Animals exhibit consistent individual differences in their movement: a case study on location trajectories of Japanese macaques

Researching individual recognition (IR) is essential to understand the life history and adaptive behavior of social animals. Investigation of possible IR clues may also help us build new hypotheses about how social animals distinguish between different individuals. This study investigates behavioral individuality in Japanese macaques (Macaca fuscata), focusing on one specific trait that is movement. Using a recently developed tracking system based on Bluetooth® Low Energy beacons, we collected three-dimensional (3D) location data from five Japanese macaques living in a group cage. A non-parametric, neural network-based analysis of the data revealed the existence of consistent individual differences in extremely limited aspects of the movement data (2-min trajectory of 3D location). Our results support the validity of multimodal approaches in studying IR, beyond the typical single-frame face recognition method, both for researchers and animal agents

Stomach and colonic microbiome of wild Japanese macaques

Within the gastrointestinal tract, the physiochemical microenvironments are highly diversified among the different stages of food digestion. Accordingly, gut microbiome composition and function vary at different gut sites. In this study, we examine and compare the compositional and functional potential between the stomach and colonic microbiome of wild Japanese macaques (Macaca fuscata yakui) living in the evergreen forest of Yakushima Island. We find a significantly lower microbial diversity in the stomach than in the colon, possibly due to the stomach's acidic and aerobic environment, which is suboptimal for microbial survival. According to past studies, the microbial taxa enriched in the stomach are aero- and acid-tolerant. By functional prediction through PICRUSt2, we reveal that the stomach microbiome is more enriched in pathways relating to the metabolism of simple sugars. On the contrary, the colonic microbiota is more enriched with fiber-degrading microbes, such as those from Lachnospiracea, Ruminococcaceae, and Prevotella. Our study shows a clear difference in the microbiome between the stomach and colon of Japanese macaques in both composition and function. This study provides a preliminary look at the alpha diversity and taxonomic composition within the stomach microbiome of Japanese macaques, a hindgut-fermenting nonhuman primate

Phylogeographic history of Japanese macaques

[Aim] Understanding patterns and processes of geographic genetic variation within and among closely related species is the essence of phylogeography. Japanese macaques, also called snow monkeys, have been extensively studied, particularly in the fields of sociobiology, ecology and experimental biology; however, our knowledge of their evolutionary history is relatively limited. In this study we aimed to elucidate the geographic patterns of genetic variation in Japanese macaques and the processes that underlie them. [Location] Japan. [Taxa] Japanese macaque, Macaca fuscata; rhesus macaque, M. mulatta; Taiwanese macaque, M. cyclopis. [Methods] Double-digest restriction site-associated DNA (RAD) sequencing was used to identify genome-wide single nucleotide variants. We used fineRADstructure, ADMIXTURE and principal component analyses to estimate the genetic population structure. Phylogenetic relationships were then inferred based on neighbour-net, neighbour-joining, maximum likelihood and SVDquartets algorithms. We assessed gene flow using demographic inference and ABBA-BABA tests, and estimated past distributions during the Last Glacial Maximum (LGM) using ecological niche modelling. [Results] Japanese macaques show a sister group relationship with a clade comprising Chinese rhesus, Indian rhesus and Taiwanese macaques. Japanese macaques comprise major north-eastern and south-western clades, with a boundary located near central Japan, and gene flow between the north-eastern and south-western lineages was detected. Refugia during the LGM were estimated to be distributed in limited areas along the south coasts of the Japanese archipelago. [Main conclusions] Phylogeographic variation of Japanese macaques is likely due mainly to northeast–southwest divergence, which resulted from withdrawal into refugia during the glacial period, and subsequent gene flow

Phylogeographic history of Japanese macaques

[Aim] Understanding patterns and processes of geographic genetic variation within and among closely related species is the essence of phylogeography. Japanese macaques, also called snow monkeys, have been extensively studied, particularly in the fields of sociobiology, ecology and experimental biology; however, our knowledge of their evolutionary history is relatively limited. In this study we aimed to elucidate the geographic patterns of genetic variation in Japanese macaques and the processes that underlie them. [Location] Japan. [Taxa] Japanese macaque, Macaca fuscata; rhesus macaque, M. mulatta; Taiwanese macaque, M. cyclopis. [Methods] Double-digest restriction site-associated DNA (RAD) sequencing was used to identify genome-wide single nucleotide variants. We used fineRADstructure, ADMIXTURE and principal component analyses to estimate the genetic population structure. Phylogenetic relationships were then inferred based on neighbour-net, neighbour-joining, maximum likelihood and SVDquartets algorithms. We assessed gene flow using demographic inference and ABBA-BABA tests, and estimated past distributions during the Last Glacial Maximum (LGM) using ecological niche modelling. [Results] Japanese macaques show a sister group relationship with a clade comprising Chinese rhesus, Indian rhesus and Taiwanese macaques. Japanese macaques comprise major north-eastern and south-western clades, with a boundary located near central Japan, and gene flow between the north-eastern and south-western lineages was detected. Refugia during the LGM were estimated to be distributed in limited areas along the south coasts of the Japanese archipelago. [Main conclusions] Phylogeographic variation of Japanese macaques is likely due mainly to northeast–southwest divergence, which resulted from withdrawal into refugia during the glacial period, and subsequent gene flow

Hypercholesterolemia induced by spontaneous oligogenic mutations in rhesus macaques (Macaca mulatta)

[Background] A rhesus macaque with the fourth highest plasma cholesterol (CH) levels of 501 breeding macaques was identified 22 years ago. Seven offspring with gene mutations causing hypercholesterolemia were obtained. [Methods] Activity of low-density lipoprotein receptor (LDLR), plasma CH levels and mRNA expression levels of LDLR were measured after administration of 0.1% (0.27 mg/kcal) or 0.3% CH. [Results] Activity of p. (Cys82Tyr) of LDLR was 71% and 42% in the heterozygotes and a homozygote, respectively. The mRNA expression level of LDLR in the p. (Val241Ile) of membrane-bound transcription factor protease, site 2 (MBTPS2, S2P protein) was 0.83 times lower than normal levels. LDLR mRNA levels were increased for up to 4 weeks by administration of 0.3% CH before suddenly decreasing to 80% of the baseline levels after 6 weeks. [Conclusion] Oligogenic mutations of p. (Cys82Tyr) in LDLR and p. (Val241Ile) in MBTPS2 (S2P) caused hypercholesterolemia exceeding cardiovascular risk levels under a 0.1% CH diet