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Gut bacteria may coexist with other groups of organisms, such as nematode parasites, that inhabit the gastrointestinal tract of primates; however, the possible effects of endoparasites on bacterial communities are frequently overlooked. Here we explored whether infection with Trypanoxyuris, an oxyurid gastrointestinal parasite, is associated with changes in the gut bacterial community of wild black howler monkeys (Alouatta pigra), by comparing gut bacterial communities of consistently infected individuals and individuals that never tested positive for Trypanoxyuris throughout different months across the year. We additionally controlled for other sources of variation reported to influence the primate microbiome including individual identity, social group, and seasonality. Trypanoxyuris infection was not related to differences in gut bacterial alpha diversity, but was weakly associated with differences in gut bacterial community structure. In contrast, among the covariates considered, both individual identity and social group were more strongly associated with variation in the howler gut bacterial community. Our results suggest that gastrointestinal parasites may be associated, to some extent, with shifts in the gut bacterial communities hosted by free‐ranging primates, although a causal link still needs to be established. Further studies of wild primate hosts infected with parasite species with different pathogenicity are needed to better elucidate health‐related consequences from the parasite‐microbiome interplay. Research highlights: 1.Pinworm (Trypanoxyuris) infection was associated with slight shifts in the gut bacterial community of black howler monkeys.2.The individual ID and social group played a stronger role shaping bacterial communities in this Alouatta pigra population.3.Bacterial taxa associated with colonic inflammation were increased in parasite‐infected individuals. [ABSTRACT FROM AUTHOR]

ABSTRACT In all mammals, growth, development, pregnancy, and lactation increase nutritional demands. Although primate field studies tend to focus on shifts in activity and diet as mechanisms to compensate for these demands, differences in digestive efficiency also are likely to be important. Because the gut microbiota can impact host digestive efficiency, we examined differences in activity budget, diet, and the gut microbial community among adult male ( N = 4), adult female ( N = 4), and juvenile ( N = 5) wild black howler monkeys ( Alouatta pigra) across a ten-month period in Palenque National Park, Mexico to determine how adult females and juveniles compensate for increased nutritional demands. Results indicate that adult females and juveniles consumed more protein and energy than adult males. Adult males, adult females, and juveniles also possessed distinct gut microbial communities, unrelated to diet. Juveniles exhibited a gut microbiota characterized by bacteria from the phylum Firmicutes, such as Roseburia and Ruminococcus, and demonstrated high fecal volatile fatty acid content, suggesting increased microbial contributions to host energy balances. Adult females possessed a higher Firmicutes to Bacteroidetes ratio, also suggesting increased energy production, and their gut microbiota was characterized by Lactococcus, which has been associated with folate biosynthesis. On the basis of these patterns, it appears that the gut microbiota differentially contributes to howler monkey nutrition during reproduction and growth. Determining the nutritional and energetic importance of shifts in activity, diet, and the gut microbiota in other nonhuman primate taxa, as well as humans, will transform our understanding of these life history processes and the role of host-microbe relationships in primate evolution. Am J Phys Anthropol 155:652-664, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Food resources consumed by primates vary markedly in nutritional content. As a result, foragers must develop a feeding strategy to select resources that balance energy and macronutrient intake and reduce the consumption of fiber and toxins. In this study, we collected data on dietary patterns, rates of food consumption, and weight of food items consumed and combined them with published values of the nutritional content of Neotropical foods to estimate energy and nutrient intake during a 10-month period in two groups ( N = 16 individuals) of black howler monkeys ( Alouatta pigra) inhabiting Palenque National Park, Mexico. Although howler monkeys are generally assumed to exploit a leaf-dominated diet and be energy-limited, our results indicated that black howlers met their estimated energy requirements, consuming an average of 0.58 MJ of overall energy per metabolic body mass per day. The howlers also surpassed protein requirements by consuming an average of 8.2 g of protein per metabolic body mass per day. The amount of time they spent resting was not correlated with the amount of leaves or fruit in the diet or with overall energy intake. Therefore, despite consuming a leaf-heavy diet during some months of the year, black howlers do not appear to be energy-limited. Additionally, the howlers maintained a relatively consistent level of average daily protein energy intake regardless of diet composition, while non-protein energy intake varied in response to the amount of ripe fruits consumed. Although our use of published nutritional data introduces error, these findings suggest that black howler feeding ecology is more similar to other fruit-eating atelines than previously suspected, and several common assumptions regarding howler behavior and feeding ecology need to be reexamined. Am. J. Primatol. 76:774-787, 2014. © 2014 Wiley Periodicals, Inc. [ABSTRACT FROM AUTHOR]

Intestinal methanogenesis is one of the major pathways for consumption of hydrogen produced by bacterial fermentation and is considered to affect the efficiency of host energy harvest; however, little information is available regarding the hydrogenotrophic pathways of nonhuman primates in the wild, in general, and of howler monkeys, in particular. Microbial fermentation of plant structural carbohydrates is an important feature in wild howlers owing to the high fiber and low available energy content of leaves, which make up the primary component of their diet. In contrast, captive howlers may consume greater quantities of fruits and vegetables that are higher in water, lower in fiber, and, along with commercial monkey chow commonly added to captive monkey diets, more readily digestible than the natural diet. In this study, we analyzed the composition of methanogens and sulfate-reducing bacteria (SRB) from fecal samples of black howler monkeys (Alouatta pigra) in the wild and in captivity. The hydrogenotrophic microbiota of three groups of monkeys was evaluated by PCR-denaturing gradient gel electrophoresis (DGGE) fingerprinting, small clone library construction, and quantitative real-time PCR. Abundance of methanogens was lower than SRB in all howler monkey groups studied. DGGE banding patterns were highly similar within each wild and captive group but distinct among groups. Desulfovibrionales-enriched DGGE showed reduced microbial diversity in the captive animals compared with their wild counterparts. Taken together, the data demonstrate that environmental or dietary changes of the host imposed by captivity likely influence the composition of intestinal hydrogenotrophs in black howler monkeys. [ABSTRACT FROM AUTHOR]

For most mammals, including nonhuman primates, diet composition varies temporally in response to differences in food availability. Because diet influences gut microbiota composition, it is likely that the gut microbiota of wild mammals varies in response to seasonal changes in feeding patterns. Such variation may affect host digestive efficiency and, ultimately, host nutrition. In this study, we investigate the temporal variation in diet and gut microbiota composition and function in two groups (N = 13 individuals) of wild Mexican black howler monkeys (Alouatta pigra) over a 10-month period in Palenque National Park, Mexico. Temporal changes in the relative abundances of individual bacterial taxa were strongly correlated with changes in host diet. For example, the relative abundance of Ruminococcaceae was highest during periods when energy intake was lowest, and the relative abundance of Butyricicoccus was highest when young leaves and unripe fruit accounted for 68 % of the diet. Additionally, the howlers exhibited increased microbial production of energy during periods of reduced energy intake from food sources. Because we observed few changes in howler activity and ranging patterns during the course of our study, we propose that shifts in the composition and activity of the gut microbiota provided additional energy and nutrients to compensate for changes in diet. Energy and nutrient production by the gut microbiota appears to provide an effective buffer against seasonal fluctuations in energy and nutrient intake for these primates and is likely to have a similar function in other mammal species.

We used data collected during two concurrent studies of black howler monkeys (Alouatta pigra) in Palenque National Park, Mexico, to compare systematically three methods of behavioral data collection [group activity scan sampling (group scans), instantaneous focal individual sampling (instantaneous focals) and continuous focal individual sampling (continuous focals)] and three methods of proximity data collection [group proximity scan sampling (group proximity scans), focal individual proximity scan sampling (focal proximity scans) and instantaneous focal individual nearest neighbor sampling (focal nearest neighbor samples)]. We conducted pairwise comparisons of data among methods using Pearson correlations and one-sample t tests. A series of Kruskal-Wallis tests were performed to compare the activity and proximity patterns of adult males, adult females and juveniles described by each method. The three behavioral data collection methods generally provided similar information about activity and diet. However, important differences for both activity and proximity data existed among methods. Instantaneous focals overestimated the percentage of time spent in social interactions, while group scans overestimated time spent moving and underestimated time spent feeding. Group proximity scans and focal proximity scans provided similar spatial data, while focal nearest neighbor samples were more appropriate for determining the influence of one individual on another at any given moment. These biases suggest the importance of deliberate method selection during project design and highlight the need for taking methods into account when comparing studies., (Copyright © 2013 S. Karger AG, Basel.)