Wancai Xia ¹ Zhongwei Lu ¹ Jiajie Zhou ¹ Liang Li ¹ Yuan Zhang ¹ Shiyuan Fan ¹ Ali Krzton ² Dayong Li ^1*

• ¹ Key Laboratory of Southwest China Wildlife Resources Conservation (Ministry of Education), China West Normal University, Nanchong City, China
• ² Auburn University Libraries, Auburn, United States

Background: Microplastics (MPs) has been rapidly increasing and interacting with wildlife. As the highest altitudes inhabited non-human primate, Yunnan snubnosed monkey (Rhinopithecus bieti) have been proven to be an umbrella and flagship species to indicate ecosystem changes and help develop environmental management strategies. In this study, we aimed to investigate the behavioral and ecological reasons for the types, content and differences of MPs in the feces of R. bieti, and explored the effects of MPs on gut microbiome of R. bieti.Methods: We used the Agilent 8700 LDIR to identify the abundance and size distribution of MPs in fecal samples, and then analyzed the causes of differences in MPs content by combining data from different populations (wild group, provisioned wild group) and dominance hierarchy. At the same times, the relationships were investigated between gut microbiome diversity and MPs content.We first demonstrate MPs ingestion by R. bieti, which highlights the potential impacts of MPs pollution in such high-altitude, inaccessible protected areas.A total of 36 types of MPs were detected, with an average of 75.263±58.141MPs/ g. The majority of MPs in the feces of R. bieti were characterized by a diameter of less than 100um, an area of 0-38000um, and a solidity of 0.8-1. Food provisioning and tourism significantly increased the content of MPs in the feces of R. bieti, but tourism alone did not significantly increase the content of MPs as food provisioning. At the same time, the study found that there was no significant difference in the content of MPs between different sex groups, however, the feces MPs content of adult R. bieti was significantly lower than that of juvenile, and the social dominance hierarchies among OMUs was positively correlated with the exposure of MPs. From the perspective of intestinal microbiology, it was proved that the current intake of MPs did not cause gut microbiome dysbiosis of R. bieti.Our study provided scientific basis for formulating effective protection measures and promoting the effective protection of rare and endangered animals.