Eastern gorilla (Gorilla beringei)

First paragraph: Eastern gorillas (Gorilla beringei Matschie, 1903), occur in the wild more than 1 000 km from the nearest western gorillas (G. gorilla Savage, 1847). They are larger than the western gorilla but otherwise similar, with a broad chest and shoulders, a large head, and a hairless, shiny black face. A full-grown adult male can weigh up to about 220 kg, and a full-grown adult female about half this.46, 97, 99 Two subspecies of eastern gorilla are currently recognized by the Primate Specialist Group of IUCN–The World Conservation Union:48 the eastern lowland or Grauer’s gorilla (G. b. graueri Matschie, 1914); and the mountain gorilla (G. b. beringei Matschie, 1903)

Ape socioecology

First paragraph: This section presents an overview of the socioecology of the seven species of nonhuman apes: bonobos, chimpanzees, gibbons (including siamangs), eastern and western gorillas, and Bornean and Sumatran orangutans. For more detailed information, see Wich et al. (2009b), Emery Thompson and Wrangham (2013), Reinartz, Ingmanson and Vervaecke (2013), Williamson and Butynski (2013a, 2013b), and Williamson, Maisels and Groves (2013)

Impacts of Infrastructure on Apes, Indigenous Peoples and Other Local Communities

Chapter 2 explores the ecological and behavioral impacts of infrastructure on apes in the forest, as well as the social impacts on forest peoples and communities dependent on forest resources. The chapter then offers some lessons learned and steps that can be taken to minimize the deleterious effects of infrastructure development

Gorillas in the crossfire: population dynamics of the Virunga mountain gorillas over the past three decades

Small populations are particularly susceptible to disturbance. Routine censusing to monitor changes is important for understanding both population dynamics and the effectiveness of conservation strategies. Mountain gorillas Gorilla beringei beringei in the Virunga Volcanoes region of Rwanda, Uganda and the Democratic Republic of Congo have been censused five times since 1970. However, due to war and political unrest in the region since 1990, no census had been conducted since 1989, when the population was thought to number 324 gorillas. In 2000 we estimated population size using repeated observations of 17 habituated groups and information on 15 unhabituated groups obtained during patrols. The minimum population was 359 gorillas, and a best-case scenario correcting for groups that might not have been counted was 395. Using the minimum population and best-case scenario respectively, this represents a 0.9% or 1.8% annual growth rate over the last decade and 1.0% or 1.3% annual growth rate since 1972. This is lower than growth estimates made in several population viability analyses, but approximately 5% of the 1989 population is known to have died due to military activity over the last decade. Different subsets of the population exhibited different responses to disturbance caused by war. We discuss conservation strategies that are likely to have contributed to an increase in the gorilla population during this time of turmoil. While the population has grown, the results should be viewed with caution, not only because all known growth during the last decade can be attributed to one subset of the population, but also because the region is still plagued by political unrest

Dominance rank but not body size influences female reproductive success in mountain gorillas

According to life history theory, natural selection has shaped trade-offs for allocating energy among growth, reproduction and maintenance to maximize individual fitness. In social mammals body size and dominance rank are two key variables believed to influence female reproductive success. However, few studies have examined these variables together, particularly in long-lived species. Previous studies found that female dominance rank correlates with reproductive success in mountain gorillas (Gorilla beringei beringei), which is surprising given they have weak dominance relationships and experience seemingly low levels of feeding competition. It is not currently known whether this relationship is primarily driven by a positive correlation between rank and body size. We used the non-invasive parallel laser method to measure two body size variables (back breadth and body length) of 34 wild adult female mountain gorillas, together with long-term dominance and demography data to investigate the interrelationships among body size, dominance rank and two measures of female reproductive success (inter-birth interval N = 29 and infant mortality N = 64). Using linear mixed models, we found no support for body size to be significantly correlated with dominance rank or female reproductive success. Higher-ranking females had significantly shorter inter-birth intervals than lower-ranking ones, but dominance rank was not significantly correlated with infant mortality. Our results suggest that female dominance rank is primarily determined by factors other than linear body dimensions and that high rank provides benefits even in species with weak dominance relationships and abundant year-round food resources. Future studies should focus on the mechanisms behind heterogeneity in female body size in relation to trade-offs in allocating energy to growth, maintenance and lifetime reproductive success

A novel adenovirus of Western lowland gorillas (Gorilla gorilla gorilla)

Adenoviruses (AdV) broadly infect vertebrate hosts including a variety of primates. We identified a novel AdV in the feces of captive gorillas by isolation in cell culture, electron microscopy and PCR. From the supernatants of infected cultures we amplified DNA polymerase (DPOL), preterminal protein (pTP) and hexon gene sequences with generic pan primate AdV PCR assays. The sequences in-between were amplified by long-distance PCRs of 2 - 10 kb length, resulting in a final sequence of 15.6 kb. Phylogenetic analysis placed the novel gorilla AdV into a cluster of primate AdVs belonging to the species Human adenovirus B (HAdV-B). Depending on the analyzed gene, its position within the cluster was variable. To further elucidate its origin, feces samples of wild gorillas were analyzed. AdV hexon sequences were detected which are indicative for three distinct and novel gorilla HAdV-B viruses, among them a virus nearly identical to the novel AdV isolated from captive gorillas. This shows that the discovered virus is a member of a group of HAdV-B viruses that naturally infect gorillas. The mixed phylogenetic clusters of gorilla, chimpanzee, bonobo and human AdVs within the HAdV-B species indicate that host switches may have been a component of the evolution of human and non-human primate HAdV-B viruses

Manual skills for food processing by mountain gorillas in Bwindi Impenetrable National Park, Uganda

Although gorillas rarely use tools in the wild, their manipulative skills during plant processing may be similar to those of other tool-using great apes. Virunga mountain gorillas are known for the complexity in their methods of thistle and nettle plant preparation in the wild. However, there has been no comparable data on food processing in the population of mountain gorillas from the Bwindi Impenetrable National Park, Uganda. We investigated the manual actions and hand grips used when accessing edible parts of two hard-to-process plants defended by stinging hairs, epidermis or periderm (i.e., peel of Urera hypselodendron and pith of Mimulopsis arborescens) and one undefended plant (i.e., leaves of Momordica foetida) in 11 Bwindi wild mountain gorillas (Gorilla beringei beringei) using video records ad libitum. Similar to thistle feeding by Virunga gorillas, Bwindi gorillas used the greatest number of manual actions for the most hard-to-process plant (U. hypselodendron), the actions were ordered in several key stages and organised hierarchically. The demands of processing plant material elicited 19 different grips and variable thumb postures, of which three grips were new and 16 grips have either been previously reported or show clear similarities to grips used by other wild and captive African apes and humans. Moreover, our study only partly supports a functional link between diet and hand morphology in mountain gorillas and suggests that the gorilla hand is best adapted to forceful grasping that is required for both manipulation and arboreal locomotion

The continuous performance test (rCPT) for mice: a novel operant touchscreen test of attentional function.

RATIONALE: Continuous performance tests (CPTs) are widely used to assess attentional processes in a variety of disorders including Alzheimer's disease and schizophrenia. Common human CPTs require discrimination of sequentially presented, visually patterned 'target' and 'non-target' stimuli at a single location. OBJECTIVES: The aims of this study were to evaluate the performance of three popular mouse strains on a novel rodent touchscreen test (rCPT) designed to be analogous to common human CPT variants and to investigate the effects of donepezil, a cholinesterase inhibitor and putative cognitive enhancer. METHODS: C57BL/6J, DBA/2J and CD1 mice (n = 15-16/strain) were trained to baseline performance using four rCPT training stages. Then, probe tests assessed the effects of parameter changes on task performance: stimulus size, duration, contrast, probability, inter-trial interval or inclusion of flanker distractors. rCPT performance was also evaluated following acute administration of donepezil (0-3 mg/kg, i.p.). RESULTS: C57BL/6J and DBA/2J mice showed similar acquisition rates and final baseline performance following rCPT training. On probe tests, rCPT performance of both strains was sensitive to alteration of visual and/or attentional demands (stimulus size, duration, contrast, rate, flanker distraction). Relative to C57BL/6J, DBA/2J mice exhibited (1) decreasing sensitivity (d') across the 45-min session, (2) reduced performance on probes where the appearance of stimuli or adjacent areas were changed (size, contrast, flanking distractors) and (3) larger dose- and stimulus duration-dependent changes in performance following donepezil administration. In contrast, CD1 mice failed to acquire rCPT (stage 3) and pairwise visual discrimination tasks. CONCLUSIONS: rCPT is a potentially useful translational tool for assessing attention in mice and for detecting the effects of nootropic drugs.Funding for this research was provided by Professor Mark Johnson, Imperial College London. CHK received funding from the Korean Health Technology R&D Project, Ministry of Health & Welfare, Republic of Korea (HI11C1183). MHE, SRON, TWR, LMS, TJB and ACM received funding from the Innovative Medicine Initiative Joint Undertaking under grant agreement no 115008 of which resources are composed of EFPIA in-kind contribution and financial contribution from the European Union’s Seventh Framework Programme (FP7/2007-2013). LMS and TJB were funded by Medical Research Council/Wellcome Trust grant 089703/Z/09/Z.This is the final version of the article. It first appeared from Springer via http://dx.doi.org/10.1007/s00213-015-4081-

Dispersal and reproductive careers of male mountain gorillas in Bwindi Impenetrable National Park, Uganda

Dispersal is a key event in the life of an animal and it influences individual reproductive success. Male mountain gorillas exhibit both philopatry and dispersal, resulting in a mixed one-male and multimale social organization. However, little is known about the relationship between male dispersal or philopatry and reproductive careers in Bwindi mountain gorillas. Here we analyze data spanning from 1993 to 2017 on social groups in Bwindi Impenetrable National Park, Uganda to examine the proportion of males that disperse, age of dispersal, pathways to attaining alpha status, fate of dispersing males and philopatric males, and male tenure length as well as make comparisons of these variables to the Virunga mountain gorilla population. We report previously undocumented cases of dispersal by immature males and old males and we also observed the only known case of a fully mature male immigrating into a breeding group. We used genetic tracking of known individuals to estimate that a minimum of 25% of males that disperse to become solitary males eventually form new groups. No differences were found between the Bwindi and Virunga population in the age of male dispersal, the proportion of males that disperse, the age of alpha male acquisition, and dominance tenure length. The lack of differences may be due to small sample sizes or because the observed ecological variability does not lead to life history differences between the populations. Males in both populations follow variable strategies to attain alpha status leading to the variable one-male and multimale social organization, including dispersal to become solitary and eventually form a group, via group fissioning, usurping another alpha male, or inheriting the alpha position when a previous group leader dies

Effects of anterior cingulate cortex lesions on a continuous performance task for mice.

Important tools in the study of prefrontal cortical-dependent executive functions are cross-species behavioural tasks with translational validity. A widely used test of executive function and attention in humans is the continuous performance task (CPT). Optimal performance in variations of this task is associated with activity along the medial wall of the prefrontal cortex, including the anterior cingulate cortex (ACC), for its essential components such as response control, target detection and processing of false alarm errors. We assess the validity of a recently developed rodent touchscreen continuous performance task (rCPT) that is analogous to typical human CPT procedures. Here we evaluate the performance of mice with quinolinic acid-induced lesions centred on the ACC in the rCPT following a range of task parameter manipulations designed to challenge attention and impulse control. Lesioned mice showed a disinhibited response profile expressed as a decreased response criterion and increased false alarm rates. ACC lesions also resulted in a milder increase in inter-trial interval responses ('ITI touches') and hit rate. Lesions did not affect discriminative sensitivity d'. The disinhibited behaviour of ACC lesioned animals was stable and not affected by the manipulation of variable task parameter manipulations designed to increase task difficulty. The results are in general agreement with human studies implicating the ACC in the processing of inappropriate responses. We conclude that the rCPT may be useful for studying prefrontal cortex function in mice and has the capability of providing meaningful links between animal and human cognitive tasks