9103个单核苷酸多态性位点（Single Nucleotide Polymorphism, SNPs，样本量N=66）展开分析，采样涵盖了所有非洲狮分布国中拥有最大狮群规模的坦桑尼亚。本研究结果进一步佐证，非洲狮在大陆尺度下可划分为两个演化支系（中西非支系与东非-南非支系），这凸显了重新审视非洲狮分类学地位的必要性。此外，基于SNPs位点的分析在坦桑尼亚境内鉴定出三个狮子种群集群，其地理分布分别覆盖该国北部、南部与西部地区。进一步分析表明，坦桑尼亚的狮子种群具备较高水平的遗传多样性，仅存在轻微的近交迹象。但近数十年来，该种群的规模呈现逐步下降态势。本研究表明，坦桑尼亚非洲狮种群的遗传分化，系人为活动压力与环境/气候因子共同作用的结果，相关内容将在后续章节中展开进一步探讨。