Vervet Research Articles

Preliminary evidence for one-trial social learning of vervet monkey alarm calling.

How do non-human primates learn to use their alarm calls? Social learning is a promising candidate, but its role in the acquisition of meaning and call usage has not been studied systematically, neither during ontogeny nor in adulthood. To investigate the role of social learning in alarm call comprehension and use, we exposed groups of wild vervet monkeys to two unfamiliar animal models in the presence or absence of conspecific alarm calls. To assess the learning outcome of these experiences, we then presented the models for a second time to the same monkeys, but now without additional alarm call information. In subjects previously exposed in conjunction with alarm calls, we found heightened predator inspection compared to control subjects exposed without alarm calls, indicating one-trial social learning of ‘meaning’. Moreover, some juveniles (but not adults) produced the same alarm calls they heard during the initial exposure whereas the authenticity of the models had an additional effect. Our experiment provides preliminary evidence that, in non-human primates, call meaning can be acquired by one-trail social learning but that subject age and core knowledge about predators additionally moderate the acquisition of novel call-referent associations.

Xenon-enhanced computed tomography assessment of brown adipose tissue distribution and perfusion in lean, obese, and diabetic primates.

ObjectiveThis study aimed to validate xenon‐enhanced computed tomography (XECT) for the detection of brown adipose tissue (BAT) and to use XECT to assess differences in BAT distribution and perfusion between lean, obese, and diabetic nonhuman primates (NHPs).MethodsWhole‐body XECT imaging was performed in anesthetized rhesus and vervet monkeys during adrenergic stimulation of BAT thermogenesis. In XECT images, BAT was identified as fat tissue that, during xenon inhalation, underwent significant radiodensity enhancement compared with subcutaneous fat. To measure BAT blood flow, BAT radiodensity enhancement was measured over time on the six computed tomography scans acquired during xenon inhalation. Postmortem immunohistochemical staining was used to confirm imaging findings.ResultsXECT was able to correctly identify all BAT depots that were confirmed at necropsy, enabling construction of the first comprehensive anatomical map of BAT in NHPs. A significant decrease in BAT perfusion was found in diabetic animals compared with obese animals and healthy animals, as well as absence of axillary BAT and significant reduction of supraclavicular BAT in diabetic animals compared with obese and lean animals.ConclusionsThe use of XECT in NHP models of obesity and diabetes allows the analysis of the impact of metabolic status on BAT mass and perfusion.

Epigenetic Reprogramming Leads to Downregulation of CD4 and Functional Changes in African Green Monkey Memory CD4+ T Cells.

African green monkeys (AGMs), Chlorocebus pygerythrus, are a natural host for a lentivirus related to HIV, SIV. SIV-infected AGMs rarely progress to AIDS despite robust viral replication. Though multiple mechanisms are involved, a primary component is the animals' ability to downregulate CD4 expression on mature CD4+ Th cells, rendering these cells resistant to infection by SIV. These CD8αα+ T cells retain functional characteristics of CD4+ Th cells while simultaneously acquiring abilities of cytotoxic CD8αβ+ T cells. To determine mechanisms underlying functional differences between T cell subsets in AGMs, chromatin accessibility in purified populations was determined by assay for transposase-accessible chromatin sequencing. Differences in chromatin accessibility alone were sufficient to cluster cells by subtype, and accessibility at the CD4 locus reflected changes in CD4 expression. DNA methylation at the CD4 locus also correlated with inaccessible chromatin. By associating accessible regions with nearby genes, gene expression was found to correlate with accessibility changes. T cell and immune system activation pathways were identified when comparing regions that changed accessibility from CD4+ T cells to CD8αα+ T cells. Different transcription factor binding sites are revealed as chromatin accessibility changes, and these differences may elicit downstream changes in differentiation. This comprehensive description of the epigenetic landscape of AGM T cells identified genes and pathways that could have translational value in therapeutic approaches recapitulating the protective effects CD4 downregulation.

Role of immigrant males and muzzle contacts in the uptake of a novel food by wild vervet monkeys

Role of immigrant males and muzzle contacts in the uptake of a novel food by wild vervet monkeys

Using network synchrony to identify drivers of social dynamics.

Social animals frequently show dynamic social network patterns, the consequences of which are felt at the individual and group level. It is often difficult, however, to identify what drivers are responsible for changes in these networks. We suggest that patterns of network synchronization across multiple social groups can be used to better understand the relative contributions of extrinsic and intrinsic drivers. When groups are socially separated, but share similar physical environments, the extent to which network measures across multiple groups covary (i.e. network synchrony) can provide an estimate of the relative roles of extrinsic and intrinsic drivers. As a case example, we use allogrooming data from three adjacent vervet monkey groups to generate dynamic social networks. We found that network strength was strongly synchronized across the three groups, pointing to shared extrinsic environmental conditions as the driver. We also found low to moderate levels of synchrony in network modularity, suggesting that intrinsic social processes may be more important in driving changes in subgroup formation in this population. We conclude that patterns of network synchronization can help guide future research in identifying the proximate mechanisms behind observed social dynamics in animal groups.

Canopy bridges are an economical mitigation reducing the road barrier effect for three of four species of monkeys in Diani, Kenya

Abstract For primates, canopy bridges can reduce the road barrier effect. Yet little information exists to predict species bridge use. We examined bridge use across a 9 km suburban road in Diani, Kenya, in three survey years (Nbridges: 21 = 2004, 27 = 2011, 29 = 2020) by four sympatric species of monkeys. The asphalt road is 6 m wide with a 50 km/h speed limit. Roadside observers recorded ground () and bridge () crossings, crossing direction, and traffic volume. Colobus (Colobus angolensis palliatus), Sykes’ monkeys (Cercopithecus mitis albogularis), and vervets (Chlorocebus pygerythrus hilgerti) used the bridges while baboons (Papio cynocephalus cynocephalus) rarely did. Crossing rates (Sykes’>vervet>colobus>baboon) did not fit our predictions based on species’ attributes of stratum preference (arboreal>terrestrial) or body mass (small>large), while the interaction between these attributes was more informative. Crossings were bidirectional. Colobus crossed bridges during higher traffic volumes than on the ground, whereas we found the opposite for vervets. Sykes’ monkeys crossed at similar traffic volumes on the ground and bridges. The mean annual bridge cost was USD 157, deriving a cost per crossing as < USD 0.10, though it undervalues the savings in ecosystem services, tourism benefits, and contributions to protecting colobus, a vulnerable species. While we consider this highly economical, funders and road engineers will ultimately determine if it is so.

Impact of linear infrastructure on South Africa’s primate fauna: the need for mitigation

Abstract South Africa’s extensive linear infrastructure network (which includes roads and power lines) is severely impacting the country’s historically recognised five primate species: greater or thick-tailed bushbaby (Otolemur crassicaudatus), southern lesser bushbaby (Galago moholi), chacma baboon (Papio ursinus), vervet monkey (Chlorocebus pygerythrus) and samango monkey (Cercopithecus albogularis). We present South African mortality data from two different linear infrastructure types on a country wide scale, over a long-term sampling period. Using primate road mortality and power line electrocution data acquired from different data sources, we compare and discuss different mortality data collection methodologies, the resulting data quality and identify current limitations in understanding the direct impacts of linear infrastructure which have important implications for primate conservation planning. Between 1996-2021 a total of 483 primate mortalities were recorded on roads and power lines, the majority on the former. Vervet monkeys were most severely impacted by both linear infrastructure types whereas lesser bushbabies experienced the least number of mortalities. Both data sets showed numerous incidents where more than one individual was killed (roadkill: 4%, up to four killed in one incident; electrocutions: 13%, up to six killed in one incident). GPS coordinates were available for 61% of roadkill records and for 65% of electrocution records. Age or sex of carcasses were not available for electrocution records and only available for 11% of roadkill records. Although South Africa leads the African continent regarding roadkill and electrocution data collection, there are still areas in the collection protocol that can be improved and projects implementing mitigation measures (e.g. canopy bridges) to reduce primate roadkill are lacking. We argue that the mortality data presented here should form the basis for future mitigation implementation and recommend that linear infrastructure be more prominently recognised as a direct threat when developing national and international Red Lists.

Diversity, Abundance, and Habitat Association of Medium and Large-Sized Mammals in Tiski Waterfall, Awi Zone, Ethiopia

The reliable data on faunal diversity, abundance, and habitat preference are essential for proposing and establishing relevant conservation interventions. A survey was done from September 2019 to March 2021 to investigate the diversity, relative abundance, and habitat association of large and medium mammals in Tiski Waterfall, Ethiopia. Data were collected using the line transect survey method in both habitat types. In cliff sites, the point transect was also used. The habitats were populated by large and medium animal species that favor dense forest and shrubland habitats near water sources. During the research, three different habitat categories were evaluated (dense forest, shrubland, and cliff sites). Ten mammalian species were discovered. During the wet season, there were 243 ± 6.6 populations recorded, while during the dry season, there were 204 ± 6.8. Seasonal differences in species abundance were statistically significant p ≤ 0. 001 . The total populations of the three habitat types were 198.2 ± 7.39, 135 ± 5.35, and 114 ± 5.16 for dense forest, shrubland, and cliff site, respectively. All three habitat categories had a great difference in species abundance p ≤ 0. 001 . The olive baboon (Papio anubis) was the most common, accounting for 38 percent of the population, followed by the vervet monkey (Cercopithecus aethiops), which accounted for 23 percent. Leopard (Panthera pardus) and common bushbuck (Tragelaphus scriptus) contributed the least to the total, accounting for only 2% each of the total. The highest diversity of mammalian species was found in dense forest (H′ = 0.98), followed by shrubland (H′ = 0.90), and the cliff location has the lowest diversity (H′ = 0.57). The maximum uniformity of the species was found in dense forests (J = 0.51), followed by a shrub region (J = 0.43), and the remaining of the habitat (J = 0.35). Dense forest and shrubland had the highest species similarity (Sl = 0.67), followed by shrubland and cliff site (SI = 0.61). In dense forests with cliff sites, the similarity was lowest (SI = 0.31) in each. To limit the impact of agricultural growth on big and medium mammals, good habitat management is required.

A Pilot Assessment of Inosine Effects on Blood Pressure in Vervet Monkeys

ObjectivesInosine, a purine metabolite, has been shown to have anti-inflammatory and cardioprotective effects. Studies in rodent models have shown conflicting effects of inosine on blood pressure, a key risk factor for cardiovascular disease (CVD). Vervet monkeys (Chlorocebus aethiops sabaeus) are genetically and physiologically similar to humans. Thus, they are excellent models to study CVD or related risk factors. Our aim in this pilot study was to determine the effects of inosine on blood pressure in in a cohort of 16 Vervet monkeys. MethodsEight monkeys (50% female) were randomly assigned to be orally gavaged 250 mg/kg of inosine (mixed in Ensure® nutrition shake) for 7 days while the other eight (50% female) were given just the nutrition shake (control). Anthropometric and biochemical measures were obtained at baseline, post-treatment (7 days) and post-wash out period (14 days). Blood pressure was measured using high definition Oscillometry at both time points. Statistical analysis was conducted using STATA (Stata/BE 17.0). ResultsAt baseline, males had higher body weight than females (7.86 ±1.1 vs. 5.95 ± 1.2 kg, p = 0.005) whereas blood pressure and waist circumference were not significantly different between them. There was a significant decrease in body weight in females (–0.26±0.05 kg, p < 0.02) in the treatment group as compared to males (0.14±0.06 kg) or females in the control group (0.16 ± 0.06 kg). Sex-specific changes in systolic blood pressure were also observed. Systolic blood pressure increased in control group as compared to the treatment group (20 ± 6.6 mmHg vs. 6.8 ±2.8 mmHg, p < 0.06, respectively) in males and (10.1 ± 5.5 mmHg vs. 1.3±17 mmHg, p = .16, respectively) in females. Similar results were found for mean arterial pressure. Changes in waist circumference or diastolic blood pressure were not significantly different either between sexes or treatment groups. ConclusionsResults of this pilot study are promising as inosine seems to have a stronger effect on body weight and systolic blood pressure as compared to the control group. However, more in-depth investigations are required to confirm and validate these initial findings. Funding SourcesA pilot grant from Nutrition Research Institute, University of North Carolina at Chapel Hill to VSV.

Can urbanization accentuate hand use in the foraging activities of primates?

How a species uses its anatomical manipulators is determined by its anatomy, physiology, and ecology. While ecology explains interspecific variation in gripping, grasping, and manipulating objects, its role in intraspecific variation in mouth- and hand-use by animals is less explored. Primates are distinguished by their prehensile capabilities and manual dexterity. In context to the adaptive pressures of urbanization on primates, we examined if mouth and hand use differed across the forest-urban gradient in food retrieval and processing under experimental and naturalistic conditions in cercopithecids, a family comprising several urbanizing primates. We recorded the acquisition and processing of peanuts under experimental conditions in three groups of bonnet macaques (BM, Macaca radiata) differing in their dietary dependence on packaged food items along a rural-urban gradient. To affirm the pattern obtained in the experiment, we coded food acquisition of three cercopithecid species in similar habitats from video sources. Urban macaques had a disproportionately higher hand use to acquire and process peanuts while rural macaques had higher mouth use. Based on analyses of videos, urban populations of BM, Japanese macaque (M. fuscata) and vervet monkey (Chlorocebus pygerythrus) showed a bias toward hand use during food acquisition. The adaptive pressures of urbanization, like the manual constraints of extracting packaged foods and perhaps, the need for visual-haptic exploration of novel objects seem to accentuate hand use in synanthropic groups of primates. Additional research should ascertain similar patterns in other primates and determine specific aspects of urbanization that modulate the observed trend.

Testing the Short-Term Effectiveness of Various Deterrents for Reducing Crop Foraging by Primates

Crop foraging by wildlife is a major driver of negative interactions between farmers and wildlife, and yet there are few published examples of effective solutions to deter wildlife from crops. Here we investigate the effectiveness of six different methods to deter primates from crop foraging on commercial farms in South Africa. Model snakes and bioacoustic sounds had no effect on chacma baboons (Papio ursinus). A leopard model and the sound of bees reduced the foraging duration at bait stations of vervet monkeys (Chlorocebus pygerythrus) and baboons, respectively. Human sounds appeared to reduce the number of days baboons visited a bait station, but not their foraging duration. Only an electric fence was effective at keeping both baboons and vervets out of a crop field. We encourage modifications to electric fence designs to avoid electrocution of smaller animals and make recommendations for other deterrent methods that require further investigation.

A Non‐Human Primate Model of Carfentanil Overdose: Preventing Renarcotization with Superior Countermeasures

We established a physiological and overt intoxication model using African green monkeys (Chlorocebus aethiops sabeus) and a high dose of injected carfentanil. Intoxication is rapid and rescue is typically required within 10 minutes. Naloxone, administered at a 10 mg human‐equivalent dose (HED; 0.355 mg/kg), is immediately effective but is limited by its short duration of action. Specifically, animals typically return to a state of severe respiratory depression within about 2.5 hours, necessitating further medical intervention. Therefore, we studied two novel medical countermeasures: nalmefene and CS‐1131. Nalmefene is a mu‐opioid antagonist with high affinity and a much longer duration of action, but little is known about its efficacy against carfentanil. Therefore, we covered a range of doses from 3‐30 mg estimated HED (based upon allometric scaling) through both the intramuscular and intranasal routes. CS‐1131 is a novel opioid scavenger (created by Clear Scientific, LLC) capable of binding carfentanil stoichiometrically, inactivating the synthetic opioid, and then eliminating the scavenger‐opioid complex through renal excretion. Results show that both countermeasures were superior to naloxone alone and exhibited dose‐dependent efficacy. This research provides strong proof‐of‐concept and sets the stage for additional studies of longer‐lasting opioid antagonists administered through various routes, and for the further development, characterization, and refinement of novel opioid scavenger molecules. This non‐human primate model can be utilized to study potent synthetic opioids, new analogues, and other novel countermeasures in a way that yields predictive results to support human clinical trials.

Sex Differences in Insulin Sensitivity and Glomerular Function in African Green Monkeys

In the United States, it is estimated that approximately 10.5% of the population has diabetes of which 90% are classified as insulin resistant expressing Type 2 Diabetes Mellitus (T2DM). T2DM is one of the leading causes of end stage renal disease (ESRD) accounting for approximately 40% of new ESRD cases. Previous studies have reported a more prevalent decrease in renal function in glucose intolerant males when compared to pre‐menopausal females. Males also have been reported to have earlier onset and higher prevalence of T2DM compared to pre‐menopausal females. Renal injury can be present before the onset of T2DM however, sex differences in renal injury have yet to be assessed in humans. A subpopulation of African Green Monkeys (AGM; Chlorocebus aethiops sabaeus) in the Caribbean exhibit spontaneous glucose intolerance and co‐morbidities such as insulin insensitivity, and hypertension. The AGM also shares similar genomic expression and metabolic phenotypes to humans making them optimal for translatable diabetes research. We hypothesize that female AGM are protected against renal injury and early onset T2DM. Systolic blood pressure (SBP) was measured by forearm plethysmography. Glucose tolerance was assessed via conscious and anesthetized oral glucose tolerance tests (OGTT). All AGM were fasted 12‐18 hours prior to study with water provided ad libitum. Blood glucose was measured at 0, 15, 30, 60, 90, and 120 min after an oral glucose load. Conscious AGM OGTT were delivered as 0.75g glucose/kg body weight. Sedated AGM (ketamine, 15mg/kg, i.m.), received 5g/dl glucose and 15 ml/kg in water by oral gavage. Venous blood samples were collected at timepoints 0, 30, 60, and 120 minutes post glucose administration. Urine samples were collected for 3 days post OGTT. Kidney histology was performed by staining 10µm sections with Periodic‐Acid Schiff stain (PAS). A minimum of 10 glomeruli were identified at 400x magnification per animal then analyzed with ImageJ. There were no differences between lightly sedated or conscious OGTT. All AGM in this study were normotensive and there were no sex differences in blood pressure between male and female AGM (F=11; 113.9±3.73 mmHg, M=6; 117.6 ± 6.3mmHg). Female AGM OGTT area under the curve (AUC) over 120 minutes post glucose load were lower compared to male AGM (F; 11,961.5± 710.6 min x mg/dl, M; 14,076.3±710.6 min x mg/dl, p&lt;0.05). There were no significant differences in plasma insulin at all time points between male and female AGM (F; 2,013± 1,007 min x mIU/L, M; 5,940± 1,424.6 min x mIU/L) despite the lower glucose AUC in females. Renal glomerular function was assessed by measuring plasma creatinine, urinary albumin, and urinary albumin to creatinine ratio (UACR). Plasma creatinine was not different between male and females (F; 1.35±0.2 mg/dl, M; 1.77±0.25 mg/dl). Microalbuminuria was present in both male and female AGMs, in the absence of sex differences (F; 98.43±23.1 ng/ml, M; 81.15±29.2 ng/ml). UACRs were not different between male and female AGM. Glomerular injury was assessed by determining the intensity of glomerular PAS stain. PAS stain intensity was not different in male and female AGM (F=3; 178.3 ± 8.6, M=3; 181.6± 8.6) regardless of OGTT sensitivity. Together these data suggest that female AGM are more insulin sensitive than male AGM and may be protected against early onset T2DM. Despite differences in OGTT in male and female AGM, microalbuminuria suggested onset of renal dysfunction. We conclude that the AGM provides a strong nonhuman primate model of T2DM for the long‐term study of sex differences in the mechanisms of ESRD.

Terrestrial medium and large-sized mammalian species diversity in Michole Community Protected Forest, southern Ethiopia

The study on medium and large-sized mammalian species' diversity and distribution is important for conservation efforts in the different protected areas of Ethiopia. The present study was intended to investigate the species diversity of medium and large-sized mammalian fauna between October 2019 and July 2020 in Michole Community Protected Forest, southern Ethiopia. The study was conducted by stratification of the study area into three habitat types: riverine forest (3.37 km2), woodland (4.14 km2), and grassland with scattered trees (2.33 km2) based on the vegetation cover. A diurnal transect survey method was implemented to record the mammalian species diversity. A total of 18 representative sample transect lines (six in riverine forest, four in grassland with scattered trees, and eight in woodland habitats) that varied in length and width were used. A total of 17 species of medium and large-sized mammalian species were identified and recorded in the study area. As a result, the orders Carnivora and Primates have the greatest abundance, while the order Lagomorpha has the least. Anubis baboon (Papio anubis) was the most abundant species (15.14%), followed by Spotted hyena (Crocuta crocuta) (12.98%), Crested porcupine (Hystrix cristata) (12.51%), Vervet monkey (Chlorocebus aethiops) (10.35%), Common duiker (Sylvicapra grimmia) (8.80%), and Giant root-rat (Tachyoryctes macrocephalus) (8.65%). The distributions of mammals among the three habitat types were comparable. The riverine forest harbored the highest mammalian diversity index (H′ = 2.35) followed by the woodland (H′ = 2.32), and the grassland with scattered trees (H′ = 2.30), respectively. The greatest species similarity was recorded in woodland (0.902). The study area harbors considerable mammalian species that are threatened by interacting anthropogenic factors. So, urgent conservation measures by concerned sectors are needed to safeguard these animals and their habitat.

Think Fast!: Vervet Monkeys Assess the Risk of Being Displaced by a Dominant Competitor When Making Foraging Decisions

Foraging animals need to quickly assess the costs and benefits of different foraging decisions, including resource quantity, quality, preference, ease of access, dispersion, distance, and predation risk. Social animals also need to take social context into account and adapt foraging strategies that maximize net resource intake and minimize contest competition with conspecifics. We used an experimental approach to investigate how social context impacts wild vervet monkey (Chlorocebus pygerythrus) foraging decisions in a multi-destination pentagon array. We baited four platforms with less-preferred corn and one platform with a larger, preferred resource (half banana) that required handling time. We ran over 1,000 trials and found that when monkeys foraged alone, they usually took the path that minimized travel distance but prioritized the preferred-food platform when in competition. However, the foraging strategy chosen by low-ranking individuals depended on the handling skill of the decision maker (i.e., time it would take them to retrieve the banana), the relative rank of their audience members (i.e., who has priority-of-access to resources), and the distance audience members were from the experiment site (i.e., their travel time). When the risk of being displaced by a dominant competitor was low (because they were far away and/or because the decision-maker was skilled in retrieving the banana), low-ranking individuals chose a route that minimized travel costs. Conversely, when the risk of losing food to a dominant competitor was high, decision-makers rushed for the preferred-food platform at the onset of the trial. When the risk of displacement was moderate because a dominant audience member was at least 50 m away, low-ranking individuals partly prioritized the preferred-food platform but took the time to stop for one platform of corn on the way. This strategy increased the total amount of food obtained during the trial. These findings suggest that lower-ranking individuals, who experienced high contest competition at the foraging experiment, calculated the risk of being displaced by a dominant competitor when making foraging decisions. This experiment demonstrates that vervets go through a complex decision-making process that simultaneously considers the profitability of different foraging decisions and their social context.

Genetic diversity of Cryptosporidium spp. in non-human primates in rural andurban areas of Ethiopia.

Non-Human Primates (NHPs) harbor Cryptosporidium genotypes that can infect humans and vice versa. NHPs Chlorocebus aethiops and Colobus guereza and humans have overlapping territories in some regions of Ethiopia, which may increase the risk of zoonotic transmission of Cryptosporidium. This cross-sectional study examined the molecular prevalence and subtypes of Cryptosporidium spp. from 185 fecal samples of Chlorocebus aethiops and Colobus guereza in rural and urban areas in Ethiopia. Samples were tested for Cryptosporidium infection using nested polymerase chain reaction (PCR), and subtypes were determined by sequencing a fragment of the 60-kDa glycoprotein gene (gp60). Of the 185 samples, fifty-one (27.56%) tested positive for Cryptosporidium infection. The species detected were C. parvum (n = 34), C. hominis (n = 12), and C. cuniculus (n = 3). Mixed infection with C. parvum and C. hominis were detected in 2 samples. Four C. hominis family subtypes (Ia, Ib, Id, and Ie) and one C. parvum family subtype (IIa) were identified. C. hominis IaA20 (n = 7) and C. parvum IIaA17G1R1 (n = 6) were the most prevalent subtypes detected. These results confirm that Chlorocebus aethiops and Colobus guereza can be infected with diverse C. parvum and C. hominis subtypes that can also potentially infect humans. Additional studies could help to understand the role of NHPs in the zoonotic transmission of Cryptosporidium in Ethiopia.

Drivers and outcomes of between-group conflict in vervet monkeys.

Neighbouring groups compete over access to resources and territories in between-group encounters, which can escalate into between-group conflicts (BGCs). Both the ecological characteristics of a territory and the rival's fighting ability shape the occurrence and outcome of such contests. What remains poorly understood, however, is how seasonal variability in the ecological value of a territory together with fighting ability related to the likelihood of between-group encounters and the extent to which these escalate into conflicts. To test this, we observed and followed four vervet monkey groups in the wild, and recorded the group structure (i.e. size, composition), the locations and the outcomes of 515 BGCs. We then assessed key ecological measures at these locations, such as vegetation availability (estimated from Copernicus Sentinel 2 satellite images) and the intensity of usage of these locations. We tested to what extent these factors together influenced the occurrence and outcomes of BGCs. We found that the occurrence of BGCs increased at locations with higher vegetation availability relative to the annual vegetation availability within the group's home territory. Also, groups engaging in a BGC at locations far away from their home territory were less likely to win a BGC. Regarding group structure, we found that smaller groups systematically won BGCs against larger groups, which can be explained by potentially higher rates of individual free-riding occurring in larger groups. This study sheds light on how the ecology of encounter locations in combination with a group's social characteristics can critically impact the dynamics of BGCs in a non-human primate species.This article is part of the theme issue ‘Intergroup conflict across taxa’.

The effects of fire frequency on vegetation structure and mammal assemblages in a savannah‐woodland system

AbstractFire frequency affects vegetation structure and composition in savannah‐ woodlands, with the potential indirect consequence of affecting the habitat choice and space use of large mammals. Understanding these responses can assist with the development of appropriate fire management policies to conserve co‐existing species with different habitat requirements. In a natural experiment in Majete Wildlife Reserve, Malawi, we compared vegetation composition, woody plant structure and large (&gt;5 kg) mammal assemblages on 10 frequently and 10 infrequently burnt 30‐ha plots, that had fire return intervals of &lt;2.5 and &gt;6 years, respectively, between 2001 and 2019. Fire frequency had little effect on woody plant composition, but did affect grass species composition. Frequent burning reduced mean tree height from 4 to 3 m, woody plant cover from 59% to 35%, and resulted in the dominance of short‐statured, less‐palatable grasses. Many mammal species showed clear preferences for either frequently burnt (e.g. buffalo, zebra, kudu, impala and sable) or infrequently burnt (e.g. nyala, bush pig, baboon, common duiker and vervet monkey) areas, while others (e.g. elephants and black rhinoceros) were not selective. We conclude that establishing a mosaic of patches exposed to different fire frequencies would allow for the persistence of all mammal species in the area by creating an optimal range of habitat types.

Camera traps and guard observations as an alternative to researcher observation for studying anthropogenic foraging.

Foraging by wildlife on anthropogenic foods can have negative impacts on both humans and wildlife. Addressing this issue requires reliable data on the patterns of anthropogenic foraging by wild animals, but while direct observation by researchers can be highly accurate, this method is also costly and labor‐intensive, making it impractical in the long‐term or over large spatial areas. Camera traps and observations by guards employed to deter animals from fields could be efficient alternative methods of data collection for understanding patterns of foraging by wildlife in crop fields. Here, we investigated how data on crop‐foraging by chacma baboons and vervet monkeys collected by camera traps and crop guards predicted data collected by researchers, on a commercial farm in South Africa. We found that data from camera traps and field guard observations predicted crop loss and the frequency of crop‐foraging events from researcher observations for crop‐foraging by baboons and to a lesser extent for vervets. The effectiveness of cameras at capturing crop‐foraging events was dependent on their position on the field edge. We believe that these alternatives to direct observation by researchers represent an efficient and low‐cost method for long‐term and large‐scale monitoring of foraging by wildlife on crops.

MRNA expression analysis of the hippocampus in a vervet monkey model of fetal alcohol spectrum disorder

BackgroundFetal alcohol spectrum disorders (FASD) are common, yet preventable developmental disorders that stem from prenatal exposure to alcohol. This exposure leads to a wide array of behavioural and physical problems with a complex and poorly defined biological basis.Molecular investigations to date predominantly use rodent animal models, but because of genetic, developmental and social behavioral similarity, primate models are more relevant. We previously reported reduced cortical and hippocampal neuron levels in an Old World monkey (Chlorocebus sabaeus) model with ethanol exposure targeted to the period of rapid synaptogenesis and report here an initial molecular study of this model. The goal of this study was to evaluate mRNA expression of the hippocampus at two different behavioural stages (5 months, 2 years) corresponding to human infancy and early childhood.MethodsOffspring of alcohol-preferring or control dams drank a maximum of 3.5 g ethanol per kg body weight or calorically matched sucrose solution 4 days per week during the last 2 months of gestation. Total mRNA expression was measured with the Affymetrix GeneChip Rhesus Macaque Genome Array in a 2 × 2 study design that interrogated two independent variables, age at sacrifice, and alcohol consumption during gestation.Results and discussionStatistical analysis identified a preferential downregulation of expression when interrogating the factor ‘alcohol’ with a balanced effect of upregulation vs. downregulation for the independent variable ‘age’. Functional exploration of both independent variables shows that the alcohol consumption factor generates broad functional annotation clusters that likely implicate a role for epigenetics in the observed differential expression, while the variable age reliably produced functional annotation clusters predominantly related to development. Furthermore, our data reveals a novel connection between EFNB1 and the FASDs; this is highly plausible both due to the role of EFNB1 in neuronal development as well as its central role in craniofrontal nasal syndrome (CFNS). Fold changes for key genes were subsequently confirmed via qRT-PCR.ConclusionPrenatal alcohol exposure leads to global downregulation in mRNA expression. The cellular interference model of EFNB1 provides a potential clue regarding how genetically susceptible individuals may develop the phenotypic triad generally associated with classic fetal alcohol syndrome.