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Fabrizio Mafessoni: Bonobos' sexual behavior and parental care influence the accumulation of deleterious alleles on the X-chromosome

  • Date: Oct 13, 2016
  • Time: 16:00 - 17:00
  • Speaker: Fabrizio Mafessoni from the MPI for Evolutionary Anthropology in Leipzig
  • For more information on the research group, please check http://www.eva.mpg.de/genetics/genomes/overview.html?Fsize=-1%2527A%253D0
  • Location: MPI Plön
  • Room: Lecture hall
  • Host: Chaitanya Gokhale


Chimpanzees (Pan troglodytes) and bonobos (Pan paniscus) are sister species which differ substantially in behavior. Bonobo societies are described as peaceful and egalitarian: males and females are co-dominant and male competition for mates is moderate, with mothers facilitating their sons’ access to fertile females. In contrast, chimpanzee communities are highly hierarchical and male-dominated, and characterized by intense male competition for mates. These differences in mating behavior can affect their genomic evolution, in particular the evolution of the X chromosome because males carry only one copy of this chromosome while females carry two. We analyzed the exomes of 20 individuals per species and show that the X chromosomes of bonobos, as compared with the autosomes, accumulate a higher proportion of putatively deleterious alleles than those of chimpanzees. This observation is consistent with reduced efficacy of natural selection on bonobo X chromosomes, as we validated with computational simulations implementing directly differences in behavior between the two species.

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