No abstract

One of the most conspicuous behavioural differences among great apes is the paucity of tool use among wild bonobos (Pan paniscus) in comparison to chimpanzees (Pan troglodytes) who are one of the most prolific and skilled tool users in the animal kingdom. This is in spite of the fact that bonobo tool use repertories are as large and diverse as chimpanzees' in captive settings. In this study, we compared tool using behaviours and potential drivers of these behaviours in the Wamba bonobo population located in central Democratic Republic of Congo with the Goualougo chimpanzee population of northern Republic of Congo. The tool use repertoire of wild bonobos was comprised of only 13 behaviours, compared to 42 for chimpanzees. However, the number of tool behaviours observed in each study site was similar between bonobos and chimpanzees, and many types of tool use for social, self-grooming/stimulation, and comfort/protection functions were commonly used by both species. A marked difference is that 25 of 42 tool behaviours exhibited by chimpanzees are performed for feeding, in contrast to a single report of bonobos using a leaf sponge to drink water. We examined whether the differences in tool use repertoires can be explained by the necessity, opportunity, relative profitability, or invention hypotheses. We found that habitat composition and fluctuation of fruit production at these two sites were similar, particularly when compared with variation observed between sites within each species. Thus it was unlikely that the necessity hypothesis explains the lack of tool use for feeding in bonobos. Though further study at Wamba is needed, we did not identify any obvious differences in prey availability that would indicate differences in tool using opportunities between the sites. This study could not test the relative profitability hypothesis, and further research is needed on whether tool use is the most efficient means of calorie or protein intake for wild apes. Bonobos at Wamba formed much larger and stable parties than chimpanzees at Goualougo, which was contrary to the prediction by the invention hypothesis. Another explanation is that differences in tool use behaviour between bonobos and chimpanzees might not be explained by the current ecological or social conditions, but rather by circumstances during the Pleistocene Epoch. The observed species differences might also reflect divergent behavioural predispositions, rather than actual differences in cognitive abilities. One of the most conspicuous behavioural differences among great apes is the paucity of 22 tool use among wild bonobos (Pan paniscus) in comparison to chimpanzees (Pan 23 troglodytes) who are one of the most prolific and skilled tool users in the animal kingdom. 24 This is in spite of the fact that bonobo tool use repertories are as large and diverse as 25 chimpanzees in captive settings. In this study, we compared tool using behaviours and 26 potential drivers of these behaviours in the Wamba bonobo population located in central 27 De...

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.

Objectives: Although conflicts between groups over valuable resources are common in the animal kingdom, an individual's strategy toward out-group individuals may differ according to the benefits and costs received from inter-group interactions. Groups of bonobos encounter each other frequently and may mingle and range together from a few hours to a few days. During these inter-group associations, individuals across groups exhibit both aggressive and affiliative interactions. This study aimed to examine the strategies that bonobos employ with other groups, by comparing the patterns of within-and inter-group aggression. Materials and methods:We observed the aggressive interactions within a group of wild bonobos and between the group and three neighboring groups in Wamba, Luo Scientific Reserve, DR Congo.Results: Bonobos increased the level of cooperation to attack out-group individuals more than they do to attack within-group individuals. Additionally, they reduced the aggression between within-group members during inter-group associations, compared to that when not associated with other groups. Males selectively and cooperatively attacked out-group males. Inter-group aggression among females was rare. Furthermore, females sometimes formed coalitions with out-group individuals to attack a common target. Discussion: Our results support the hypothesis that inter-group competition occurs in bonobos, with males across groups competing over mates. Females across groups were tolerant and even cooperative with each other. Regardless of the ideal male strategy, female tolerant and cooperative relationships across groups and female within-group superiority over males could preserve tolerant inter-group relationships in bonobos. K E Y W O R D S agonistic interactions, cooperation, inter-group relationships, multigroup association, Pan paniscus

No abstract

Although both bonobos and chimpanzees are male-philopatric species, outcomes of male–male reproductive competition seem to be more closely associated with mating success in chimpanzees. This suggests that the extent of male reproductive skew is lower in bonobos. In addition, between-group male–male reproductive competition is more lethal in chimpanzees. This suggests that between-group differentiation in male kinship is lower in bonobos. We analysed the paternity of 17 offspring in two bonobo groups and estimated the relatedness of individuals among three neighbouring groups by using DNA extracted from non-invasive samples at Wamba, in the Democratic Republic of the Congo. The alpha males sired at least nine of 17 offspring. This supports a previous finding that the male reproductive skew is higher in bonobos than that in chimpanzees. Average relatedness among males within groups was significantly higher than that among males across groups, whereas there was no significant difference among females between within and across groups. These results are consistent with male philopatry, highly skewed reproductive success of males and female dispersal. Higher average relatedness among males within groups suggest that the differences in hostility towards males of different groups between bonobos and chimpanzees may be explained by factors other than kinship.

No abstract

No abstract