American Journal of Primatology最新文献

In the wild, non-human primates may experience population declines resulting from low genetic diversity and inbreeding, while the scientific planning of ecological corridors can assist in population recovery and mitigate genetic diversity loss. The Hainan Gibbon (Nomascus hainanus) is the world's most endangered primate, endemic to Hainan Island in extreme southern China. Recent conservation efforts have successfully increased the number of Hainan Gibbon individuals to more than three times that of 20 years ago and six times that of 50 years ago. Updated information on population genetic diversity is urgently needed. In this study, we collected fresh fecal samples from 25 individuals in five family groups (A, B, C, D, and E) of Hainan Gibbon using a non-invasive sampling method. We then evaluated and compared the variations in genetic diversity in Hainan Gibbon using 10 microsatellite loci. The sex identification experiment showed that the female-to-male ratio of the existing Hainan Gibbon population was 1:1.27. The population is still at a genetic bottleneck. Its dispersal mode is bisexual, and Hainan Gibbon tend to mate with individuals who have lower-than-average genetic relationships with themselves. The level of genetic diversity in family groups D and E was relatively low, while the genetic distance of D and E from family groups A, B, and C was relatively large. Currently, the Hainan Gibbon population exhibits no detectable genetic differentiation. With an effective population size of merely 13 individuals (95% confidence interval: 5.1–49.9), this critically endangered species remains at imminent risk of extinction. We suggest developing an ecological corridor between family groups A and E, which have a relatively large genetic distance.

The Caribbean Primate Research Center's (CPRC) specific-pathogen-free (SPF) rhesus macaque (Macaca mulatta) colony was established between 1998 and 2002 with 87 founders from Cayo Santiago. Colony expansion continued with the rederivation of animals from their SPF predecessors, while additional animals were still being relocated from Cayo Santiago. The CPRC's major histocompatibility complex (MHC) database, generated through next-generation short-read sequencing, provides insights into the long-term MHC immunogenetics of its SPF colony. This database was used to examine the composition of Mamu-A, Mamu-B (Class I), and Mamu-DRB (Class II) across five 5-year SPF birth cohorts from 1998 to 2022. Population structure at these loci was compared with that of 27 non-syntenic short tandem repeats (STRs) to examine longitudinal differences in MHC and STR composition during the colony's transition from establishment to expansion. There was no significant relationship between the average observed (OH) and expected (EH) heterozygosity values of the STRs and those of the MHC. STRs exhibited greater and more consistent heterogeneity. Besides being lower than the STRs, the longitudinal changes in the MHC's EH were more pronounced. The pattern of pairwise differentiation (F_ST) at the MHC differed significantly from that of the STRs, where the MHC showed greater differentiation between birth cohorts, whereas STR differentiation was negligible. Increasing rederivation from SPF predecessors while reducing Cayo Santiago translocations made subsequent birth cohorts more genetically divergent and less heterogeneous at the MHC. Recruitment strategies are the primary driver of longitudinal diversity patterns at the MHC, while variation at non‑syntenic STRs was uncorrelated with MHC diversity. This divergence in STR and MHC variation underscores that MHC loci remain under selection even in a genetically managed population, highlighting the importance of direct MHC assessment and considering both MHC and STR diversity in management decisions.

The Himalayan Kashmir langur (Semnopithecus ajax) is an endangered colobine of the northwestern Himalayas, occurring in India and Pakistan; yet its ecology remains poorly studied. In Pakistan, it is known from Azad Jammu and Kashmir (AJK) and the northern districts of Khyber Pakhtunkhwa (KPK) but populations restricted to KPK has been neglected until the data. In this regard, we conducted 60 line-transect surveys (118.2 km) across 69.5 km² in three KPK districts—Mansehra, Kohistan, and Battagram—to estimate population density and abundance. Further, we modeled habitat suitability and connectivity modeling of langurs across its known range in Pakistan. The current study revealed mean density across the surveyed districts was 4.5 individuals/km² (95% CI: 2.3–6.7), with substantially higher densities in Mansehra (7.4; 95% CI: 3.3–11.5) compared to Kohistan–Battagram (KB) (1.3; 95% CI: 0.1–2.5). The total population in the study area was estimated at 314 individuals (95% CI: 143–485), with ~86% concentrated in Mansehra. Habitat suitability modeling (AUC = 0.96) identified four major suitable niche zones (SNZ) (~2,953 km²) across Pakistan, primarily montane forests between 1,300–3,100 m with > 40% canopy cover, though only ~82 km² (~1%) overlapped with existing protected areas. Connectivity analysis indicated forested corridors linking these niche zones, while fragmentation reduced connectivity in several regions. Our findings demonstrate that the langur persists in Pakistan as a small, fragmented, and forest-dependent population. Conservation of this threatened species will require improved forest protection, management of habitat corridors, and coordinated transboundary conservation efforts across its Himalayan range.

Ecological variables such as climate and habitat composition can impact the infection patterns of gastrointestinal parasites in animal host populations by affecting host behavior and parasite survivability and distribution in the external environment. Data from wild primate populations provide insights into these processes. To contribute new insights from a well-characterized population, we collected 200 fecal samples from five groups of Costa Rican capuchin monkeys from August 2020 to August 2021 and screened them for gastrointestinal parasites. We estimated annual home range sizes for the groups and used satellite imagery to measure forest productivity (via Normalized Difference Vegetation Index) and forest cover within their home ranges. We also measured total monthly rainfall and average monthly temperature at the field site to explore the effects of local climate on parasitism. We used Bayesian regression models to examine the effects of these ecological variables on parasite richness, fecal parasite density, and parasite presence. We found that rainfall, and to a lesser extent, temperature, affected the presence and fecal density of certain parasitic taxa. The presence of the soil-transmitted helminth Strongyloides decreased in both hotter and rainier months, and hosts shed fewer Strongyloides eggs during hotter months. Infections with indirectly transmitted parasites (e.g., Prosthenorchis sp., Hymenolepis sp.) were more common during drier months. This corresponds with times when fruit availability is lower and invertebrate consumption is higher at this site. These findings highlight the relationship between climate and patterns of parasitic infection in hosts, likely reflecting changes in host diet, behavior, and parasite abundance.

Mapping habitat utilization at fine spatio-temporal scales is essential for understanding various aspects of animal ecology, and for the conservation and management of animal species. A unified approach incorporating habitat structure, composition, and animal activities is necessary for such fine-scale assessments. Here, we introduce a unified activity-based habitat utilization model based on simulations of habitat structure and composition, and map the fine-scale spatio-temporal habitat utilization of an endangered canopy dwelling primate inhabiting the Western Ghats, the lion-tailed macaque (Macaca silenus). From our simulations, we found that habitat utilization predictions will be enhanced when tree distribution and abundance are combined with height utilization data, compared to when they were assessed independently. This simulation study indicates that for all activities, primary forests provide more suitable habitats for lion-tailed macaques than plantations. Seasonal variation was observed in habitat suitability due to seasonality in the fruiting of trees, as plantations provided more suitable habitats during monsoon, while primary forests provided more suitable habitats in post monsoon and summer. We observed no locomotion routes with contiguous canopy connectivity in plantations, whereas such routes were common in forests. Our simulation-based model has implications for understanding many aspects of arboreal ecology, as it incorporates habitat structure and composition. Overall, our simulations reveal that incorporating habitat structure and composition is important for understanding fine-scale spatio-temporal habitat utilization of arboreal species, and it can be utilized for the conservation of primates inhabiting tropical habitats, where the collection of field data on trees for large areas can be demanding.