Relatively Recent Evolution of Pelage Coloration in Colobinae: Phylogeny and Phylogeography of Three Closely Related Langur Species

<div><p>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, <i>Trachypithecus francoisi</i>, <i>T. poliocephalus</i> and <i>T. leucocephalus</i>, 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 <i>T. francoisi</i>, 54 <i>T. leucocephalus</i> and 19 <i>T. poliocephalus</i> individuals, representing all extant populations of these three species. We found 29 haplotypes in <i>T. francoisi,</i> 12 haplotypes in <i>T. leucocephalus</i> and three haplotypes in <i>T. poliocephalus</i>. <i>T. leucocephalus</i> and <i>T. poliocephalus</i> form monophyletic clades, which are both nested within <i>T. francoisi</i>, and diverged from <i>T. francoisi</i> recently, 0.46-0.27 (<i>T. leucocephalus</i>) and 0.50-0.25 million years ago (<i>T. poliocephalus</i>). Thus, <i>T. francoisi</i> appears as a polyphyletic group, while <i>T. leucocephalus</i> and <i>T. poliocephalus</i> are most likely independent descendents of <i>T. francoisi</i> that are both physically separated from <i>T. francoisi</i> populations by rivers, open sea or larger habitat gaps. Since <i>T. francoisi</i> populations show no variability in pelage coloration, pelage coloration in <i>T. leucocephalus</i> and <i>T. poliocephalus</i> is most likely the result of new genetic mutations after the split from <i>T. francoisi</i> 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.</p></div

Head and shoulder coloration of François’s langur (<i>Trachypithecus francoisi</i>; left), white-headed langur (<i>T. leucocephalus</i>; middle) and golden-headed langur (<i>T. poliocephalus</i>; right).

<p>Head and shoulder coloration of François’s langur (<i>Trachypithecus francoisi</i>; left), white-headed langur (<i>T. leucocephalus</i>; middle) and golden-headed langur (<i>T. poliocephalus</i>; right).</p

Minimum-spanning network for <i>T. francoisi, T. leucocephalus</i> and <i>T. poliocephalus</i> haplotypes.

<p>Each circle represents a haplotype and the diameter scales to haplotype frequency. Mutational steps are represented by black dots on lines connecting haplotypes. Sampling lots are presented as colored circles.</p

Distribution and sampling sites of <i>T. francoisi</i> (Lots 01–13), <i>T. leucocephalus</i> (Lots 14–16) and <i>T. poliocephalus</i> (Lot 17).

<p>Distribution and sampling sites of <i>T. francoisi</i> (Lots 01–13), <i>T. leucocephalus</i> (Lots 14–16) and <i>T. poliocephalus</i> (Lot 17).</p

Phylogenetic relationships among <i>T. francoisi, T. leucocephalus</i> and <i>T. poliocephalus</i> haplotypes.

<p>Labels refer to haplotype identification numbers (see <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0061659#pone.0061659.s001" target="_blank">Table S1</a>). Values above branches indicate support for each node based on ML/MP/Bayesian algorithms, respectively. Bootstrap values <50% are not shown. Divergence age estimates for major nodes are depicted in circles along with their 95% credibility intervals (grey bars). Sampling lots are presented as colored rectangles.</p

Summary of haplotype diversity (<i>h</i>), nucleotide diversity (<i>π</i>), test of selective neutrality (Tajima’s <i>D</i>, Fu’s <i>F_s</i>, Fu and Li’s <i>D^*</i> and Fu and Li’s <i>F^*</i>) and population parameters of theta (θ) and growth parameter (g) of HVI region sequences of <i>T. francoisi</i>, <i>T. leucocephalus</i> and <i>T. poliocephalus.</i>

<p>Values of SSD, <i>Hri</i> and <i>R₂</i> are also showed.</p

Bayesian skyline plot of past demographic trends and mismatch distributions based on haplotypes of <i>T. francoisi</i> (A and C) and <i>T. leucocephalus</i> (B and D).

<p>In a) and b), x-axis represents time in mya; y-axis represents estimated population size (units = <i>Neτ</i>, the product of effective population size and generation time in years, log-transformed). The mean estimate and the 95% HPD limits are indicated as black and blue lines, respectively. In c) and d), the frequencies of pairwise differences haplotypes are shown.</p