No abstract

The endangered great ape, Pan paniscus (bonobo) has the smallest range of the African apes. Virtually nothing is known about the genetic diversity or genetic structure of this species, while substantial amounts of polymorphism have been reported for the bonobo's widespread congener, the chimpanzee (P. troglodytes). Given its restricted range, what is the extent of genetic variation in the bonobo relative to the chimpanzee, and is the bonobo genetically depauperate? To investigate patterns of genetic polymorphism, bonobos of wild origin were genotyped for 28 microsatellite loci. The mean number of alleles per locus (5.2) and the mean observed heterozygosity (0.52) in bonobos were similar to variation observed in a wild chimpanzee community (P. t. schweinfurthii). The rarer bonobo is not genetically depauperate and may have genetic diversity comparable to the eastern chimpanzee subspecies. Bonobos have approximately 55% of the allelic diversity and 66% of the observed heterozygosity exhibited by all three chimpanzee subspecies sampled across equatorial Africa. Resampling techniques were used to quantify the effects of sample size differences and number and choice of loci between bonobos and chimpanzees. The examination of these variables underscores their importance in accurately interpreting interspecific comparisons of diversity estimates.

Inbreeding and the loss of genetic diversity may lower fitness and reduce the potential for a population to adapt to changing environments. In small populations, for example in captive populations or populations of endangered species, this can have considerable consequences for their survival. We investigated the effects of inbreeding on infant mortality in the world captive population of bonobos Pan paniscus. Using a combination of studbook data and high-quality pedigree data from genotyped individuals, inbreeding information was available for 142 captive-born individuals. For the determination of paternities that were unresolved in the studbook, nuclear microsatellite DNA was amplified from hair and blood samples using the Great Ape Kit and PowerPlex s 16 System. In total, 54 bonobos (17 offspring and their putative parents) were genotyped at eight tetranucleotide repeat microsatellite loci. Inbreeding coefficients were calculated for each individual for whom paternity was confirmed by either studbook data or DNA analysis. We found significantly higher infant mortality in inbred offspring compared with non-inbred offspring, suggesting that inbreeding reduces infant survival in captive bonobos. In addition, we argue that the total magnitude of inbreeding depression is probably underestimated in this captive population. In conclusion, even though the breeding programme of captive bonobos is aimed at avoiding inbreeding, closely related individuals do occasionally produce offspring that do show inbreeding depression. There is, however, no indication that this currently threatens the long-time survival of the captive population of bonobos.

Among the highest conservation priorities for the bonobo (bilia, Pan paniscus) are to determine the extent of the species' present range, locate major surviving populations, assess habitat and degree of population fragmentation, and quantify the level of threat. Thus, regional surveys are urgently needed (1, 2), as well as quantitation of habitat characteristics. The Action Plan for Pan paniscus (1) identified important potential survey regions. Among these sites is the Salonga National Park (SNP), Democratic Republic of Congo. Designated as a World Heritage Site in 1984, and covering an area over 36,000 km 2 (3), the SNP potentially harbors the largest, relatively undisturbed, and legally protected bonobo habitat. At present it is the only federally protected area for Pan paniscus (1). The park was created in 1970 to protect the bonobo, but early reports indicate that the bonobo's occurrence may be rare to non-existent (3). In order to fully establish a countrywide conservation strategy for the bonobo, it is critical to understand the population status of the bonobo in the SNP, i.e., whether they exist and to what extent the population may be self-sustaining.In