Key Laboratory of Animal Ecology and Conservation Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing, China.
PLoS One. 2013 Apr 17;8(4):e61659. doi: 10.1371/journal.pone.0061659. Print 2013.
To understand the evolutionary processes leading to the diversity of Asian colobines, we report here on a phylogenetic, phylogeographical and population genetic analysis of three closely related langurs, Trachypithecus francoisi, T. poliocephalus and T. leucocephalus, which are all characterized by different pelage coloration predominantly on the head and shoulders. Therefore, we sequenced a 395 bp long fragment of the mitochondrial control region from 178 T. francoisi, 54 T. leucocephalus and 19 T. poliocephalus individuals, representing all extant populations of these three species. We found 29 haplotypes in T. francoisi, 12 haplotypes in T. leucocephalus and three haplotypes in T. poliocephalus. T. leucocephalus and T. poliocephalus form monophyletic clades, which are both nested within T. francoisi, and diverged from T. francoisi recently, 0.46-0.27 (T. leucocephalus) and 0.50-0.25 million years ago (T. poliocephalus). Thus, T. francoisi appears as a polyphyletic group, while T. leucocephalus and T. poliocephalus are most likely independent descendents of T. francoisi that are both physically separated from T. francoisi populations by rivers, open sea or larger habitat gaps. Since T. francoisi populations show no variability in pelage coloration, pelage coloration in T. leucocephalus and T. poliocephalus is most likely the result of new genetic mutations after the split from T. francoisi and not of the fixation of different characters derived from an ancestral polymorphism. This case study highlights that morphological changes for example in pelage coloration can occur in isolated populations in relatively short time periods and it provides a solid basis for studies in related species. Nevertheless, to fully understand the evolutionary history of these three langur species, nuclear loci should be investigated as well.
为了理解导致亚洲叶猴多样性的进化过程，我们在此报告了对三种密切相关的长尾猴（T. francoisi、T. poliocephalus 和 T. leucocephalus）的系统发育、系统地理学和群体遗传学分析。这三种长尾猴的头部和肩部的皮毛颜色主要不同，因此，我们对这三个物种的所有现存种群的 178 只 T. francoisi、54 只 T. leucocephalus 和 19 只 T. poliocephalus 个体进行了一段长 395bp 的线粒体控制区序列测定。我们在 T. francoisi 中发现了 29 种单倍型，T. leucocephalus 中发现了 12 种单倍型，T. poliocephalus 中发现了 3 种单倍型。T. leucocephalus 和 T. poliocephalus 形成单系群，均嵌套在 T. francoisi 中，最近与 T. francoisi 分化，时间分别为 0.46-0.27（T. leucocephalus）和 0.50-0.25 百万年前（T. poliocephalus）。因此，T. francoisi 似乎是一个多系群，而 T. leucocephalus 和 T. poliocephalus 很可能是 T. francoisi 的独立后裔，它们都与 T. francoisi 种群在物理上被河流、开阔海域或更大的生境间隙隔开。由于 T. francoisi 种群的皮毛颜色没有多样性，因此 T. leucocephalus 和 T. poliocephalus 的皮毛颜色很可能是与 T. francoisi 分离后新遗传突变的结果，而不是来自祖先多态性的不同特征的固定。这个案例研究强调了例如皮毛颜色等形态变化可以在相对较短的时间内在孤立的种群中发生，并为相关物种的研究提供了坚实的基础。然而，要全面了解这三种叶猴的进化历史，还应该研究核基因座。
