Bonobos (Pan paniscus) inhabit regions south of the Congo River including all areas between its southerly tributaries. To investigate the genetic diversity and evolutionary relationship among bonobo populations, we sequenced mitochondrial DNA from 376 fecal samples collected in seven study populations located within the eastern and western limits of the species’ range. In 136 effective samples from different individuals (range: 7–37 per population), we distinguished 54 haplotypes in six clades (A1, A2, B1, B2, C, D), which included a newly identified clade (D). MtDNA haplotypes were regionally clustered; 83 percent of haplotypes were locality-specific. The distribution of haplotypes across populations and the genetic diversity within populations thus showed highly geographical patterns. Using population distance measures, seven populations were categorized in three clusters: the east, central, and west cohorts. Although further elucidation of historical changes in the geological setting is required, the geographical patterns of genetic diversity seem to be shaped by paleoenvironmental changes during the Pleistocene. The present day riverine barriers appeared to have a weak effect on gene flow among populations, except for the Lomami River, which separates the TL2 population from the others. The central cohort preserves a high genetic diversity, and two unique clades of haplotypes were found in the Wamba/Iyondji populations in the central cohort and in the TL2 population in the eastern cohort respectively. This knowledge may contribute to the planning of bonobo conservation.

The conservation status of western lowland gorillas and central chimpanzees in western equatorial Africa remains largely speculative because many remote areas have never been surveyed and the impact of emergent diseases in the region has not been well documented. In this study, we compared ape densities and habitats in the Lokoué study area in Odzala National Park and the Goualougo Triangle in Nouabalé-Ndoki National Park in northern Republic of Congo. Both of these sites have long been considered strongholds for the conservation of chimpanzees and gorillas, but supposedly differ in vegetative composition and relative ape abundance. We compared habitats between these sites using conventional ground surveys and classified Landsat-7 ETM+ satellite images. We present density estimates via both standing-crop and marked-nest methods for the first time for sympatric apes of the Congo Basin. The marked-nest method was effective in depicting chimpanzee densities, but underestimated gorilla densities at both sites. Marked-nest surveys also revealed a dramatic decline in the ape population of Lokoué which coincided with a local Ebola epidemic. Normal baseline fluctuations in ape nest encounter rates during the repeated passages of marked-nest surveys were clearly distinguishable from a 80% decline in ape nest encounter rates at Lokoué. Our results showed that ape densities, habitat composition, and population dynamics differed between these populations in northern Congo. We emphasize the importance of intensifying monitoring efforts and further refinement of ape survey methods, as our results indicated that even the largest remaining ape populations in intact and protected forests are susceptible to sudden and dramatic declines.

ABSTRACTThe intensification of human activities within the habitats of wild animals is increasing the risk of interspecies disease transmission. This risk is particularly important for great apes, given their close phylogenetic relationship with humans. Areas of high human density or intense research and ecotourism activities expose apes to a high risk of disease spillover from humans. Is this risk lower in areas of low human density? We determined the prevalence ofEscherichia coliantibiotic-resistant isolates in a population of the critically endangered western lowland gorilla (Gorilla gorilla gorilla) and other wild mammals in Lopé National Park (LNP), Gabon, and we tested whether the observed pattern could be explained by bacterial transmission from humans and domestic animals into wildlife populations. Our results show a high prevalence of antibiotic-resistant bacterial isolates in humans and low levels in gorillas and other wildlife. The significant differences in the genetic background of the resistant bacteria isolated from humans and gorillas suggest that transmission is low or does not occur between these two species. These findings indicate that the presence of antibiotic-resistant strains in wildlife do not imply direct bacteria transmission from humans. Thus, in areas of low human density, human-wildlifeE. colitransmission seems to be low. The presence of antibiotic-resistant isolates in gorillas may be better explained by other mechanisms for resistance acquisition, such as horizontal gene exchange among bacteria or naturally acquired resistance.

We examined range use by great apes during logging activities and investigated associations between local variations in ape abundance and changes in the structure of the habitat or in the availability of fruits after disturbances. We carried out two annual censuses of western lowland gorilla (G. g. gorilla) and chimpanzee populations (Pan t. troglodytes) in an active logging concession in Southeast Cameroon. The results suggest that gorillas may adapt their range use to avoid most recently logged compartments, while chimpanzees appear to be more spatially resilient to logging. In our study site, selective logging affected 10% of the forest. After logging, gorillas nested in all types of vegetation, while chimpanzees nested exclusively in mixed mature forest. Fruit availability was not affected by logging and did not explain the distribution of ape nests in the study area.