Primates最新文献

Spider monkeys (Ateles sp.) are among the most endangered primates in tropical forests, ranging from Central to South America. The current consensus on their classification is split into 7 species. However, species identification of Ateles individuals is challenging because their intraspecific and interspecific morphological traits gradually change and diversify among species, especially in pelage color and patterning. This problem makes it challenging to perform conservation in both wild (in situ) and captive (ex situ) populations. Currently, there are approximately 150 captive spider monkeys in around 30 Japanese zoos, reflecting more than 120 years of generational changes. To understand the genetic structure of the Ateles population in Japan and promote its ex situ conservation, we performed a population genetic analysis. Genomic DNA was extracted from 127 individuals using their fresh hair follicles. We determined the nucleotide sequences of three mitochondrial DNA regions and the nucleotide lengths of nine nuclear microsatellite loci in all individuals. Our analysis revealed the maternal lineages of four species (A. chamek, A. fusciceps, A. geoffroyi, and A. hybridus) from mitochondrial DNA analysis, and we identified novel haplotypes not previously reported. By comparing the maternal lineages of each individual with zoos' breeding records, we discovered at least 29 hybrid individuals, comprising about 20% of the current Japanese population. The results of the nuclear microsatellite analysis confirmed the genetic structure of hybrid individuals and suggested the presence of additional hybrids that could not be identified based on maternal lineage analysis and zoos' breeding records alone. These findings can contribute to the more appropriate management of spider monkeys toward ex situ conservation.

Long-term monitoring data on population abundance and distribution are essential for developing and refining conservation strategies, particularly for endangered species like the proboscis monkey (Nasalis larvatus), for which data remain limited across much of their range in Borneo. Previous studies conducted in 2004/2005 and 2014 in the Klias Peninsula, western Sabah, northern Borneo, provided important insights into population trends and distribution. Building on this foundation, we reassessed the proboscis monkey population in 2022 after an 8-year interval and investigated changes in land use and land cover during the same period. Our findings indicate a lower overall estimate of population abundance (number of individuals); however, the number of observed groups is comparable to previous studies, suggesting some stability. Distribution patterns have remained relatively stable, with population strongholds in the central part of the Klias Peninsula, underscoring the continued importance of areas like Padas Damit Forest Reserve for proboscis monkey conservation. Our data also reveal concerning trends, including a decline in group sizes (number of individuals per group) within breeding units and the presence of very small populations in fragmented sites such as Bongawan, presenting ongoing conservation challenges. Our land-use and land-cover change findings further revealed that less than half of the available proboscis monkey habitats in this region are fully protected. Vegetation analysis showed that tree species richness positively influences proboscis monkey abundance, emphasizing the critical role of food resource diversity. These findings have important conservation implications for the long-term survival of this endangered primate in the Klias Peninsula region.

The evolutionary origins of caring for dead conspecifics are not completely understood. While nonhuman animals' understanding of changes in the state of a dead conspecific is debated, some exhibit behaviors consistent with experiencing emotional distress. Among nonhuman primates, the most common behavioral patterns related to the death of a group member include carrying and taking care of the deceased individual. The behavioral responses of the mother and other conspecifics towards a dead infant can be quantified to explore the underlying mechanisms and the evolutionary roots of these behaviors. Here, we report and quantify a probable case of infanticide in a wild group of capuchin monkeys, Sapajus xanthosternos, followed by the carrying and caring of the corpse by a primiparous mother. In our observation, the female maintained contact with the dead infant for 90% of the observed time, allowing other group members to approach and inspect the dead body, although only adult females and youngsters showed interest. The carrying of the corpse despite locomotion challenges, grooming and protecting it, and the apparent gradual adjustment to its unresponsive state (evidenced by unconventional carrying) suggest a potential coping strategy for dealing with the lack of feedback from the deceased. This study contributes to the field of comparative thanatology by documenting post-mortem behaviors in a primate species for which no prior record exists, broadening our understanding of such responses beyond humans.

The gut microbiome is now understood to play essential roles in host nutrition and health and has become a dominant research focus in primatology. Over the past decade, research has clarified the evolutionary traits that govern gut microbiome structure across species and the ecological traits that further influence consortia within them. Nevertheless, we stand to gain resolution by sampling hosts in understudied habitats. We focus on the lemurs of Madagascar's central highlands. Madagascar's highlands have a deep history as heterogeneous grassland-forest mosaics, but due to significant anthropogenic modification, have long been overlooked as lemur habitat. We collected fecal samples from Verreaux's sifakas (Propithecus verreauxi), common brown lemurs (Eulemur fulvus), and Goodman's mouse lemurs (Microcebus lehilahytsara) inhabiting two protected areas in the highlands and used amplicon sequencing to determine gut microbiome diversity and membership. As expected, the lemurs harbored distinct gut consortia tuned to their feeding strategies. Mouse lemurs harbored abundant Bifidobacterium and Alloprevotella that are implicated in gum metabolism, sifakas harbored abundant Lachnospiraceae that are implicated in leaf-fiber metabolism, and brown lemurs harbored diverse consortia with abundant WCBH1-41 that could be associated with frugivory in harsh seasons and habitats. Within brown lemurs, a suite of bacteria varied between seed-packed and leaf-packed feces, a proxy for dietary intakes, collected from the same group over days. Our results underscore the evolutionary and ecological factors that govern primate gut microbiomes. More broadly, we showcase the forests of Madagascar's central highlands as rich habitat for future research of lemur ecology and evolution.

Taxonomic classifications of the gracile capuchin monkeys, Cebus, have traditionally been based on cranio-dental and pelage characters. Advances in molecular biology have provided information on the evolutionary history of the genus but the taxonomy and distribution limits of taxa in the northern Andes are still under debate. To assess morphometric disparities and compare the results with hypotheses based on genetic evidence for Cebus taxonomy, we used 2D geometric morphometrics on 206 adult specimens (127 males, 77 females, 2 unsexed) belonging to 12 taxa by assigning Type I landmarks in the frontal (11), lateral (18) and ventral (16) views of the skull, and 14 in the mandible. Our results show that skull shape is more variable than centroid size and that morphometric disparities exist across and within all three geographic groups (Central America, Andes, and Amazon). Although skull shape in Cebus tends to vary slightly, our results suggest differences among some taxa and highlight the utility of studying shape in addition to methods that have focused on size. Some results concur with the taxonomic classifications based on molecular evidence but it is important to note that Cebus species are wide-ranging with high inter- and intraspecific phenotypic variability in diverse ecological conditions. This makes it difficult to provide species diagnoses based just on morphometric or morphological characters and suggests the need to integrate different sources of evidence to resolve uncertainties about the taxonomy and the evolutionary relationships in the genus.

The selection of sleeping sites of animals provide valuable insights into their adaptations to a changing environment. We collected data on the sleeping sites used by a group of François' langurs (Trachypithecus francoisi) from September 2005 to August 2006 at the Nonggang National Nature Reserve in southwest China. Our results showed that the langurs utilized four sleeping sites on cliffs throughout the year. They foraged in the feeding patches close to their sleeping sites, showing a multiple central place foraging strategy. Notably, two sleeping sites were predominantly used during the dry season with least available young leaves and fruits, suggesting food seasonality may have a significant impact on the sleeping sites utilization. Moreover, the langurs used the sleeping sites in the peripheral area less than expected. They repeatedly and continuously slept at the Site 1, with a frequency of 79.8% of all recorded sleeping nights, and a maximum of eight consecutive nights. In conclusion, the sleeping site choices of François' langurs are mainly influenced by dietary factors, rather than range and resource defense, predator avoidance, thermoregulation, or parasite avoidance. This study highlights the significance of food resource and foraging efficiency to karst-dwelling François' langurs when selecting sleeping sites.

Drawings serve as a profound medium of expression for both humans and apes, offering unique insights into the cognitive and emotional landscapes of the artists, regardless of their species. This study employs artificial intelligence (AI), specifically Convolutional Neural Networks (CNNs) and the interpretability tool Captum, to analyse non-figurative drawings by Molly, an orangutan. The research utilizes VGG19 and ResNet18 models to decode seasonal nuances in the drawings, achieving notable accuracy in seasonal classification and revealing complex influences beyond human-centric methods. Techniques, such as occlusion, integrated gradients, PCA, t-SNE, and Louvain clustering, highlight critical areas and elements influencing seasonal recognition, providing deeper insights into the drawings. This approach not only advances the analysis of non-human art but also demonstrates the potential of AI to enrich our understanding of non-human cognitive and emotional expressions, with significant implications for fields like evolutionary anthropology and comparative psychology.

Interspecies interactions present diverse forms and functions, contributing significantly to ecological and social dynamics. This study focuses on the mounting behaviours of Japanese macaques (Macaca fuscata) towards Sika deer (Cervus nippon), a rare and still unexplained phenomenon, with minimal emphasis on the behaviour of the deer. Using video data from two distinct sites, Yakushima and Minoh, Japan, we documented 45 sequences of macaque-deer interactions and analysed macaques' behaviours and deer behaviours using focal and behavioural sampling techniques. We identified four primary activities performed by macaques during mountings-sexual, play, grooming, and resting-with resting being predominant. The study evaluates six hypotheses regarding the functions of these mounting behaviours: (1) interactions are sex-specific, (2) macaques use deer for transportation, (3) mutual warming through physical contact occurs, (4) deer provide support for resting, (5) macaques engage in grooming to consume parasites or play to strengthen interspecies bonds, and (6) aggressive signals relate to resource disputes or rejection of mounting behaviour. Statistical analyses using the Kruskal-Wallis test and Dunn's post-hoc test revealed significant differences between resting and other active behaviours, but no significant differences in behaviour duration between lying and sitting positions. Adults engaged in mounting for longer periods than juveniles, suggesting potential age-related differences in social and reproductive roles. These findings enhance our understanding of interspecies interactions by focusing on macaque behaviours and emphasise the need for longitudinal studies to clarify the ecological and social implications of these interactions.