State Key Laboratory of Genetic Resources and Evolution, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming, 650223, Yunnan, China.
Kunming College of Life Science, University of Chinese Academy of Sciences, Kunming, 650223, China.
BMC Evol Biol. 2018 Nov 1;18(1):159. doi: 10.1186/s12862-018-1280-4.
Past climatological events and contemporary geophysical barriers shape the distribution, population genetic structure, and evolutionary history of many organisms. The Himalayan region, frequently referred to as the third pole of the Earth, has experienced large-scale climatic oscillations in the past and bears unique geographic, topographic, and climatic areas. The influences of the Pleistocene climatic fluctuations and present-day geographical barriers such as rivers in shaping the demographic history and population genetic structure of organisms in the Nepal Himalaya have not yet been documented. Hence, we examined the effects of late-Quaternary glacial-interglacial cycles and riverine barriers on the genetic composition of Hanuman langurs (Semnopithecus entellus), a colobine primate with a wide range of altitudinal distribution across the Nepalese Himalaya, using the mitochondrial DNA control region (CR, 1090 bp) and cytochrome B (CYTB, 1140 bp) sequences combined with paleodistribution modeling.
DNA sequences were successfully retrieved from 67 non-invasively collected fecal samples belonging to 18 wild Hanuman langur troops covering the entire distribution range of the species in Nepal. We identified 37 haplotypes from the concatenated CR + CYTB (2230 bp) sequences, with haplotype and nucleotide diversities of 0.958 ± 0.015 and 0.0237 ± 0.0008, respectively. The troops were clustered into six major clades corresponding to their river-isolated spatial distribution, with the significantly high genetic variation among these clades confirming the barrier effects of the snow-fed Himalayan rivers on genetic structuring. Analysis of demographic history projected a decrease in population size with the onset of the last glacial maximum (LGM); and, in accordance with the molecular analyses, paleodistribution modeling revealed a range shift in its suitable habitat downward/southward during the LGM. The complex genetic structure among the populations of central Nepal, and the stable optimal habitat through the last interglacial period to the present suggest that the central mid-hills of Nepal served as glacial refugia for the Hanuman langur.
Hanuman langurs of the Nepal Himalaya region exhibit high genetic diversity, with their population genetic structure is strongly shaped by riverine barrier effects beyond isolation by distance; hence, this species demands detailed future phylogenetic study.
过去的气候事件和当代的地球物理屏障塑造了许多生物的分布、种群遗传结构和进化历史。喜马拉雅地区常被称为地球的第三极，过去经历了大规模的气候振荡，拥有独特的地理、地形和气候区域。更新世气候波动和现代地理屏障（如河流）对尼泊尔喜马拉雅地区生物的种群历史和遗传结构的影响尚未有文献记载。因此，我们利用线粒体 DNA 控制区（CR，1090bp）和细胞色素 B（CYTB，1140bp）序列结合古分布模型，研究了晚第四纪冰期-间冰期循环和河流屏障对广泛分布于尼泊尔喜马拉雅山脉的长尾叶猴（Semnopithecus entellus）遗传组成的影响。
从 67 份属于尼泊尔境内 18 个野生长尾叶猴群的非侵入性采集粪便样本中成功获得了 DNA 序列，这些样本覆盖了该物种的整个分布范围。我们从串联的 CR+CYTB（2230bp）序列中鉴定出 37 个单倍型，单倍型和核苷酸多样性分别为 0.958±0.015 和 0.0237±0.0008。这些猴群根据其被河流隔离的空间分布聚类为六个主要分支，这些分支之间存在显著的高遗传变异，证实了喜马拉雅冰雪河流对遗传结构的屏障作用。种群历史分析预测，随着末次冰盛期（LGM）的开始，种群数量减少；并且，与分子分析一致，古分布模型显示，在 LGM 期间，其适宜栖息地向下方/南方转移。尼泊尔中部地区种群之间复杂的遗传结构，以及从中冰期到现在稳定的最佳栖息地，表明尼泊尔中部丘陵地区是长尾叶猴的冰川避难所。
尼泊尔喜马拉雅地区的长尾叶猴表现出高度的遗传多样性，其种群遗传结构受到河流屏障效应的强烈影响，而不仅仅是距离隔离；因此，该物种需要进行详细的未来系统发育研究。
