Red-shanked doucs (Pygathrix nemaeus) are endangered, foregut-fermenting colobine primates which are difficult to maintain in captivity. There are critical gaps in our understanding of their natural lifestyle, including dietary habits such as consumption of leaves, unripe fruit, flowers, seeds, and other plant parts. There is also a lack of understanding of enteric adaptations, including their unique microflora. To address these knowledge gaps, we used the douc as a model to study relationships between gastrointestinal microbial community structure and lifestyle. We analyzed published fecal samples as well as detailed dietary history from doucs with four distinct lifestyles (wild, semi-wild, semi-captive, and captive) and determined gastrointestinal bacterial microbiome composition using 16S rRNA sequencing. A clear gradient of microbiome composition was revealed along an axis of natural lifestyle disruption, including significant associations with diet, biodiversity, and microbial function. We also identified potential microbial biomarkers of douc dysbiosis, including Bacteroides and Prevotella, which may be related to health. Our results suggest a gradient-like shift in captivity causes an attendant shift to severe gut dysbiosis, thereby resulting in gastrointestinal issues.

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Dental microwear is of special interest for two reasons. First, it has been proposed that specific dental microwear patterns are associated with specific diets and therefore that the diets of extinct forms may be deduced by analysis of microwear. Second, it has been suggested that the geometry of wear striations indicates the direction of masticatory movement. We tested these ideas by analyzing microwear of laboratory animals fed different diets. Twelve American opossums (Didelphis marsupialis) were fed soft cat food for 90 days. Two control animals were fed only this base diet, five animals had plant fiber added to their diet, four animals had chitin added to their diet, and one animal had fine ground pumice added to its diet (for the last 30 days of the feeding period). We examined the wear surface below the paracristid on the Ms and M, of each animal by SEM. No microwear pattern differences were observed on the plant fiber-fed, chitin-fed, or control animal's molars. The pumice-fed opossum had a distinct microwear pattern with many parallel striations, resembling those foundon the teeth of grass-eating hyraxes (Walker et al., 1978). These results suggest that 1) exogenous grit (this study) or plant parts containing opaline phytoliths (Walker et al., 1978) produce similar microwear patterns, and 2) the diets of extinct forms cannot always be deduced by the analysis of dental microwear. The absence of fine parallel striations on teeth of Siuapithecus examined by us suggests that grass parts were not an important part of its diet and that it avoided dietary fine grit. Furthermore, we found striations on opossum molars with deep, broad heads and shallow, narrow tails oriented in opposite directions on the the same Phase I wear facet. This suggests that the geometry of striations on Phase I wear facets does not allow one to determine the direction of masticatory movement.Recent interest has focused on the use of scanning electron microscopy (SEM) to study dental wear in primates and other mammals. Evidence of microwear patterns has been advanced to support hypotheses about dietary pattern and/or differential tooth use, as well as to make inferences about jaw movements during mastication and other oral activities. If microwear distinctions can be recognized and firmly established for many sorts of diets and oral activity patterns, this method of analysis would provide an important adjunct for determining the oral behavior of extinct primates. At present, we can make reliable generalizations about these behaviors in fossil primates only based on the structure of their teeth by analogy with those of living species with known oral behavior. Similarly, if it can be established that the conformation of wear is indicative of the direction of movements during tooth-tooth contacts this would be an

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