American Journal of Primatology最新文献

Acoustic communication is important for social cohesion and territory defense in forest primates, including the endangered lion tamarins (genus Leontopithecus). Although vocalizations of individual species have been studied, there is still no comparative analysis examining whether acoustic parameters can reliably distinguish among all four species. We hypothesized that species-specific differences in acoustic features allow discrimination among lion tamarin species, and we predicted that both spectral and temporal parameters would reveal interspecific variation. To test this, we analyzed seven shared vocalizations (long calls, whines, trills, rasps, clucks, tsicks, and peeps) from the black-faced lion tamarin (Leontopithecus caissara), golden lion tamarin (Leontopithecus rosalia), golden-headed lion tamarin (Leontopithecus chrysomelas), and black lion tamarin (Leontopithecus chrysopygus). Acoustic data were obtained from online sound libraries and analyzed using Raven Pro software. Spectral and temporal parameters, including frequency at 5% and 95%, peak frequency, center frequency, and bandwidth 90% were measured, followed by principal component analysis (PCA) and nonparametric statistical tests to identify species-specific differences. Our results revealed significant interspecific differences across multiple vocalizations, with spectral parameters being the most relevant for distinguishing species, whereas temporal parameters contributed less. L. caissara emerged as the most acoustically distinct species, while L. rosalia and L. chrysopygus exhibited the greatest vocal similarity. In conclusion, this study provides the first comparative analysis of seven vocalization types across all four lion tamarin species, establishing an acoustic baseline, confirming the importance of spectral parameters for species differentiation, and demonstrating the potential of vocalizations for conservation applications.

Allochthonous species can negatively impact biodiversity by introducing new pathogens, intensifying competition for resources, promoting habitat changes, and causing ecosystem disruption. Introduced species can also spread into areas designated for the conservation of native species. This colonization and, eventually, contact between historically isolated lineages can cause hybridization, resulting in decreased offspring fitness or, conversely, promoting hybrid vigor, threatening the integrity of native populations and increasing their risk of extinction. Here, we analyzed an allochthonous population from a fragment of Brazilian Atlantic Forest, where both endangered Golden-headed lion tamarins and Golden lion tamarins were illegally introduced into the natural range of the Golden lion tamarin in the 1990s. We performed Genotyping by Sequencing and complementary mitochondrial analysis to investigate hybridization and to assess the genetic diversity and structure of the invasive population. Our results were able to rule out the existence of hybrids among the samples analyzed, providing relevant information about the genetic diversity of the alien population and effectively contributing to conservation programs and management actions for both species. Conservation actions and effective surveillance policies to prevent new illegal introductions should be mandatory to ensure the protection of these threatened charismatic species which are targets of illegal trade and trafficking.

The early developmental period plays a key role in primate behavioral outcomes. Understanding the behavioral ecology of infant indris (Indri indri) helps to identify resources needed during early developmental stages, the weaning process, and the role of mothers in developing infants' survival abilities. In this study, we investigated the behavioral and dietary development of wild Indri indri in Madagascar. We found that infants undergo significant behavioral transitions during their early growth, which reflect their maturation and adaptation to the environment. Play is critical in developing locomotion skills and acquiring knowledge about dietary preferences. Social interactions, initially centered on grooming with the mother, began to extend to other group members as early as 4 months of age, reflecting a shift from maternal care to broader social bonding. Additionally, territorial behaviors such as scent marking became more prominent in later month age classes when new behaviors, such as singing, emerged. We observed a co-feeding relationship between young indris and their mothers that ceased around 1 year of age. Lauraceae was the most-eaten plant family in the first 2 years of life, and we observed shifts in plant taxa and plant parts consumption with age. Milk consumption was not observed after 7 months of age. We also highlighted the presence of coprophagy and geophagy in indri infants, which were observed on several occasions consuming maternal feces and soil. These behaviors could play a role in maternal microbiota inoculation and toxin regulation, though further evidence is needed, even at a young age. Our work highlighted the dietary requirements and behavioral development of indri infants. These Critically Endangered lemurs have never been bred in captivity; our findings provide foundational data to inform future studies and potential conservation strategies.

Endemic to the island of Madagascar, the enigmatic aye-aye is amongst the most endangered primates on the planet. Due to their nocturnal and arboreal lifestyle and large geographic ranges, much remains unknown about these lemurs. The publication of a recent high-quality reference assembly with gene-level annotations, together with whole-genome population-level sequencing data, has facilitated a number of studies modeling the fundamental evolutionary processes shaping the patterns and levels of genetic variation in aye-ayes. In this review, we survey these recent findings, highlighting new insights into the selective and demographic history of the species, as well as into genome-wide patterns of mutation and recombination as assessed from both pedigree-based and divergence-/polymorphism-based analyses.

Foraging is a fundamental aspect of the behavioural ecology of any species. Chimpanzees (Pan troglodytes) are generalist omnivores that inhabit a continuous range of forest environments. Accordingly, substantial differences in feeding ecology exist across chimpanzee sub-species and populations. Despite a persistent importance for the role of ripe fruit, chimpanzee diets typically include a large variety of food types. While considerable data exist on the foraging behaviour and diets of chimpanzees, these are typically limited to studies of single communities in distinct populations. Previous studies in the Budongo forest, Uganda, have focused on the Sonso community; less is known of the foraging behaviour of the neighbouring Waibira community. Here, we present detailed descriptive data on diet, activity, and food availability from this community. These were collected between October 2016 and June 2017 from focal observations of ten adult males and nine adult females, phenological monitoring of 168 chimpanzee food trees, and 4 ha of botanical plots. These chimpanzees generally conformed to the view of this species as a ripe fruit specialist, but were notably less frugivorous than other study communities and showed a considerable reliance on young leaves, in particular the leaves of Celtis mildbraedii, and on the seeds of Cynometra alexandrii during the dry season. Dietary diversity was similar to that of the neighbouring Sonso community, and our results support the idea that significant folivory is a general foraging strategy for Budongo Forest chimpanzees.

The evolution of human language remains a puzzle, with comparative approaches focusing on vocalizations, gestures, bimodal combinations, and, most recently, social interaction and turn-taking. The latter is characterized by cooperative, reciprocal exchanges of alternating short bursts of information among interactants. Some hallmarks of human conversational turn-taking have been found in other primate species, suggesting a possible specialization of great apes in gestural rather than vocal turn-taking. However, relatively little is known about the vocal turn-taking abilities of great apes. Here, we conducted a systematic, quantitative study on vocal exchanges of adult male chimpanzees (Pan troglodytes) living in a habituated community in the Loango National Park, Gabon. We focused on pant-hoots, the typical long-distance calls of chimpanzees, which have been argued to function in some contexts as question-and-answer-like exchanges, referred to as “inquiring pant-hoots” (IPHs), a term coined by Goodall (1986). We collected a comprehensive data set over a period of 16 months (January–May 2019; November 2019–November 2020) resulting in a total of 1747 pant-hoots of ten adult males. We analyzed the data with a special focus on general pant-hoot patterns, criteria for IPHs, social factors, and temporal organization. Overall, general calling frequency was highest in males with high social ranks, in larger parties, and during periods of increased fission and fusion. Twenty percent of calls qualified as IPHs and were positively correlated with smaller party size, higher fission–fusion rates, and the absence of close social partners. Temporal patterns were influenced by social bond strength, the presence of drumming, and an avoidance of overlap. Our findings add to the growing evidence of complex vocal turn-taking abilities in nonhuman primates, contradicting the notion of a specialization in gestural rather than vocal turn-taking for chimpanzees and possibly other great apes. They also emphasize the role of long-distance vocalizations for species in fission–fusion societies and visually dense environments.

Captive primates maintained at accredited institutions can live extraordinarily long lives and, as a result, are useful models for understanding the physiology of aging. Many institutions monitor primate health using serum chemistry panels and complete blood counts (CBCs), assays that capture organ and immune function and provide rich data for retrospective research. In this study, we compiled results from 169 serum chemistry panels and 168 CBCs collected between 2011 and 2022 at the Duke Lemur Center from 60 ring-tailed lemurs (Lemur catta), aged between 9 months and 32.8 years. Our dataset included 20 individuals who were 15 years or older, 10 of whom were 20 years or older. We found patterns consistent with gradual, age-related change in biomarkers associated with pancreas, kidney, and hepatobiliary function. Whereas concentrations of some markers increased with increasing age (e.g., amylase, lipase, gamma-glutamyl transferase, globulin, and total CO₂), concentrations of others decreased with increasing age (e.g., total bilirubin, calcium, and anion gap). We found significant age-by-sex interaction effects on blood urea nitrogen and cholesterol values, with females exhibiting sharper age-related increases in these analytes, particularly in late age, that could indicate steeper declines in kidney function than those experienced by males. Ultimately, our results capture a portrait of senescence in captive ring-tailed lemurs with extended longevity, with implications for the management of geriatric lemurs under human care. More broadly, including lemurs with diverse social systems and ecologies in retrospective studies of aging could illuminate physiological trends deeply rooted in the primate family tree and those uniquely shaped by evolution in Madagascar.