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Trachypithecus, which currently contains 20 species divided into four groups, is the most speciose and geographically dispersed genus among Asian colobines. Despite several morphological and molecular studies, however, its evolutionary history and phylogeography remain poorly understood. Phayre's langur (Trachypithecus phayrei) is one of the most widespread members of the genus, but details on its actual distribution and intraspecific taxonomy are limited and controversial. Thus, to elucidate the evolutionary history of Trachypithecus and to clarify the intraspecific taxonomy and distribution of T. phayrei, we sequenced 41 mitochondrial genomes from georeferenced fecal samples and museum specimens, including two holotypes. Phylogenetic analyses revealed a robustly supported phylogeny of Trachypithecus, suggesting that the T. pileatus group branched first, followed by the T. francoisi group, and the T. cristatus and T. obscurus groups most recently. The four species groups diverged from each other 4.5-3.1 million years ago (Ma), while speciation events within these groups occurred much more recently (1.6-0.3 Ma). Within T. phayrei, we found three clades that diverged 1.0-0.9 Ma, indicating the existence of three rather than two taxa. Following the phylogenetic species concept and based on genetic, morphological, and ecological differences, we elevate the T. phayrei subspecies to species level, describe a new species from central Myanmar, and refine the distribution of the three taxa. Overall, our study highlights the importance of museum specimens and provides new insights not only into the evolutionary history of T. phayrei but the entire Trachypithecus genus as well.

Knowledge of the physiological and morphological evolution and adaptation of nonhuman primates is critical to understand hominin origins, physiological ecology, morphological evolution, and applications in biomedicine. Particularly, limestone langurs represent a direct example of adaptations to the challenges of exploiting a high calcium and harsh environment. Here, we report a de novo genome assembly (Tfra_2.0) of a male François’s langur (Trachypithecus francoisi) with contig N50 of 16.3 Mb and resequencing data of 23 individuals representing five limestone and four forest langur species. Comparative genomics reveals evidence for functional evolution in genes and gene families related to calcium signaling in the limestone langur genome, probably as an adaptation to naturally occurring high calcium levels present in water and plant resources in karst habitats. The genomic and functional analyses suggest that a single point mutation (Lys1905Arg) in the α1c subunit of the L-type voltage-gated calcium channel Cav1.2 (CACNA1C) attenuates the inward calcium current into the cells in vitro. Population genomic analyses and RNA-sequencing indicate that EDNRB is less expressed in white tail hair follicles of the white-headed langur (T. leucocephalus) compared with the black-colored François’s langur and hence might be responsible for species-specific differences in body coloration. Our findings contribute to a new understanding of gene–environment interactions and physiomorphological adaptative mechanisms in ecologically specialized primate taxa.

Characterizing the feeding ecology of threatened species is essential to establish appropriate conservation strategies. We focused our study on the proboscis monkey ( Nasalis larvatus ), an endangered primate species which is endemic to the island of Borneo. Our survey was conducted in the Lower Kinabatangan Wildlife Sanctuary (LKWS), a riverine protected area that is surrounded by oil palm plantations. We aimed to determine the diet of multiple proboscis monkey groups by using two methods. First, we conducted boat-based direct observations (scan and ad libitum sampling) and identified 67 plant species consumed by the monkeys at their sleeping sites in early mornings and late afternoons. Secondly, we used the DNA metabarcoding approach, based on next-generation sequencing (NGS, MiSeq Illumina) of faecal samples (n = 155), using the short chloroplast sequence, the trnL (UAA) P6 loop. In addition, we built a DNA reference database with the local plants available in the LKWS. When combining feeding data from both methods, we reported a diverse dietary ecology in proboscis monkeys, with at least 89 consumed plant taxa, belonging to 76 genera and 45 families. Moreover, we were able to add 22 new genera as part of the diet of this endangered colobine primate in the LKWS. The two methods provided congruent and complementary results, both having their advantages and limitations. This study contributed to enhance the knowledge on the feeding ecology of proboscis monkeys, highlighting the significance of several plant species that should further be considered in habitat restoration plans or corridor establishment.

Hybridization is increasingly recognized as an important mechanism of evolutionary change in the order Primates. Here, we present the first observational data supporting natural hybridization between the critically endangered purple-faced langur (Semnopithecus vetulus philbricki) and the threatened tufted gray langur (Semnopithecus priam thersites) in Kaludiyapokuna Forest Reserve in Sri Lanka. In one case study, we observed a long-term (> 1 year) mixed-species group consisting of one adult tufted gray langur male coexisting with seven adult purple-faced females. Although copulations were not observed, two infants were conceived during the male’s tenure, and the coat color of one of these infants transitioned into that intermediate between those of the two langur species. The tufted gray langur male was also aggressive toward extra-group males of both species, as well as towards purple-faced juveniles within his group. However, we never witnessed the male exhibiting aggression towards the infants conceived during his tenure. In a second case study, a female purple-faced langur visited and sexually solicited a tufted gray langur male in a known study group of this species over the course of 2 days, in what resembled a sexual consortship. Taken together, the observed mixed-species association and attempted interspecific mating suggest that hybridization is very likely in these sympatric species. Genetic data are needed to confirm and determine the extent of hybridization in the dry zone of Sri Lanka where purple-faced langurs live in sympatry with tufted gray langurs.

Zoologist Zuofu Xiang’s research in Asia helps governments to protect the populations and teaches him the value of cooperation. Zoologist Zuofu Xiang’s research in Asia helps governments to protect the populations and teaches him the value of cooperation. Credit: Zuofu Xiang Dr Zuofu Xiang sat on the ground interacting with snub nosed monkeys, Baimaxueshan Nature Reserve, Yunnan, China

Background Snub-nosed monkeys are highly endangered primates and their population continues to decline with the habitat fragmentation. Artificial feeding and breeding is an important auxiliary conservation strategy. Studies have shown that changes and imbalances in the gut microbiota often cause gastrointestinal problems in captive snub-nosed monkeys. Here, we compare the gut microbiota composition, diversity, and predicted metabolic function of three endangered species of snub-nosed monkeys ( Rhinopithecus bieti , R. brelichi , and R. roxellana ) under the same captive conditions to further our understanding of the microbiota of these endangered primates and inform captive conservation strategies. 16 S rRNA gene sequencing was performed on fecal samples from 15 individuals ( R. bieti N = 5, R. brelichi N = 5, R. roxellana N = 5). Results The results showed that the three Rhinopithecus species shared 24.70% of their amplicon sequence variants (ASVs), indicating that the composition of the gut microbiota varied among the three Rhinopithecus species. The phyla Firmicutes and Bacteroidetes represented 69.74% and 18.45% of the core microbiota. In particular, analysis of microbiota diversity and predicted metabolic function revealed a profound impact of host species on the gut microbiota. At the genus level, significant enrichment of cellulolytic genera including Rikenellaceae RC9 gut group , Ruminococcus , Christensenellaceae R7 group , UCG 004 from Erysipelatoclostridiaceae, and UCG 002 and UCG 005 from Oscillospiraceae, and carbohydrate metabolism including propionate and butyrate metabolic pathways in the gut of R. bieti indicated that R. bieti potentially has a stronger ability to use plant fibers as energy substances. Bacteroides , unclassified Muribaculaceae , Treponema , and unclassified Eubacterium coprostanoligenes group were significantly enriched in R. brelichi . Prevotella 9 , unclassified Lachnospiraceae , and unclassified UCG 010 from Oscillospirales UCG 010 were significantly enriched in R. roxellana . Among the predicted secondary metabolic pathways, the glycan biosynthesis and metabolism had significantly higher relative abundance in the gut of R. brelichi and R. roxellana than in the gut of R. bieti . The above results suggest that different Rhinopithecus species may have different strategies for carbohydrate metabolism. The Principal coordinate analysis (PCoA) and Unweighted pair-group method with arithmetic mean (UPGMA) clustering tree revealed fewer differences between the gut microbiota of R. brelichi and R. roxellana . Correspondingly, no differences were detected in the relative abundances of functional genes between the two Rhinopithecus species. Conclusion Taken together, the study highlights that host species have an effect on the composition and function of the gut microbiota of snub-nosed monkeys. Therefore, the host species should be considered when developing nutritional strategies and investigating the effects of niche on the gut microbiota of snub-nosed monkeys.

Maternal caretaking and transport of dead infants are widespread among nonhuman primates, having been reported in numerous species of monkeys and apes. By contrast, accounts of such behaviors toward dead juveniles are scarce. Here, we describe responses by the mother and other group members to the death of a juvenile in a wild, multi-level group of Sichuan snub-nosed monkeys ( Rhinopithecus roxellana ). Following the juvenile’s fatal accident, his mother transported and cared for the corpse for four days. Immature monkeys belonging to the same one-male unit, and some individuals from other social units also showed interest in and tended the corpse. Comparisons of this case with those involving the deaths of infants and an adult female in the same population highlight possible effects of physiological, psychological and emotional factors in primate thanatological responses, and provide an additional perspective on the origin and evolution of compassionate acts.

Urbanization has drastically altered natural habitats, forcing non-human primates (NHPs) to adapt to human-modified environments. This study examines one such adaptation undertaken by free-ranging Hanuman langurs residing in Dakshineswar, a temple area and a tourist hub in West Bengal. Our observations reveal that they have come up with solicitation behaviors resembling human begging wherein they ask for food from nearby humans using various gestures. Notably, we identified seven distinct ‘begging’ gestures, with those involving embracing human legs and pulling their clothes having strong correlation with successful outcome. Moreover, adult female langurs predominantly initiate such gestures, with successful solicitation events peaking during evening sessions. The findings underscore langurs' adaptive capacity to exploit anthropogenic resources, where they have started to associate human beings as their food source. This study sheds light on primate behavior in urban landscapes, adding further evidence to the complex dynamics of human-monkey interactions .

Background The snub-nosed monkey ( Rhinopithecus roxellanae ) is an endangered animal species mainly distributed in China and needs to be protected. Gut microbiome is an important determinant of animal health and population survival as it affects the adaptation of the animals to different foods and environments under kinetic changes of intrinsic and extrinsic factors. Therefore, this study aimed to elucidate gut fecal microbiome profiles of snub-nosed monkeys affected by several extrinsic and intrinsic factors, including raising patterns (captive vs. wild), age, sex, and diarrheal status to provide a reference for making protection strategies. Results The 16S rRNA gene sequencing was firstly used to pre-check clustering of 38 fecal samples from the monkeys including 30 wild and 8 captive (5 healthy and 3 diarrheal) from three Regions of Shennongjia Nature Reserve, Hubei Province, China. Then the 24 samples with high-quality DNA from 18 wild and 6 captive (4 healthy and 2 diarrheal) monkeys were subjected to shotgun metagenomic sequencing to characterize bacterial gut microbial communities. We discovered that the raising pattern (captive and wild) rather than age and sex was the predominant factor attributed to gut microbiome structure and proportionality. Wild monkeys had significantly higher bacterial diversity and lower Bacteroidetes/Firmicutes ratios than captive animals. Moreover, the gut microbiomes in wild healthy monkeys were enriched for the genes involved in fatty acid production, while in captive animals, genes were enriched for vitamin biosynthesis and metabolism and amino acid biosynthesis from carbohydrate intermediates. Additionally, a total of 37 antibiotic resistant genes (ARG) types were detected. Unlike the microbiome diversity, the captive monkeys have a higher diversity of ARG than the wild animals. Conclusion Taken together, we highlight the importance of self-reprogramed metabolism in the snub-nosed monkey gut microbiome to help captive and wild monkeys adapt to different intrinsic and extrinsic environmental change.

Primate populations are under threat due to human activities, like illegal trafficking, requiring conservation efforts such as reintroduction programs. However, these initiatives often encounter challenges, such as aspects of individual behavior related to movement and foraging. The presence of experienced conspecifics has been suggested to improve the success of these programs. This study focuses on woolly monkeys and examines how the presence of experienced conspecifics influences the performance of reintroduced individuals. Focal animal sampling was used to collect data on proximity, diet composition, home range, and use of vertical strata of three groups of reintroduced woolly monkeys. Data was analyzed for the first 2 and 6 months after release of individuals. The results reveal that the involvement of experienced conspecifics speeds up the process of adaptation, particularly in terms of diet diversity and spatial utilization; however, differences in individual responses were also prevalent. Our findings highlight the importance of incorporating individuals with prior wild experience into reintroduction groups for improving the likelihood of success. Additionally, the study underscores the role of social learning in captive management practices, aiding in post-release behavioral adaptation and survival. This research offers valuable insights for primate conservation, emphasizing the significance of considering the presence of experienced individuals and possible social learning processes in the planning and execution of effective reintroduction efforts.