Sleeping site and tree selection by Sichuan snub-nosed monkeys (Rhinopithecus roxellana) in Baihe Nature Reserve, Sichuan, China

Adaptations to a cold climate promoted social evolution in Asian colobine primates

The biological mechanisms that underpin primate social evolution remain poorly understood. Asian colobines display a range of social organizations, which makes them good models for investigating social evolution. By integrating ecological, geological, fossil, behavioral, and genomic analyses, we found that colobine primates that inhabit colder environments tend to live in larger, more complex groups. Specifically, glacial periods during the past 6 million years promoted the selection of genes involved in cold-related energy metabolism and neurohormonal regulation. More-efficient dopamine and oxytocin pathways developed in odd-nosed monkeys, which may have favored the prolongation of maternal care and lactation, increasing infant survival in cold environments. These adaptive changes appear to have strengthened interindividual affiliation, increased male-male tolerance, and facilitated the stepwise aggregation from independent one-male groups to large multilevel societies.

Epidemiological Survey and Risk Factor Analysis of 14 Potential Pathogens in Golden Snub-Nosed Monkeys at Shennongjia National Nature Reserve, China

Golden snub-nosed monkeys (Rhinopithecus roxellanae) belong to Class A, the highest level of endangered primate species. Exploring the infection status of potential pathogens in golden snub-nosed monkeys is important for controlling associated diseases and protecting this species. The objective of this study was to investigate the seroprevalence for a number of potential pathogens and the prevalence of fecal adenovirus and rotavirus. A total of 283 fecal samples were collected from 100 golden snub-nosed monkeys in December 2014, June 2015, and January 2016; 26 blood samples were collected from 26 monkeys in June 2014, June 2015, January 2016 and November 2016 at Shennongjia National Reserve in Hubei, China. The infection of 11 potential viral diseases was examined serologically using an Indirect Enzyme-linked Immunosorbent Assay (iELISA) and Dot Immunobinding Assays (DIA), while the whole blood IFN-γ in vitro release assay was used to test tuberculosis (TB). In addition, fecal Adenovirus and Rotavirus were detected using Polymerase Chain Reaction (PCR). As a result, the Macacine herpesvirus-1 (MaHV-1), Golden snub-nosed monkey cytomegalovirus (GsmCMV), Simian foamy virus (SFV) and Hepatitis A virus (HAV) were detected with the seroprevalence of 57.7% (95% CI: 36.9, 76.6), 38.5% (95% CI: 20.2, 59.4), 26.9% (95% CI: 11.6, 47.8), and 7.7% (95% CI: 0.0, 84.2), respectively. Two fecal samples tested positive for Adenovirus (ADV) by PCR, with a prevalence of 0.7% (95% CI: 0.2, 2.5), and further, the amplification products were sequenced. Phylogenetic analysis revealed that they belonged to the HADV-G group. However, other pathogens, such as Coxsackievirus (CV), Measles virus (MeV), Rotavirus (RV), Simian immunodeficiency virus (SIV), Simian type D retroviruses (SRV), Simian-T-cell lymphotropic virus type 1 (STLV-1), Simian varicella virus (SVV), Simian virus 40 (SV40) and Mycobacterium tuberculosis complex (TB) were negative in all samples. In addition, a risk factor analysis indicated that the seroprevalence of MaHV-1 infection was significantly associated with old age (≥4 years). These results have important implications for understanding the health status and conservation of the endangered golden snub-nosed monkey population at Shennongjia Nature Reserve.

Food provisioning results in functional, but not compositional, convergence of the gut microbiomes of two wild Rhinopithecus species: Evidence of functional redundancy in the gut microbiome

The consumption of similar diets has led to the convergence of gut microbial compositions and functions across phylogenetically distinct animals. However, given the functional redundancy in gut microbiomes, it remains unclear whether synchrony occurs in their functions only and not in their composition, even within phylogenetically close animals consuming a similar diet. In this study, we collected fresh fecal samples from a Rhinopithecus roxellana population in April 2021 (before food provisioning) and June and December 2021 (after food provisioning) and used high-throughput sequencing methods (full-length 16S rRNA gene sequencing and metagenomes) to investigate changes in the gut microbiome due to food provisioning. Combining the results from our previous studies on a wild Rhinopithecus bieti population, we found that the artificial food provisions (e.g., apples, carrots, and peanuts) affected the gut microbiome, and synchrony occurred only in its functions and antibiotic resistance gene community in both Rhinopithecus species, reflecting its ecological functional redundancy. Given the current findings (e.g., depletion in probiotic microbes, dysbiosis in the gut microbial community, and changes in the antibiotic resistance gene profile), anthropogenic disturbances (e.g., food provisioning) would have potential negative effects on host health. Therefore, human activity in animal conservation should be rethought from the standpoint of gut microbial diversity.

The Influence of Environmental Variables on Home Range Size and Use in the Golden Snub-Nosed Monkey (Rhinopithecus roxellana) in Tangjiahe National Nature Reserve, China

Accurate descriptions of home ranges can provide important information for understanding animal ecology and behavior and contribute to the formulation of conservation strategies. We used the grid cell method and kernel density estimation (KDE) to estimate the home range size of golden snub-nosed monkeys (Rhinopithecus roxellana) in Tangjiahe National Nature Reserve. We also used Moran’s eigenvector maps analysis and variation partitioning to test the influence of environmental variables on home range use. The seasonal home range size was 15.4 km2 in spring, 11.6 km2 in summer, 13.7 km2 in autumn, and 15.6 km2 in winter, based on the grid cell method. The seasonal core area of 50% KDE was 9.86 km2 in spring, 5.58 km2 in summer, 7.20 km2 in autumn, and 4.23 km2 in winter. The environmental variables explained 63.60% of home range use intensity in spring, 72.21% in summer, 26.52% in autumn, and none in winter, and some environmental variables contributed to the spatial variation in home range use intensity. Water sources, tree density, and dominant trees of Chinese wingnut (Pterocarya stenoptera) were the important environmental factors determining home range use. These environmental factors require protection to ensure the survival of the golden snub-nosed monkey.

Sleeping Site and Tree Selection by Bale Monkeys (Chlorocebus djamdjamensis) at Kokosa Forest Fragment in Southern Ethiopia

Although selecting advantageous sleeping sites is crucial for nonhuman primates, the extent to which different factors contribute to their selection remains largely unknown for many species. We investigated hypotheses relating to predator avoidance, food access, and thermoregulation to explain the sleeping behavior of Bale monkeys (Chlorocebus djamdjamensis) occupying a degraded fragmented forest, Kokosa, in the southern Ethiopian Highlands. We found that the study group reused 11 out of 20 sleeping sites used during the 42 study days over a 6-month period. Sleeping sites were usually close to the last feeding trees of the day (mean distance =15.2 m) and/or the first feeding trees of the next morning (mean distance = 13.5 m). This may reflect an attempt to maximize feeding efficiency and reduce travel costs. Compared to the mean trees in the study area, sleeping trees were significantly shorter. Bale monkeys selected sleeping places in trees with high foliage density above and below them, lending support to the hypothesis that they select sleeping places that can conceal them from predators and at the same time offer shelter from cold weather. The monkeys also frequently huddled at night. Our results suggest that predator avoidance, access to food resources, and thermoregulation all likely influence the selection of sleeping sites by Bale monkeys.

Suitable habitat prediction of Sichuan snub-nosed monkeys (Rhinopithecus roxellana) and its implications for conservation in Baihe Nature Reserve, Sichuan, China

As an endemic primate species with one of the highest priorities in wildlife conservation in China, Sichuan snub-nosed monkeys (Rhinopithecus roxellana) have undergone a sharp decline and range reduction in recent centuries. Here, we used maximum entropy modelling (MaxEnt) integrated with four types of environmental variables, including three biological climate variables (Bio17, precipitation of the driest quarter; Bio6, min. temperature of the coldest month; and Bio2, mean diurnal range), three topographic variables (altitude, slope, and aspect), two anthropogenic variables (Human Footprint Index and human disturbance), and three vegetation-related variables (enhanced vegetation index, normalized difference vegetation index, and Wet Index) to identify the spatial distribution of suitable habitats for Sichuan snub-nosed monkeys in Baihe Nature Reserve (BNR), which is located in the Minshan Mountains. The average training AUC of our model performance is 0.929 ± 0.003. The model predicted 9.6 km² of high suitability habitats and 14.1 km² of moderate suitability habitats for Sichuan snub-nosed monkeys, adding up to only 11.7% of the total area of concern for the study in the BNR. The top four variables ranked in the model (altitude, Human Footprint Index, human disturbance, and Bio17) accounted for relative gain contributions of 23.3%, 19.3%, 14.2%, and 13.4%, respectively. The predicted suitable habitats were confined to an altitude range of 1971-3198 m, Human Footprint Index of mainly 3-5 values, low human disturbance (mainly livestock), and precipitation of the driest (or coldest) quarter of 9-22 mm. Additionally, the suitable habitats were mainly distributed in the core zone (36.1%), buffer zone (26.8%), and experimental zone (29.5%). The remaining habitats (7.6%) were distributed in the 0.5-km buffer zone of the reserve border. The predicted suitable habitats indicated limited suitable habitat space for the Sichuan snub-nosed monkeys, with most of the suitable habitat distributed outside the core zone in the BNR. Our findings highlighted that human activities in all three functional zones could be the most negative factor on suitable habitat distribution of Sichuan snub-nosed monkeys in the BNR.