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Taxonomic Revision and Evolutionary Phylogeography of Dusky Langur (Trachypithecus obscurus) in Peninsular Malaysia.

ABSTRACT: Dusky langur, Trachypithecus obscurus, inhabits tropical rainforests in Peninsular Malaysia, Thailand, and Myanmar. Morphologically, five subspecies are distributed in Peninsular Malaysia, but few studies have used genetic data to verify the classification. It is difficult to differentiate subspecies based on morphological characteristics, so this study used molecular data to differentiate subspecies of T. obscurus. The issue was addressed by analyzing 723 and 649 base pairs of the mitochondrial D-loop region and COI, respectively. DNA amplifications were performed using species-specific primer toward 35 individuals representing different populations. Phylogenetic analyses showed that two main clades representing populations in southern and northern Peninsular Malaysia. The results demonstrate that subspecies of T. obscurus in Peninsular Malaysia does not support classification based on the morphology that recognizes five subspecies. Previous study based on morphology that classified the subspecies on Perhentian Island, Terengganu, as T. obscurus styx is not recognized in this study. This subspecies happened to merge with the population in northern Peninsular Malaysia. Trachypithecus o. styx probably inhabited the southern peninsula and, due to the terminal Pleistocene sea level rise, spread to the east coast but could not spread farther because the subspecies was situated on offshore islands during the period. This assumption was supported by the molecular clock, which showed that subspecies on Perhentian Island spread after the Perlis population (T. obscurus flavicauda).

SUBMITTER: Aifat NR

PROVIDER: S-EPMC8181166 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:BACKGROUND: The dusky dolphin (Lagenorhynchus obscurus) is distributed along temperate, coastal regions of New Zealand, South Africa, Argentina, and Peru where it feeds on schooling anchovy, sardines, and other small fishes and squid tightly associated with temperate ocean sea surface temperatures. Previous studies have suggested that the dusky dolphin dispersed in the Southern Hemisphere eastward from Peru via a linear, temperate dispersal corridor provided by the circumpolar west-wind drift. With new mitochondrial and nuclear DNA sequence data, we propose an alternative phylogeographic history for the dusky dolphin that was structured by paleoceanographic conditions that repeatedly altered the distribution of its temperate prey species during the Plio-Pleistocene. RESULTS: In contrast to the west-wind drift hypothesis, phylogenetic analyses support a Pacific/Indian Ocean origin, with a relatively early and continued isolation of Peru from other regions. Dispersal of the dusky dolphin into the Atlantic is correlated with the history of anchovy populations, including multiple migrations from New Zealand to South Africa. Additionally, the cooling of the Eastern Equatorial Pacific led to the divergence of anchovy populations, which in turn explains the north-south equatorial transgression of L. obliquidens and the subsequent divergence of L. obscurus in the Southern Hemisphere. CONCLUSION: Overall, our study fails to support the west-wind drift hypothesis. Instead, our data indicate that changes in primary productivity and related abundance of prey played a key role in shaping the phylogeography of the dusky dolphin, with periods of ocean change coincident with important events in the history of this temperate dolphin species. Moderate, short-term changes in sea surface temperatures and current systems have a powerful effect on anchovy populations; thus, it is not infeasible that repeated fluctuations in anchovy populations continue to play an important role in the history of coastal dolphin populations.

Project description:BACKGROUND: The evolutionary history of the Asian colobines is less understood. Although monophyly of the odd-nosed monkeys was recently confirmed, the relationships among the langur genera Presbytis, Semnopithecus and Trachypithecus and their position among Asian colobines remained unclear. Moreover, in Trachypithecus various species groups are recognized, but their affiliations are still disputed. To address these issues, mitochondrial and Y chromosomal sequence data were phylogenetically related and combined with presence/absence analyses of retroposon integrations. RESULTS: The analysed 5 kb fragment of the mitochondrial genome allows no resolution of the phylogenetic relationships among langur genera, but five retroposon integrations were detected which link Trachypithecus and Semnopithecus. According to Y chromosomal data and a 573 bp fragment of the mitochondrial cytochrome b gene, a common origin of the species groups T. [cristatus], T. [obscurus] and T. [francoisi] and their reciprocal monophyly is supported, which is also underpinned by an orthologous retroposon insertion. T. [vetulus] clusters within Semnopithecus, which is confirmed by two retroposon integrations. Moreover, this species group is paraphyletic, with T. vetulus forming a clade with the Sri Lankan, and T. johnii with the South Indian form of S. entellus. Incongruence between gene trees was detected for T. [pileatus], in that Y chromosomal data link it with T. [cristatus], T. [obscurus] and T. [francoisi], whereas mitochondrial data affiliates it with the Semnopithecus clade. CONCLUSION: Neither relationships among the three langur genera nor their position within Asian colobines can be settled with 5 kb mitochondrial sequence data, but retroposon integrations confirm at least a common origin of Semnopithecus and Trachypithecus. According to Y chromosomal and 573 bp mitochondrial sequence data, T. [cristatus], T. [obscurus] and T. [francoisi] represent true members of the genus Trachypithecus, whereas T. [vetulus] clusters within Semnopithecus. Due to paraphyly of T. [vetulus] and polyphyly of Semnopithecus, a split of the genus into three species groups (S. entellus - North India, S. entellus - South India + T. johnii, S. entellus - Sri Lanka + T. vetulus) seems to be appropriate. T. [pileatus] posses an intermediate position between both genera, indicating that the species group might be the result of ancestral hybridization.

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Taxonomic Revision and Evolutionary Phylogeography of Dusky Langur (Trachypithecus obscurus) in Peninsular Malaysia.

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