Wang Weiran, Qiao Yu, Pan Wenshi, Yao Meng
School of Life Sciences, Peking University, Beijing, China.
School of Life Sciences, Peking University, Beijing, China; Chongzuo Biodiversity Research Institute of Peking University, Guangxi, China.
PLoS One. 2015 Jun 9;10(6):e0129782. doi: 10.1371/journal.pone.0129782. eCollection 2015.
Many Asian colobine monkey species are suffering from habitat destruction and population size decline. There is a great need to understand their genetic diversity, population structure and demographic history for effective species conservation. The white-headed langur (Trachypithecus leucocephalus) is a Critically Endangered colobine species endemic to the limestone karst forests in southwestern China. We analyzed the mitochondrial DNA (mtDNA) control region sequences of 390 fecal samples from 40 social groups across the main distribution areas, which represented one-third of the total extant population. Only nine haplotypes and 10 polymorphic sites were identified, indicating remarkably low genetic diversity in the species. Using a subset of 77 samples from different individuals, we evaluated genetic variation, population structure, and population demographic history. We found very low values of haplotype diversity (h = 0.570 ± 0.056) and nucleotide diversity (π = 0.00323 ± 0.00044) in the hypervariable region I (HVRI) of the mtDNA control region. Distribution of haplotypes displayed marked geographical pattern, with one population (Chongzuo, CZ) showing a complete lack of genetic diversity (having only one haplotype), whereas the other population (Fusui, FS) having all nine haplotypes. We detected strong population genetic structure among habit patches (ΦST = 0.375, P < 0.001). In addition, the Mantel test showed a significant correlation between the pairwise genetic distances and geographical distances among social groups in FS (correlation coefficient = 0.267, P = 0.003), indicting isolation-by-distance pattern of genetic divergence in the mtDNA sequences. Analyses of demographic history suggested an overall stable historical population size and modest population expansion in the last 2,000 years. Our results indicate different genetic diversity and possibly distinct population history for different local populations, and suggest that CZ and FS should be considered as one evolutionarily significant unit (ESU) and two management units (MUs) pending further investigation using nuclear markers.
许多亚洲叶猴物种正遭受栖息地破坏和种群数量下降的困扰。为了有效地保护物种，非常有必要了解它们的遗传多样性、种群结构和种群历史。白头叶猴（Trachypithecus leucocephalus）是一种极度濒危的叶猴物种，仅分布于中国西南部的石灰岩喀斯特森林中。我们分析了来自主要分布区域40个社群群体的390份粪便样本的线粒体DNA（mtDNA）控制区序列，这些样本占现存种群总数的三分之一。仅鉴定出9个单倍型和10个多态性位点，表明该物种的遗传多样性极低。我们使用来自不同个体的77个样本子集，评估了遗传变异、种群结构和种群历史。我们发现mtDNA控制区高变区I（HVRI）的单倍型多样性（h = 0.570 ± 0.056）和核苷酸多样性（π = 0.00323 ± 0.00044）的值非常低。单倍型分布呈现出明显的地理格局，其中一个种群（崇左，CZ）完全缺乏遗传多样性（只有一个单倍型），而另一个种群（扶绥，FS）拥有所有9个单倍型。我们在栖息地斑块之间检测到强烈的种群遗传结构（ΦST = 0.375，P < 0.001）。此外，Mantel检验显示FS社群群体之间的成对遗传距离与地理距离之间存在显著相关性（相关系数 = 0.267，P = 0.003），表明mtDNA序列的遗传分化存在距离隔离模式。种群历史分析表明，历史种群规模总体稳定，在过去2000年中有适度的种群扩张。我们的结果表明不同的当地种群具有不同的遗传多样性和可能不同的种群历史，并建议在使用核标记进行进一步调查之前，应将CZ和FS视为一个进化显著单元（ESU）和两个管理单元（MU）。
