Gastric acidity is likely a key factor shaping the diversity and composition of microbial communities found in the vertebrate gut. We conducted a systematic review to test the hypothesis that a key ...role of the vertebrate stomach is to maintain the gut microbial community by filtering out novel microbial taxa before they pass into the intestines. We propose that species feeding either on carrion or on organisms that are close phylogenetic relatives should require the most restrictive filter (measured as high stomach acidity) as protection from foreign microbes. Conversely, species feeding on a lower trophic level or on food that is distantly related to them (e.g. herbivores) should require the least restrictive filter, as the risk of pathogen exposure is lower. Comparisons of stomach acidity across trophic groups in mammal and bird taxa show that scavengers and carnivores have significantly higher stomach acidities compared to herbivores or carnivores feeding on phylogenetically distant prey such as insects or fish. In addition, we find when stomach acidity varies within species either naturally (with age) or in treatments such as bariatric surgery, the effects on gut bacterial pathogens and communities are in line with our hypothesis that the stomach acts as an ecological filter. Together these results highlight the importance of including measurements of gastric pH when investigating gut microbial dynamics within and across species.
Eating is a risky affair. All animals have to offset risks of feeding such as exposure to plant toxins, increased vulnerability to predation, or conspecific aggression with a food's energetic and ...nutritional return. What, when, and where an individual eats can impact fitness and, ultimately, species-level adaptations. Here, we explore the variables that influence primate feeding preference: food availability, chemical defense, and nutrient content. We present information demonstrating that consumers manipulate nutrient and energy intake, indicating that what may be a less-than-optimal food for one state of an animal's phenotype may not be for another. This evidence suggests that factors previously assumed to be constraints in Optimal Foraging Theory, Functional Response, and-recently-Fallback Food feeding models would be better categorized as variables. We conclude that "fallback" is not an intrinsic state of the food or the consumer and that this conclusion complicates the application of this concept to morphological features in the fossil record.
Animal-mediated seed dispersal is important for sustaining biological diversity in forest ecosystems, particularly in the tropics. Forest fragmentation, hunting, and selective logging modify forests ...in myriad ways and their effects on animal-mediated seed dispersal have been examined in many case studies. However, the overall effects of different types of human disturbance on animal-mediated seed dispersal are still unknown. We identified 35 articles that provided 83 comparisons of animal-mediated seed dispersal between disturbed and undisturbed forests; all comparisons except one were conducted in tropical or subtropical ecosystems. We assessed the effects of forest fragmentation, hunting, and selective logging on seed dispersal of fleshy-fruited tree species. We carried out a meta-analysis to test whether forest fragmentation, hunting, and selective logging affected 3 components of animal-mediated seed dispersal: frugivore visitation rate, number of seeds removed, and distance of seed dispersal. Forest fragmentation, hunting, and selective logging did not affect visitation rate and were marginally associated with a reduction in seed-dispersal distance. Hunting and selective logging, but not fragmentation, were associated with a large reduction in the number of seeds removed. Fewer seeds of large-seeded than of small-seeded tree species were removed in hunted or selectively logged forests. A plausible explanation for the consistently negative effects of hunting and selective logging on large-seeded plant species is that large frugivores, as the predominant seed dispersers for large-seeded plant species, are the first animals to be extirpated from hunted or logged forests. The reduction in forest area after fragmentation appeared to have weaker effects on frugivore communities and animal-mediated seed dispersal than hunting and selective logging. The differential effects of hunting and selective logging on large-and small-seeded tree species underpinned case studies that showed disrupted plant-frugivore interactions could trigger a homogenization of seed traits in tree communities in hunted or logged tropical forests. La dispersión de semillas por animales es importante para sustentar la diversidad biológica en ecosistemas forestales, particularmente en los trópicos. La fragmentación de bosques, la cacería y la tala selectiva modifican los bosques de muchas maneras y sus efectos sobre la dispersión de semillas por animales han sido examinados en muchos estudios de caso. Sin embargo, todavía se desconocen los efectos generales de los diferentes tipos de perturbación humana sobre la dispersión de semillas por animales. Identificamos 35 artículos que proporcionaron 83 comparaciones de dispersión de semillas por animales entre bosques perturbados y no perturbados; todas las comparaciones excepto una fueron en bosques tropicales o subtropicales. Evaluamos los efectos de la fragmentación del bosque, la cacería y la tala selectiva sobre la dispersión de especies de árboles con frutos carnosos. Efectuamos un meta análisis para probar si la fragmentación del bosque, la cacería y la tala selectiva afectaban a tres componentes de la dispersión de semillas por animales: tasa de visitación de frugívoros, números de semillas removidas y distancia de dispersión de semillas. La fragmentación del bosque, la cacería y la tala selectiva no afectaron la tasa de visitación y estuvieron marginalmente asociadas con la disminución de la distancia de dispersión. La cacería y la tala selectiva, pero no la fragmentación, se asociaron con una reducción importante en el número de semillas removidas. Menos semillas de especies de árboles con semillas grandes que de semillas pequeñas fueron removidas en bosques con cacería o tala selectiva. Una explicación plausible de los efectos consistentemente negativos de la cacería y la tala selectiva sobre las especies con semillas grandes es que los frugívoros grandes, como los dispersores predominantes de especies de plantas con semillas grandes, son los primeros animales extirpados de bosques con cacería o tala. La reducción de la superficie de bosque después de la fragmentación pareció tener efectos más débiles sobre las comunidades de frugívoros y la dispersión de semillas por animales que la cacería y la tala selectiva. Los efectos diferenciales de la cacería y la tala selectiva sobre especies de árboles con semillas grandes y pequeñas sustentaron estudios de caso que mostraron que la alteración de interacciones planta-frugívoro podría detonar la homogenización de atributos de las semillas en comunidades de árboles en bosques tropicales con cacería o tala.
In this research, we use a combination of ethnographic observation and GIS analysis to explore the use of space by humans and gibbons (Hylobates moloch) to determine areas of potential space ...competition in the sacred forest and nature reserve Cagar Alam Leuweung Sancang in West Java, Indonesia. More specifically, we test whether gibbons respond to the presence of humans in a manner consistent with predator-avoidance and predicted that the gibbon study subjects would avoid areas visited by humans (Risk-Disturbance Hypothesis). Data were collected August 2010-June 2011. We collected GPS locations and behavioral data on both the humans (6,652 hours) and the gibbons (1,253 hours) in the forest using 10 minute instantaneous sampling. Results indicate that humans preferentially assemble at the most sacred spot in the forest (Cikajayaan waterfall). Two gibbon groups' home ranges encompassed most of the sacred areas. Group B avoided areas of high human use, as high human use areas and high gibbon use areas did not overlap. Group C, though, continued to use areas that were heavily visited by humans. We thus found partial support for the Risk-Disturbance Hypothesis, although the variation in gibbon response to human disturbance indicates behavioral flexibility. We suggest that understanding the effects of shared space on wildlife is necessary for informing conservation policy in human-visited forests.
Exclusive frugivory is rare. As a food resource, fruit is temporally and spatially patchy, low in protein, and variable in terms of energy yield from different carbohydrate types. Here, we evaluate ...the digestive physiology of two frugivorous Carnivora species (Potos flavus, Arctictis binturong) that converge with primates in a diversity of ecological and anatomical traits related to fruit consumption. We conducted feeding trials to determine mean digestive retention times (MRT) on captive animals at the Carnivore Preservation Trust (now Carolina Tiger Rescue), Pittsboro, NC. Fecal samples were collected on study subjects for in vitro analysis to determine methane, pH, and short chain fatty acid profiles; fiber was assayed using standard neutral detergent (NDF) and acid detergent (ADF) fiber methods. Results indicate that both carnivoran species have rapid digestive passage for mammals that consume a predominantly plant-based diet: A. binturong MRT = 6.5 hrs (0.3); P. flavus MRT = 2.5 hrs (1.6). In vitro experiments revealed no fermentation of structural polysaccharides--methane levels did not shift from 0 h to either 24 or 48 hours and no short chain fatty acids were detected. In both species, however, pH declined from one incubation period to another suggesting acidification and bacterial activity of microbes using soluble carbohydrates. A comparison with primates indicates that the study species are most similar in digestive retention times to Ateles--the most frugivorous anthropoid primate taxon.
Human–wildlife interactions, including human–wildlife conflict, are increasingly common as expanding urbanization worldwide creates more opportunities for people to encounter wildlife. ...Wildlife–vehicle collisions, zoonotic disease transmission, property damage, and physical attacks to people or their pets have negative consequences for both people and wildlife, underscoring the need for comprehensive strategies that mitigate and prevent conflict altogether. Management techniques often aim to deter, relocate, or remove individual organisms, all of which may present a significant selective force in both urban and nonurban systems. Management‐induced selection may significantly affect the adaptive or nonadaptive evolutionary processes of urban populations, yet few studies explicate the links among conflict, wildlife management, and urban evolution. Moreover, the intensity of conflict management can vary considerably by taxon, public perception, policy, religious and cultural beliefs, and geographic region, which underscores the complexity of developing flexible tools to reduce conflict. Here, we present a cross‐disciplinary perspective that integrates human–wildlife conflict, wildlife management, and urban evolution to address how social–ecological processes drive wildlife adaptation in cities. We emphasize that variance in implemented management actions shapes the strength and rate of phenotypic and evolutionary change. We also consider how specific management strategies either promote genetic or plastic changes, and how leveraging those biological inferences could help optimize management actions while minimizing conflict. Investigating human–wildlife conflict as an evolutionary phenomenon may provide insights into how conflict arises and how management plays a critical role in shaping urban wildlife phenotypes.
Abstract
Background
Comparative data from non-human primates provide insight into the processes that shaped the evolution of the human gut microbiome and highlight microbiome traits that ...differentiate humans from other primates. Here, in an effort to improve our understanding of the human microbiome, we compare gut microbiome composition and functional potential in 14 populations of humans from ten nations and 18 species of wild, non-human primates.
Results
Contrary to expectations from host phylogenetics, we find that human gut microbiome composition and functional potential are more similar to those of cercopithecines, a subfamily of Old World monkey, particularly baboons, than to those of African apes. Additionally, our data reveal more inter-individual variation in gut microbiome functional potential within the human species than across other primate species, suggesting that the human gut microbiome may exhibit more plasticity in response to environmental variation compared to that of other primates.
Conclusions
Given similarities of ancestral human habitats and dietary strategies to those of baboons, these findings suggest that convergent ecologies shaped the gut microbiomes of both humans and cercopithecines, perhaps through environmental exposure to microbes, diet, and/or associated physiological adaptations. Increased inter-individual variation in the human microbiome may be associated with human dietary diversity or the ability of humans to inhabit novel environments. Overall, these findings show that diet, ecology, and physiological adaptations are more important than host-microbe co-diversification in shaping the human microbiome, providing a key foundation for comparative analyses of the role of the microbiome in human biology and health.
Nonhuman primates, our closest biological relatives, play important roles in the livelihoods, cultures, and religions of many societies and offer unique insights into human evolution, biology, ...behavior, and the threat of emerging diseases. They are an essential component of tropical biodiversity, contributing to forest regeneration and ecosystem health. Current information shows the existence of 504 species in 79 genera distributed in the Neotropics, mainland Africa, Madagascar, and Asia. Alarmingly, ~60% of primate species are now threatened with extinction and ~75% have declining populations. This situation is the result of escalating anthropogenic pressures on primates and their habitats-mainly global and local market demands, leading to extensive habitat loss through the expansion of industrial agriculture, large-scale cattle ranching, logging, oil and gas drilling, mining, dam building, and the construction of new road networks in primate range regions. Other important drivers are increased bushmeat hunting and the illegal trade of primates as pets and primate body parts, along with emerging threats, such as climate change and anthroponotic diseases. Often, these pressures act in synergy, exacerbating primate population declines. Given that primate range regions overlap extensively with a large, and rapidly growing, human population characterized by high levels of poverty, global attention is needed immediately to reverse the looming risk of primate extinctions and to attend to local human needs in sustainable ways. Raising global scientific and public awareness of the plight of the world's primates and the costs of their loss to ecosystem health and human society is imperative.
Insectivory, or the consumption of insects and other arthropods, is a significant yet cryptic component of omnivorous primate diets. Here, we used high-throughput DNA sequencing to identify ...arthropods from fecal DNA and assess variation in insectivory by closely-related sympatric primates. We identified arthropod prey taxa and tested the hypothesis that variation in insectivory facilitates niche differentiation and coexistence among closely-related species with high dietary overlap. We collected 233 fecal samples from redtail (Cercopithecus ascanius; n = 118) and blue monkeys (C. mitis; n = 115) and used a CO1 metabarcoding approach to identify arthropod DNA in each fecal sample. Arthropod DNA was detected in 99% of samples (N = 223 samples), and a total of 68 families (15 orders) were identified. Redtails consumed arthropods from 54 families, of which 12 (21.8%) were absent from blue monkey samples. Blue monkeys consumed arthropods from 56 families, of which 14 (24.6%) were absent from redtail samples. For both species, >97% of taxa present belonged to four orders (Araneae, Diptera, Hymenoptera, Lepidoptera). Redtail samples contained more Lepidoptera taxa (p<0.05), while blue monkey samples contained more Araneae (p<0.05). Blue monkeys consumed a greater diversity of arthropod taxa than redtail monkeys (p<0.05); however, the average number of arthropod families present per fecal sample was greater in the redtail monkey samples (p<0.05). These results indicate that while overlap exists in the arthropod portion of their diets, 20-25% of taxa consumed are unique to each group. Our findings suggest that variation in arthropod intake may help decrease dietary niche overlap and hence facilitate coexistence of closely-related primate species.
Objectives
Geophagy, the intentional consumption of earth, is widely practiced among humans and other mammals, but its causes are not well understood. Given the growing number of reports of geophagy ...among nonhuman primates (NHP), we sought to (1) advance and codify our understanding of the patterns and functional and evolutionary significance of geophagy among NHP and (2) provide a research agenda for a more unified approach to its study.
Methods
We systematically reviewed all available literature on NHP geophagy, extracted available data on taxa, geography, climate, diet, sex, age‐class, reproductive status, and the characteristics of the earth. We used these data to evaluate three major hypotheses about geophagy, that it is protective, provides mineral supplementation, and is nonadaptive.
Results
We identified 287 accounts of geophagy among 136 species, adding 79 new primate species to the list of those considered in prior reviews. Nineteen percent of species were in the suborder Strepsirrhini, while 81% were in the suborder Haplorrhini. There were reports of geophagy from 9 of the 17 families and 39 of the 76 genera currently recognized by the International Union for Conservation of Nature.
Discussion
The limited evidence suggests that geophagy is adaptive, and provides protection and mineral supplementation. We specify the behavioral, dietary, and soil data required to more rigorously investigate these hypotheses across representative species of all taxonomic groups, geographical regions, and dietary classification. Given the plausibility of geophagy for maintaining the health of both wild and captive populations, we urge further study and conservation of geophagy sites.
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