Genetic Structure of Wild Bonobo Populations: Diversity of Mitochondrial DNA and Geographical Distribution

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.

倭黑猩猩（Pan paniscus）栖息于刚果河以南的全部区域，涵盖其南部支流间的所有地域。为探究倭黑猩猩种群间的遗传多样性与演化关系，我们对分布于该物种分布范围东西界限内的7个研究种群的376份粪便样本开展了线粒体DNA测序。在来自不同个体的136份有效样本（各种群样本量范围为7至37份）中，我们在6个进化支（A1、A2、B1、B2、C、D，其中包含一个新鉴定的进化支D）中共区分出54个单倍型。线粒体DNA单倍型呈现区域聚集分布特征，83%的单倍型为种群特有。由此可见，单倍型在种群间的分布模式以及种群内部的遗传多样性均表现出显著的地理格局。通过种群距离测度方法，7个种群被划分为三个集群：东部、中部与西部群簇。尽管尚需进一步阐明地质环境的历史变迁，但遗传多样性的地理格局似乎受更新世时期的古环境变化塑造。现今的河道屏障对种群间的基因流影响较弱，唯有洛马米河（Lomami River）除外——它将TL2种群与其他种群相互分隔。中部集群保留了较高的遗传多样性，且分别在中部集群的万巴/伊永吉（Wamba/Iyondji）种群，以及东部集群的TL2种群中发现了两个独特的单倍型进化支。该研究成果可为倭黑猩猩的保护规划提供科学依据。