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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Colobines are similar in their exploitation of a high percentage of leaf matter. However, this observation obfuscates interesting differences among genera of Southeast Asian colobines in morphology and behavior that may be reflected in the degree to which they rely on mastication or gut volume and gut retention time when ingesting and digesting leaves. We detail the use of a laboratory-based method to measure the mechanical properties of foods selected and processed by 4 captive species of Southeast Asian Colobinae -Pygathrix nemaeus, Pygathrix cinerea, Trachypithecus delacouri, and Trachypithecus laotum hatinhensis-at the Endangered Primate Rescue Center (EPRC), Vietnam. We also detail a field method that quantifies chewing rates and chewing behavior via a consumer-grade video camera and laptop computer. Observations in the captive setting permit a degree of experimental control that is not possible in the wild, and the location of the EPRC in the primates' habitat country permitted us to provide leaves that they encounter and eat in the wild. We collected toughness data with a portable tester designed by Lucas et al. The average toughness of selected leaves does not differ among the taxa, nor does the length of time spent chewing foods. However, there are differences in feeding rate, with Trachypithecus spp. chewing foods twice as fast as Pygathrix spp. Our findings suggest that Trachypithecus spp. emphasize comminution of food by mastication, while Pygathrix spp. emphasize the comminution of leaf matter Int J Primatol (in the stomach. The hypothesis is supported by data on molar size, gut mass, and gut morphology. We provide new insights into dietary variation among primate species and detail methods that are typically conducted only in a laboratory setting. We augment the findings with additional data on activity, feeding rates, and tooth morphology.

Recently we noted the effects of experimental diets on microscopic dental wear in the American opossum and concluded that it might prove difficult to distinguish the microwear produced by an insectivorous diet from that produced by some kinds of herbivorous ones. We also noted that wear caused by gritty diets and those containing plant opal, although they might be confused with one another, are easily distinguished from other sorts of dietary wear. Our conclusions have been challenged on the basis that possibly we did not allow sufficient time in the experiments for diagnostic wear patterns to emerge. Additional data reported here show that this is not so. Even in our "control" animals, fed a relatively soft unabrasive diet, enough time elapsed to produce significant dental wear. A new technique is described which for the first time allows the study of changing patterns of microscopic wear in a living animal over a period of time, thus allowing each animal to serve as its own control. A solution containing a broad-spectrum proteolytic enzyme when applied to the teeth of an anesthetized animal removes the proteinaceous coat (pellicle) which will otherwise obscure wear scratches. Precision dental impressions can then be made which reveal the details of the pattern of microwear on the teeth.

Recent studies at the Endangered Primate Rescue Center (EPRC) in the Socialist Republic of Vietnam's Cuc Phuong National Park by Byron et al. ([2002] Am. J. Phys. Anthropol. [Suppl.] 34:51) and Covert and Byron ([2002] Caring for Primates) revealed unexpected locomotor and postural behaviors in the red-shanked douc langur (Pygathrix nemaeus). This paper further elucidates the question of red-shanked douc suspensory behavior, and provides initial positional behavior data for two other rare Asian colobines, by comparing the ontogenetic positional behavior of red-shanked douc langurs, Delacour's langurs (Trachypithecus delacouri), and Hatinh langurs (Trachypithecus hatinhensis) at the EPRC. Two hundred and seven hours of positional behavior data were collected, with approximately equal amounts of data on each species, and equal amounts on adults and those less than 18 months in age. All young animals were more active than adults, used a wider repertoire of locomotor behaviors, and expressed suspensory behaviors more frequently than did the adults. Young animals also "invented" one new locomotor and two new postural behaviors. These differences are due to both play and explorative behavior, as well as to the youths' changing musculoskeletal systems. The number of positional behaviors utilized by the adults of these species is quite similar to one another (23-32), as is that utilized by the young (51-56). Douc langurs in both age categories used suspensory behaviors more frequently than did Delacour's and Hatinh langurs. Because the uniformity of enclosures offers a control, the results of this study generate hypotheses regarding adaptive radiations and niche partitioning in wild populations.