Gorilla

Plasmodium falciparum is the most prevalent and lethal of the malaria parasites infecting humans, yet the origin and evolutionary history of this important pathogen remain controversial. Here we develop a single-genome amplification strategy to identify and characterize Plasmodium spp. DNA sequences in faecal samples from wild-living apes. Among nearly 3,000 specimens collected from field sites throughout central Africa, we found Plasmodium infection in chimpanzees (Pan troglodytes) and western gorillas (Gorilla gorilla), but not in eastern gorillas (Gorilla beringei) or bonobos (Pan paniscus). Ape plasmodial infections were highly prevalent, widely distributed and almost always made up of mixed parasite species. Analysis of more than 1,100 mitochondrial, apicoplast and nuclear gene sequences from chimpanzees and gorillas revealed that 99% grouped within one of six host-specific lineages representing distinct Plasmodium species within the subgenus Laverania. One of these from wester...

Western lowland gorillas (Gorilla gorilla gorilla) in zoos are housed in family or bachelor groups to maximize social opportunities. While wild bachelor groups are transient, all male groups in zoos maybe maintained for many years. Captive bachelor groups need  to be carefully monitored, particularly during periods of demographic transition, due to  the possibility for escalating aggression. We examined behavioral changes in a bachelor group at the Saint Louis Zoo following two significant alterations in group composition: (1) the introduction of two immature related males in 2011 and (2) the death of the dominant silverback in 2015. Behavioral data were collected on group members using 15min focal observations with 30-s instantaneous scans, totaling 185.25hr for the first transition and 115.25hr for the second transition (with equal effort in baseline and transition periods). We found that the addition of the two subadult males resulted in a significant increase in affiliation in the group often initiated by these new younger individuals, while the rate of abnormal and aggressive behavior did not change significantly. The rate of abnormal,aggressive, or affiliative behavior in the group also did not change significantly following the death of the dominant silverback. Overall,we conclude that this bachelor group and potentially others can endure possibly destabilizing social transitions and remain cohesive social units. Behavioral changes will result from transitions, but the effect on individuals or impact on the group will vary. Therefore, longitudinal monitoring of bachelor groups will be essential for effective management during any major changes.

Between August and December 1996, there was an outbreak of a debilitating skin disease attributed to Sarcoptes scabiei infection in mountain gorillas (Gorilla beringei beringei) in Bwindi Impenetrable National Park in Uganda. All four members of a gorilla group which had been habituated to tourists were clinically affected; the infant male gorilla was most severely affected and died, the juvenile

SUMMARYAfrican great apes are susceptible to infections with several species of Plasmodium, including the predecessor of Plasmodium falciparum. Little is known about the ecology of these pathogens in gorillas. A total of 131 gorilla fecal samples were collected from Dzanga-Sangha Protected Areas to study the diversity and prevalence of Plasmodium species. The effects of sex and age as factors influencing levels of infection with Plasmodium in habituated gorilla groups were assessed. Ninety-five human blood samples from the same locality were also analysed to test for cross-transmission between humans and gorillas. According to a cytB PCR assay 32% of gorilla's fecal samples and 43·1% human individuals were infected with Plasmodium spp. All Laverania species, Plasmodium vivax, and for the first time Plasmodium ovale were identified from gorilla samples. Plasmodium praefalciparum was present only from habituated individuals and P. falciparum was detected from human samples. Althou...

We tested the effects of age, sex, and season on the nutritional strategies of a group of mountain gorillas (Gorilla beringei) in the Bwindi Impenetrable National Park, Uganda. Through observations of food intake of individual gorillas and nutritional analyses of dietary components over different seasons and environments, we estimated nutrient intake and evaluated diet adequacy. Our results suggest that the nutritional costs of reproduction and growth affect nutrient intake; growing juveniles and adult females ate more food and more protein per kilogram of metabolic body mass than did silverbacks. The diets of silverback males, adult females, and juveniles contained similar concentrations of protein, fiber, and sugar, indicating that adult females and juveniles did not select higher protein foods than silverbacks but rather consumed more dry matter to ingest more protein. Juveniles consumed more minerals (Ca, P, Mg, K, Fe, Zn, Mn, Mo) per kilogram of body mass than adult females and silverback males, and juveniles consumed diets with higher concentrations of phosphorous, iron, and zinc, indicating that the foods they ate contained higher concentrations of these minerals. Seasonally, the amount of food consumed on a dry weight basis did not vary, but with increased frugivory, dietary concentrations of protein and fiber decreased and those of water-soluble carbohydrates increased. Energy intake did not change over the year. With the exception of sodium, gorillas ate diets that exceeded human nutrient requirements. A better understanding of the relative importance of food quantity and quality for different age–sex classes provides insights into the ways in which gorillas may be limited by food resources when faced with environmental heterogeneity.

The classic anthropological hypothesis known as the "obstetrical dilemma" is a well-known explanation for human altriciality, a condition that has significant implications for human social and behavioral evolution. The hypothesis holds that antagonistic selection for a large neonatal brain and a narrow, bipedal-adapted birth canal poses a problem for childbirth; the hominin "solution" is to truncate gestation, resulting in an altricial neonate. This explanation for human altriciality based on pelvic constraints persists despite data linking human life history to that of other species. Here, we present evidence that challenges the importance of pelvic morphology and mechanics in the evolution of human gestation and altriciality. Instead, our analyses suggest that limits to maternal metabolism are the primary constraints on human gestation length and fetal growth. Although pelvic remodeling and encephalization during hominin evolution contributed to the present par...