Primate phageomes are structured by superhost phylogeny and environment.

Humans harbor diverse communities of microorganisms, the majority of which are bacteria in the gastrointestinal tract. These gut bacterial communities in turn host diverse bacteriophage (hereafter phage) communities that have a major impact on their structure, function, and, ultimately, human health. However, the evolutionary and ecological origins of these human-associated phage communities are poorly understood. To address this question, we examined fecal phageomes of 23 wild nonhuman primate taxa, including multiple representatives of all the major primate radiations. We find relatives of the majority of human-associated phages in wild primates. Primate taxa have distinct phageome compositions that exhibit a clear phylosymbiotic signal, and phage-superhost codivergence is often detected for individual phages. Within species, neighboring social groups harbor compositionally and evolutionarily distinct phageomes, which are structured by superhost social behavior. Captive nonhuman primate phageome composition is intermediate between that of their wild counterparts and humans. Phage phylogenies reveal replacement of wild great ape-associated phages with human-associated ones in captivity and, surprisingly, show no signal for the persistence of wild-associated phages in captivity. Together, our results suggest that potentially labile primate-phage associations have persisted across millions of years of evolution. Across primates, these phylosymbiotic and sometimes codiverging phage communities are shaped by transmission between groupmates through grooming and are dramatically modified when primates are moved into captivity.

Discovery of Novel Herpes Simplexviruses in Wild Gorillas, Bonobos, and Chimpanzees Supports Zoonotic Origin of HSV-2.

Viruses closely related to human pathogens can reveal the origins of human infectious diseases. Human herpes simplexvirus type 1 (HSV-1) and type 2 (HSV-2) are hypothesized to have arisen via host-virus codivergence and cross-species transmission. We report the discovery of novel herpes simplexviruses during a large-scale screening of fecal samples from wild gorillas, bonobos, and chimpanzees. Phylogenetic analysis indicates that, contrary to expectation, simplexviruses from these African apes are all more closely related to HSV-2 than to HSV-1. Molecular clock-based hypothesis testing suggests the divergence between HSV-1 and the African great ape simplexviruses likely represents a codivergence event between humans and gorillas. The simplexviruses infecting African great apes subsequently experienced multiple cross-species transmission events over the past 3 My, the most recent of which occurred between humans and bonobos around 1 Ma. These findings revise our understanding of the origins of human herpes simplexviruses and suggest that HSV-2 is one of the earliest zoonotic pathogens.

The complex Y-chromosomal history of gorillas.

Studies of the evolutionary relationships among gorilla populations using autosomal and mitochondrial sequences suggest that male-mediated gene flow may have been important in the past, but data on the Y-chromosomal relationships among the gorilla subspecies are limited. Here, we genotyped blood and noninvasively collected fecal samples from 12 captives and 257 wild male gorillas of known origin representing all four subspecies (Gorilla gorilla gorilla, G. g. diehli, G. beringei beringei, and G. b. graueri) at 10 Y-linked microsatellite loci resulting in 102 unique Y-haplotypes for 224 individuals. We found that western lowland gorilla (G. g. gorilla) haplotypes were consistently more diverse than any other subspecies for all measures of diversity and comprised several genetically distinct groups. However, these did not correspond to geographical proximity and some closely related haplotypes were found several hundred kilometers apart. Similarly, our broad sampling of eastern gorillas revealed that mountain (G. b. beringei) and Grauer's (G. b. graueri) gorilla Y-chromosomal haplotypes did not form distinct clusters. These observations suggest structure in the ancestral population with subsequent mixing of differentiated haplotypes by male dispersal for western lowland gorillas, and postisolation migration or incomplete lineage sorting due to short divergence times for eastern gorillas.

A deepening understanding of animal culture suggests lessons for conservation.

A key goal of conservation is to protect biodiversity by supporting the long-term persistence of viable, natural populations of wild species. Conservation practice has long been guided by genetic, ecological and demographic indicators of risk. Emerging evidence of animal culture across diverse taxa and its role as a driver of evolutionary diversification, population structure and demographic processes may be essential for augmenting these conventional conservation approaches and decision-making. Animal culture was the focus of a ground-breaking resolution under the Convention on the Conservation of Migratory Species of Wild Animals (CMS), an international treaty operating under the UN Environment Programme. Here, we synthesize existing evidence to demonstrate how social learning and animal culture interact with processes important to conservation management. Specifically, we explore how social learning might influence population viability and be an important resource in response to anthropogenic change, and provide examples of how it can result in phenotypically distinct units with different, socially learnt behavioural strategies. While identifying culture and social learning can be challenging, indirect identification and parsimonious inferences may be informative. Finally, we identify relevant methodologies and provide a framework for viewing behavioural data through a cultural lens which might provide new insights for conservation management.

Variability of weaning age in mountain gorillas (Gorilla beringei beringei).

OBJECTIVES: Weaning is a key life history milestone for mammals that represents both the end of nutritional investment from the perspective of mothers and the start of complete nutritional independence for the infants. The age at weaning may vary depending on ecological, social, and demographic factors experienced by the mother and infant. Bwindi mountain gorillas live in different environmental conditions and have longer interbirth intervals than their counterparts in the Virunga Volcanoes, yet other life history characteristics of this population remain less well known. We use long-term data from Bwindi Impenetrable National Park, Uganda to examine factors related to weaning age. MATERIALS AND METHODS: We analyzed data on infants born in four mountain gorilla groups in Bwindi to quantify their age of weaning (defined as last nipple contact) and to test if the sex of offspring, parity, and dominance rank of mother influences age of weaning. We also compared the age at weaning and time to conception after resumption of mating in Bwindi and Virunga gorillas. RESULTS: Bwindi gorillas were weaned at an average age of 57.5 months. No difference was found between age of weaning for primiparous and multiparous mothers, nor did maternal dominance rank influence age of weaning, but sons were weaned at a later age than daughters. The majority of Bwindi mothers were still suckling when they resumed mating and mothers generally conceived before they weaned their previous offspring. The age of weaning was significantly later in Bwindi than in Virunga gorillas. After mothers resumed mating, the time to conceiving the next offspring was not significantly longer for Bwindi females than Virungas females (6 vs. 4 months). DISCUSSION: Later weaning age for sons than daughters is similar to findings of other studies of great apes. Bwindi mountain gorillas are weaned at approximately the same age as western gorillas and chimpanzees, which is more than a year later than Virunga mountain gorillas. The results of this study suggest that variation in ecological conditions of populations living in close geographic proximity can result in variation in life history patterns, which has implications for understanding the evolution of the unique life history patterns of humans.

Assessing attitudes towards gorilla conservation via employee interviews.

To determine the effectiveness of conservation strategies, not only should we monitor biological variables, such as population size and levels of illegal activity, but also we should examine changes in attitudes and behavior of local community members. Here, I use semistructured interviews of employees at two field sites, in Bwindi Impenetrable National Park, Uganda and Loango National Park, Gabon, to understand if their employment influenced their attitude towards gorillas and conservation and led to behavior change. In contrast to western views of gorillas as "gentle giants," staff viewed gorillas as dangerous animals before working for these projects. Overall, employment leads to viewing conservation and gorillas more positively, and in many cases, viewing the gorillas as kin. The most common value attributed to the gorillas was economic, yet intrinsic and non-use existence values were frequently mentioned. Loango staff, but not Bwindi staff, reported behavior change related to hunting and bushmeat consumption, which likely is related to bushmeat consumption being commonplace in Gabon but not in Uganda. The Bwindi staff seemed to have a more positive and broader outlook toward conservation than the Loango staff, possibly because they had more years of formal education, they worked with gorillas longer, there is more history of conservation activities in Bwindi, and/or they have been less directly affected by negative consequences of conservation (e.g., crop raiding). This study shows the importance of explaining that gorillas are not dangerous if not provoked and using their human-like characteristics as a means to change conservation values and interest of local communities, while concurrently recognizing that providing economic benefits and reducing negative effects of wildlife are a reality for conservation buy-in.

An exploration of Menzerath's law in wild mountain gorilla vocal sequences.

Menzerath's law, traditionally framed as a negative relationship between the size of a structure and its constituent parts (e.g. sentences with more clauses have shorter clauses), is widespread across information-coding systems ranging from human language and the vocal and gestural sequences of primates and birds, to the building blocks of DNA, genes and proteins. Here, we analysed an extensive dataset of 'close-call' sequences produced by wild mountain gorillas (Gorilla beringei beringei, no. individuals = 10, no. sequences = 2189) to determine whether, in accordance with Menzerath's law, a negative relationship existed between the number of vocal units in a sequence and the duration of its constituent units. We initially found positive evidence for this but, on closer inspection, the negative relationship was driven entirely by the difference between single- and multi-unit (two to six unit) sequences. Once single-unit sequences were excluded from the analysis, we identified a relationship in the opposite direction, with longer sequences generally composed of longer units. The close-call sequences of mountain gorillas therefore represent an intriguing example of a non-human vocal system that only partially conforms to the predictions of Menzerath's law.

Fruit-feeding and activity patterns of mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park, Uganda.

OBJECTIVES: Availability of fruit is an important factor influencing variation in great ape foraging strategies and activity patterns. This study aims to quantify how frugivory influences activity budgets across age-sex classes of mountain gorillas in Bwindi Impenetrable National Park, Uganda. MATERIALS AND METHODS: Daily proportions of fruit-feeding and activity budgets were calculated using 6 years of observational data on four habituated groups. We fitted generalized linear mixed models to test for age-sex differences in the amount of fruit-feeding, and to test whether these factors influence the proportion of time spent feeding, resting, and traveling. RESULTS: Bwindi mountain gorillas spent on average 15% of feeding time consuming fruit, with monthly variation ranging from 0 to 70%. Greater amounts of fruit-feeding were associated with more time feeding and traveling, and less time resting. Immatures tended to spend more feeding time on fruit than adults, but less overall time feeding and more time traveling. There were no significant differences in the amount of fruit-feeding and overall feeding time between adult females and silverback males, despite differences in body size. DISCUSSION: This study confirms that gorillas are frugivorous, and only the Virunga mountain gorilla population can be characterized as highly folivorous. Along with other frugivorous great apes, Bwindi mountain gorillas alter their activity patterns in response to varying amounts of fruit in their diet. A better understanding of how variable ecological conditions can drive diversity even within a subspecies has important implications for understanding relationships between ecology, body size, and foraging strategies in great apes.

Using long-term ranging patterns to assess within-group and between-group competition in wild mountain gorillas.

BACKGROUND: Competition within and between social groups determines access to resources and can be inferred from space use parameters that reflect depletion of food resources and competitive abilities of groups. Using location data from 1998 to 2017, we investigated within- and between-group competition in 12 groups of wild mountain gorillas (Gorilla beringei beringei). As within-group feeding competition is expected to increase with group size, an increase in group size is predicted to lead to an increase in the size of annual home ranges and core areas, but to a decrease in fidelity (reuse of an area). Due to asymmetries in competitive abilities, larger groups are expected to have higher exclusivity (degree of non-shared space) of annual home ranges and core areas than smaller groups. RESULTS: We found evidence of within-group feeding competition based on a positive relationship between group size and both annual home range and core area size as well as a negative relationship between group size and core area fidelity. Additionally, fidelity of core areas was lower than of home ranges. Between-group competition was inferred from a trend for groups with more members and more males to have more exclusive home ranges and core areas. Lastly, annual core areas were largely mutually exclusive. CONCLUSIONS: Our study suggests that non-territorial, group-living animals can have highly dynamic, long-term avoidance-based spacing patterns, both temporally and spatially, to maintain annual core area exclusivity among groups while concurrently shifting these areas annually within overlapping home ranges to avoid resource depletion. Despite ranging in larger home ranges and core areas, larger groups were able to maintain more exclusive ranges than smaller groups, suggesting a competitive advantage for larger groups in between-group competition in a non-territorial species. Together, these findings contribute to understanding how social animals make behavioral adjustments to mitigate the effects of intraspecific competition.

Ecological correlates of space use patterns in wild western lowland gorillas.

The distribution of resources is a crucial determinant of animals' space use (e.g., daily travel distance, monthly home range size, and revisitation patterns). We examined how variation in ecological parameters affected variability in space use patterns of western lowland gorillas, Gorilla gorilla gorilla. They are an interesting species for investigating this topic because key components of their diet are nonfruit items (herbaceous vegetation and tree leaves) that occur at low density and are sparsely distributed, and fruits, which show high spatiotemporal variation in availability. We estimated how availability of nonfruit foods and fruit, frugivory (proportion of feeding time consuming fruit), and swamps in areas used by the gorillas influenced daily travel distance, monthly home range size, and revisit frequency to grid cells in the home range of one habituated gorilla group in Loango National Park, Gabon. Using location data from 2015 to 2018, we found that the gorillas decreased their daily travel distance as both the density of nonfruit foods and the proportion of swamps in areas used increased. Daily travel distances were shorter when both frugivory and availability of fruit were higher, yet, daily travel distances were longer when availability of fruit was low but frugivory was still high. Furthermore, monthly home range size increased as frugivory increased and monthly revisit frequencies to an area increased as fruit availability of an area increased. In conclusion, the availability of both nonfruit and fruit influenced the gorillas' space use patterns. Gorillas decreased foraging effort when food availability was high but were willing to incur increasing foraging costs to feed on fruit when availability was low. This study highlights how animals have to adjust their space use with changing resource availability and it emphasizes the value of examining multiple parameters of space use.

Unexpected hard-object feeding in Western lowland gorillas.

OBJECTIVES: Gorilla diets are characterized by large amounts of fruit and tough fibrous plant material. Hard-object feeding is not generally associated with this genus as the high crests on their molar teeth would be at risk of damage from the mechanically challenging woody endocarp. This study aims to demonstrate that at least one population of western lowland gorillas are seasonal hard-object feeders, orally processing the seeds of Coula edulis. MATERIALS AND METHODS: Feeding behavior of habituated western lowland gorillas and phenology of fruiting trees was observed over a 4-year period to determine the extent they exploited the seeds of C. edulis. Additionally, the endocarps of C. edulis were subjected to testing to determine their mechanical properties. RESULTS: Our results demonstrate that during the fruiting season (January, February, and December) gorillas consistently opened the seeds of C. edulis using their postcanine dentition. The protective endocarp is composed of a very stiff material, presenting a substantial mechanical challenge to a gorilla. However, the high ratio between elastic modulus and toughness will facilitate brittle, cataclysmic fracture of the seed shell given a high enough load. DISCUSSION: Although a rich energy source, C. edulis likely tax gorilla dentitions to their upper limit. The rarity of such behavior at sites where it could be observed may indicate a degree of social learning or culture driving its occurrence. This shows a greater breadth of gorilla diets than previously described and suggests gorillas may be a useful model for interpreting the dietary mechanics that necessitated robust craniodental morphology in australopiths.

Variation in the social organization of gorillas: Life history and socioecological perspectives.

A focus of socioecological research is to understand how ecological, social, and life history factors influence the variability of social organization within and between species. The genus Gorilla exhibits variability in social organization with western gorilla groups being almost exclusively one-male, yet approximately 40% of mountain gorilla groups are multimale. We review five ultimate causes for the variability in social organization within and among gorilla populations: human disturbance, ecological constraints on group size, risk of infanticide, life history patterns, and population density. We find the most evidence for the ecological constraints and life history hypotheses, but an over-riding explanation remains elusive. The variability may hinge on variation in female dispersal patterns, as females seek a group of optimal size and with a good protector male. Our review illustrates the challenges of understanding why the social organization of closely related species may deviate from predictions based on socioecological and life history theory.

Unexpected terrestrial hand posture diversity in wild mountain gorillas.

OBJECTIVES: Gorillas, along with chimpanzees and bonobos, are ubiquitously described as 'knuckle-walkers.' Consequently, knuckle-walking (KW) has been featured pre-eminently in hypotheses of the pre-bipedal locomotor behavior of hominins and in the evolution of locomotor behavior in apes. However, anecdotal and behavioral accounts suggest that mountain gorillas may utilize a more complex repertoire of hand postures, which could alter current interpretations of African ape locomotion and its role in the emergence of human bipedalism. Here we documented hand postures during terrestrial locomotion in wild mountain gorillas to investigate the frequency with which KW and other hand postures are utilized in the wild. MATERIALS AND METHODS: Multiple high-speed cameras were used to record bouts of terrestrial locomotion of 77 habituated mountain gorillas at Bwindi Impenetrable National Park (Uganda) and Volcanoes National Park (Rwanda). RESULTS: We captured high-speed video of hand contacts in 8% of the world's population of mountain gorillas. Our results reveal that nearly 40% of these gorillas used "non-KW" hand postures, and these hand postures constituted 15% of all hand contacts. Some of these "non-KW" hand postures have never been documented in gorillas, yet match hand postures previously identified in orangutans. DISCUSSION: These results highlight a previously unrecognized level of hand postural diversity in gorillas, and perhaps great apes generally. Although present at lower frequencies than KW, we suggest that the possession of multiple, versatile hand postures present in wild mountain gorillas may represent a shared feature of the African ape and human clade (or even great ape clade) rather than KW per se.

Male-female interactions in multimale groups of mountain gorillas.

Male-female social interactions may vary according to female receptivity, female parity, and male dominance rank. Such variation may be less apparent in species with one-male mating systems than those with multimale mating systems, as within-group male-male competition and female mate choice are absent. Examining variation in male-female interactions in multimale groups in species with a predominantly one-male mating system may help to shed light on plasticity in behavioral patterns and the evolution of mating systems. In this study, we investigated the effect of female receptivity (i.e., days when mating occurred), female parity, and male dominance rank on the patterns of spatial proximity, grooming, following, and aggression among 34 male-female dyads in four multi-male groups of Virunga mountain gorillas. In addition, as a preliminary investigation of potential physiological costs incurred by females in a mating context (coercion), we tested whether female receptivity and female parity explained variation in immunoreactive glucocorticoid (iGC) levels of females. The amount of time male-female dyads spent in close proximity was significantly higher for parous versus nulliparous females and for high- versus low-ranking males. The rate of male aggression to females did not vary significantly with female parity, male rank, or female receptivity. However, post hoc analysis showed that both proximity and aggression increased for the males that participated in the matings on days that females were receptive. Grooming and following by males occurred infrequently. Neither female receptivity nor parity influenced iGC levels in females, a finding that is more consistent with courtship than coercion of females by males. Overall, our results suggest that males advertise their ability to provide protection to females and their offspring, and females seek out males that can do so.

Social and ecological correlates of space use patterns in Bwindi mountain gorillas.

Space use patterns determine access to resources necessary for survival and reproduction. Although it is recognized that the interplay between social and ecological variables shapes spacing patterns, few studies in group-living animals have simultaneously assessed their importance in a comprehensive approach using different spatiotemporal space use measures. In territorial species, such patterns are strongly determined by between-group competition, but its impact in non-territorial species is poorly understood. To better understand the role of social and ecological variables in non-territorial mountain gorillas (Gorilla beringei beringei), we simultaneously evaluated the impact of between-group competition (local gorilla population density and frequency of intergroup encounters) and within-group competition (group size) on space use patterns in 13 gorilla groups in Bwindi Impenetrable National Park, Uganda, while also examining variation in food availability (herbaceous food availability and level of frugivory). We found evidence of between-group competition, indicated by a decline of both monthly home range size and frequency of revisits to each part of the home range as the local gorilla population density increased and by an increase in daily travel distance on days when intergroup encounters occurred. Within-group feeding competition was inferred by a decrease in the frequency of revisits as group size increased. Lastly, food availability influenced the gorillas' spacing patterns, as indicated by a decline in monthly home range size as herbaceous food availability increased and by an increase in daily travel distance as the degree of frugivory increased. In sum, our results suggest that Bwindi gorillas adapted their space use according to the constraints of intraspecific competition and the availability of food resources. We provide some of the first evidence of between-group competition influencing spacing patterns in a non-territorial species. This study suggests a gradient between territoriality and non-territoriality, along which the level of between-group competition varies.

Long-term group membership and dynamics in a wild western lowland gorilla population (Gorilla gorilla gorilla) inferred using non-invasive genetics.

The social organization of a group-living animal is defined by a balance between group dynamic events such as group formation, group dissolution, and dispersal events and group stability in membership and over time. Understanding these processes, which are relevant for questions ranging from disease transmission patterns to the evolution of polygyny, requires long-term monitoring of multiple social units over time. Because all great ape species are long-lived and elusive, the number of studies on these key aspects of social organization are limited, especially for western lowland gorillas (Gorilla gorilla gorilla). In this study, we used non-invasive genetic samples collected within an approximately 100 km2 area of Loango National Park, Gabon to reconstruct group compositions and changes in composition over more than a decade. We identified 98 gorillas and 11 mixed sex groups sampled during 2014-2017. Using published data from 85 individuals and 12 groups surveyed between 2005 and 2009 at the same locality, we tracked groups and individuals back in time. The identification of 11 silverbacks via parentage analyses and the genetic tracking of 39 individuals across studies allowed us to infer six group formations, five group dissolutions, and 40 dispersal events within 12 years. We also observed four groups persisting across the sampling periods with a maximum inferred existence of nearly 17 years and exhibiting variation in membership stability. Our results highlight the variation in composition and stability among groups of western lowland gorillas and illustrate the power of non-invasive genetic sampling for long-term monitoring.

Origin of the HIV-1 group O epidemic in western lowland gorillas.

HIV-1, the cause of AIDS, is composed of four phylogenetic lineages, groups M, N, O, and P, each of which resulted from an independent cross-species transmission event of simian immunodeficiency viruses (SIVs) infecting African apes. Although groups M and N have been traced to geographically distinct chimpanzee communities in southern Cameroon, the reservoirs of groups O and P remain unknown. Here, we screened fecal samples from western lowland (n = 2,611), eastern lowland (n = 103), and mountain (n = 218) gorillas for gorilla SIV (SIVgor) antibodies and nucleic acids. Despite testing wild troops throughout southern Cameroon (n = 14), northern Gabon (n = 16), the Democratic Republic of Congo (n = 2), and Uganda (n = 1), SIVgor was identified at only four sites in southern Cameroon, with prevalences ranging from 0.8-22%. Amplification of partial and full-length SIVgor sequences revealed extensive genetic diversity, but all SIVgor strains were derived from a single lineage within the chimpanzee SIV (SIVcpz) radiation. Two fully sequenced gorilla viruses from southwestern Cameroon were very closely related to, and likely represent the source population of, HIV-1 group P. Most of the genome of a third SIVgor strain, from central Cameroon, was very closely related to HIV-1 group O, again pointing to gorillas as the immediate source. Functional analyses identified the cytidine deaminase APOBEC3G as a barrier for chimpanzee-to-gorilla, but not gorilla-to-human, virus transmission. These data indicate that HIV-1 group O, which spreads epidemically in west central Africa and is estimated to have infected around 100,000 people, originated by cross-species transmission from western lowland gorillas.

Assessing Host-Virus Codivergence for Close Relatives of Merkel Cell Polyomavirus Infecting African Great Apes.

UNLABELLED: It has long been hypothesized that polyomaviruses (PyV; family Polyomaviridae) codiverged with their animal hosts. In contrast, recent analyses suggested that codivergence may only marginally influence the evolution of PyV. We reassess this question by focusing on a single lineage of PyV infecting hominine hosts, the Merkel cell polyomavirus (MCPyV) lineage. By characterizing the genetic diversity of these viruses in seven African great ape taxa, we show that they exhibit very strong host specificity. Reconciliation analyses identify more codivergence than noncodivergence events. In addition, we find that a number of host and PyV divergence events are synchronous. Collectively, our results support codivergence as the dominant process at play during the evolution of the MCPyV lineage. More generally, our results add to the growing body of evidence suggesting an ancient and stable association of PyV and their animal hosts. IMPORTANCE: The processes involved in viral evolution and the interaction of viruses with their hosts are of great scientific interest and public health relevance. It has long been thought that the genetic diversity of double-stranded DNA viruses was generated over long periods of time, similar to typical host evolutionary timescales. This was also hypothesized for polyomaviruses (family Polyomaviridae), a group comprising several human pathogens, but this remains a point of controversy. Here, we investigate this question by focusing on a single lineage of polyomaviruses that infect both humans and their closest relatives, the African great apes. We show that these viruses exhibit considerable host specificity and that their evolution largely mirrors that of their hosts, suggesting that codivergence with their hosts played a major role in their diversification. Our results provide statistical evidence in favor of an association of polyomaviruses and their hosts over millions of years.

Comparison of hand use and forelimb posture during vertical climbing in mountain gorillas (Gorilla beringei beringei) and chimpanzees (Pan troglodytes).

OBJECTIVES: Studies on grasping and limb posture during arboreal locomotion in great apes in their natural environment are scarce and thus, attempts to correlate behavioral and habitat differences with variation in morphology are limited. The aim of this study is to compare hand use and forelimb posture during vertical climbing in wild, habituated mountain gorillas (Gorilla beringei beringei) and semi-free-ranging chimpanzees (Pan troglodytes) to assess differences in the climbing styles that may relate to variation in hand or forelimb morphology and body size. MATERIALS AND METHODS: We investigated hand use and forelimb posture during both ascent and descent vertical climbing in 15 wild mountain gorillas and eight semi-free-ranging chimpanzees, using video records obtained ad libitum. RESULTS: In both apes, forelimb posture was correlated with substrate size during both ascent and descent climbing. While climbing, both apes used power grips and diagonal power grips, including three different thumb postures. Mountain gorillas showed greater ulnar deviation of the wrist during vertical descent than chimpanzees, and the thumb played an important supportive role when gorillas vertically descended lianas. DISCUSSION: We found that both apes generally had the same grip preferences and used similar forelimb postures on supports of a similar size, which is consistent with their overall similarity in hard and soft tissue morphology of the hand and forelimb. However, some species-specific differences in morphology appear to elicit slightly different grasping strategies during vertical climbing between mountain gorillas and chimpanzees.

Evaluating the effect of a year-long film focused environmental education program on Ugandan student knowledge of and attitudes toward great apes.

Films, as part of a larger environmental education program, have the potential to influence the knowledge and attitudes of viewers. However, to date, no evaluations have been published reporting the effectiveness of films, when used within primate range countries as part of a conservation themed program. The Great Ape Education Project was a year-long environmental education program implemented in Uganda for primary school students living adjacent to Kibale National Park (KNP) and Bwindi Impenetrable National Park (BINP). Students viewed a trilogy of conservation films about great apes, produced specifically for this audience, and participated in complementary extra-curricular activities. The knowledge and attitudes of students participating in the program from KNP, but not BINP were assessed using questionnaires prior to (N = 1271) and following (N = 872) the completion of the program. Following the program, students demonstrated a significant increase in their knowledge of threats to great apes and an increase in their knowledge of ways that villagers and students can help conserve great apes. Additionally, student attitudes toward great apes improved following the program. For example, students showed an increase in agreement with liking great apes and viewing them as important to the environment. These data provide evidence that conservation films made specifically to address regional threats and using local actors and settings can positively influence knowledge of and attitudes toward great apes among students living in a primate range country.