The rhesus macaque (Macaca mulatta) is the most widely distributed nonhuman primate species, and captive populations play an important role in biomedical research due to close phylogenetic and physiological similarity to human beings. However, to our best knowledge, the spondyloarthritis (SpA) in rhesus macaques has been exclusively reported in captive or semicaptive populations rather than wild counterparts. In the present study, we report 2 cases of SpA observed in Taihangshan macaques (Macaca mulatta tcheliensis) inhabiting the Taihangshan Macaque National Nature Reserve, Henan Province, China. Among these 2 cases, one can be diagnosed as ankylosing spondylitis (AS) following accepted medical criteria, and another case showed evident fusion at the pubic symphysis which could be specific to rhesus macaque AS. We discuss the potential causes leading directly or indirectly to the development of SpA.

Rhesus macaque (Macaca mulatta), the iconic species of genus Macaca, is characterized by the greatest geographical distribution of all nonhuman primates and is an important resource in many wildlife-related tourism areas, especially in China. In the current study, the genetic diversity was assessed by ten microsatellite loci with DNA obtained from muscle tissue of deceased individuals of free-ranging but tourist-habituated rhesus population naturally inhabiting the Wulongkou Scenic Area, Jiyuan, China, where they have been exploited for tourism since the early 1980s. The results showed that the genetic diversity for the studied rhesus population was relatively lower compared with its wild and captive counterparts, and the samples collected from the population subdivision in the studied area could mask the finding. Therefore, we proposed that a group-based study of the genetic diversity would help to clarify the genetic structure/diversity of rhesus macaques in this area, and then reasonable management recommendations could be provided for the sustainable development of local wildlife-dominated tourism.

Alpha male replacement occurs in many group-living non-human primates, but its characteristics remain under-explored. Species of the genus Macaca live in multi-male, multi-female groups and are structured into four levels of social styles, which may impact alpha male replacement. Rhesus monkeys (Macaca mulatta) are classified as Grade 1, yet little is known about alpha male replacements in this species. This study investigated the occurrence and characteristics of alpha male replacements in rhesus monkeys inhabiting the southern end of Taihang Mountains, China. The types of alpha male replacements included succession (8/11), Rank Reversal (1/11), and Group Fission (2/11). The average age at which adult males took the alpha rank was 10.2 (±4.1, n = 11) years of age. Their average social rank prior to attaining alpha rank was 3.91 (±3.05, n = 11). The average tenure of alpha males after 2017 was 2.6 (±1.4, n = 5) years, which appeared shorter than that before 2017 (>7.5 ± 2.9 years, n = 4). The occurrence of alpha male replacements did not significantly correlate with group sizes, natality, the ratio of adult males to adult females, or the proportion of immatures. Compared with tolerant Macaca species, alpha male replacement in rhesus monkeys tend to be biased toward Succession, a pattern that may be linked to their extremely despotic social style. This study suggests that social style could interact with changes in social structure, deepening our understanding of the evolution of primate social systems.